Keywords: progressive collapse, norms.

Introduction. The purpose of the note is to form a list of existing regulatory materials on the subject of progressive collapse. If possible, a note will be replenished.

Among the documents below are given both those that only make requirements and those that indicate how to count on and what it is necessary to comply with the design requirements.

Subjectively, for the current day the most "saturated" regulatory documents - that kinda (USA): UFC 4-023-03 (Actual 2016)and GSA "Alternate Path Analysis & Design Guidelines For Progressive Collapse Resistance" (2016).They are recommended to get acquainted in the first place. According to the following, except for some domestic recommendations and the Russian-speaking application E TKP 45-3.02-108-2008, are unpleased for practical application and are of interest only in the research plan (look at the evolution of norms, terms, conceptual approaches, calculated techniques).

When comparing the norms / recommendations of the Russian Federation with foreign (US) it is obvious that the first are seriously lagging behind in a meaningful plan. If domestic recommendations containing a lot of contradictions were mainly written in the early mid-23rds and on this process of their update "stalled" *, then the US countries continue to develop gradually. In contrast to our recommendations, which are focused on the basis of J.B. Constructions, US standards contain specific requirements for structures and from other types of materials.- metallic, stone, etc.

Therefore, as it seems, after a certain time (about 5-10 years), we are waiting for the inevitable copy-paste of the individual provisions of Eurocoders and the norms of the United States.

* - issued in 2016-2017. (Project JV "Protection of buildings from progressive collapse ...", SP 296.1325800.2017 "Buildings and structures. Special impacts") with difficulty can be called as follows. Regarding SP 296.1325800.2017 The last statement concerns only its first part on software.

I. RF (in chronological order)

1 . Handbook for the design of residential buildings. Vol. 3. Designs of residential buildings (to SNiP 2.08.01-85). - TsNIIEP housing. - M. - 1986. (see Appendix 2).

Pay attention to the year of this document.- 1986 He refutes the erroneous stereotype, which in the USSR did not do the problem of progressive collapse.

2 . GOST 27751-88 reliability building structures and grounds. Basic provisions for the calculation. - 1988

See paragraph 1.10: "The following settlement situations should be considered when calculating structures:

... emergency, having a small probability of appearance and a small duration, but being very important in terms of the consequences of achieving limit states possible with it (for example, the situation arising in connection with the explosion, collision, equipment accident, fire, and also immediately after denial anydesign element) ... ".

3 . GOST 27.002-89 "Reliability in the technique. Basic concepts. Terms and Definitions". - 1989

This GOST is extremely important in that it is trying to clarify the area of \u200b\u200bdelimitation of the concepts of reliability, survivability, security (see page 20): "... for objects that are a potential source of danger, important concepts are" security "and" vitality ". Safety - property of the object in manufacturing and operation and in case of violation of the RA-Boob State not to make a threat to the life and health of people, as well as for ambient. Although security is not included in the overall concept of reliability, but under certain conditions is closely related to this concept, for example, if refusals can lead to conditions, harmful to people and the environment over maximum permissible norms. The concept of "survivability" occupies a border place between the concepts of "on-duty" and "security". Under the vitality they understand: - the property of the object, co-standing in its ability to withstand the development of critical failures from defects and damage under the installed system of maintenance and repair, orproperty of an object to maintain limited performance when exposeds not provided for in operating conditions, or property of an object to maintain limited performance in the presence of defects or damage to a certain species, as well as in the refusal of some components .

An example is the preservation of the carrying capacity of the structural elements in the occurrence of fatigue cracks, the dimensions of which do not exceed the specified values \u200b\u200b... t ermin "Vitality" corresponds to the international term "Fail-Safe Concept". To characterize fault tolerance in relation to human errors in lately Began to use the term "fool-proof concept".

5 . MGSN 3.01-01 "Residential buildings", - 2001. Paragraphs 3.3, 3.6, 3.24.

6 . NP-031-01 The design standards of seismic-resistant nuclear power plants, - 2001. Note: No settlement techniques are not here, but the principle of a single failure is fixed. It is important.

10 . MHSN 4.19-05 Multifunctional high-rise buildings and complexes. - 2005 Paragraphs 6.25, 14.28, Appendix 6.1.

- If the project is enacted, it will become the first regulatory document in the Russian Federation, containing a dynamic calculation method for a progressive collapse (see paragraph 16 and application "and").

II. . CIS

Ukraine

1.1 .DBN B.1.2-14-2009 General principles ensuring reliability and constructive safety of buildings, structures of building structures and grounds. Paragraph 4.1.6 places the requirements for ensuring the survivability of building structures (the definition is given in clause 3.18).

1.2 . DBN B.2.2-24-2009 Appendix E "Methods for calculating a high-rise building for resistance to progressive collapse" .

Belorussia

2 . TKP 45-3.02-108-2008 (02250) High-rise buildings. It is recommended to pay attention to the Appendix E, "the approaches of foreign standards with the translation into Russian" approaches.

KDIN \u003d 2 (see paragraph E.3.1.2.6).

7 . EN 1992-1-1-2009 Eurocode 2: Design of Concrete Structures - Part 1-1.

Great Britain

8 . BS 5950-1: 2000 (Edition 2008: Incorporating Corrigenda NOS. 1 And 2 And Amendment No. 1) Structural Use Of Steelwork in Building. See section 2.4.5 STRUCTURAL INTEGRITY.

9 . BS 8110-1: 1997 (Edition 2007: Incorporating Amendments NOS. 1, 2, 3 AND 4) STRUCTURAL USE OF CONCRETE. See Section 2.2.2.2 Robustness. The document refers to paragraph 2.6 BS 8110-2: 1985.

10 . BS 8110-2: 1985 (Edition 2005: REPRINTED, Incorporation Amendments NOS. 1, 2 and 3) Structural Use of Concrete. Part 2: Code of Practice for Special Circumstances. See section 2.6 Robustness.

11 . BS 5628-1: 2005 Code of Practice for Use of Masonry (Edition 2005). See Sections 5 Design: Accidental Damage.

Canada

12. NBCC 1977 National Building Code of Canada (NBCC), Part 4, Commentary C, National Research Council Of Canada, Ottawa, Ontario, 1985.

13. CSA STANDARD S16-01 LIMIT STATES DESIGN OF STEEL STRUCTURES. See clause 6.1.2 Structural Integrity.

Hong Kong.

14. Code of Practice for Structural Use of Concrete, - 2013. See paragraph 2.2.3.2 Check of Structural Integrity, p. 2.3.2.7 Fire, Section 6.4 Design for Robustness Against Disproportionate Collapse.

15. Code of Practice for Structural Use Of Steel, - 2011.

See paragraph 1.2.1, 1.2.3 Structural System, Integrity and Robustness, p. 2.3.4 STRUCTURAL INTEGRITY AND ROBUSTNESS, Clause 2.3.4.3 Avoidance of Disproportionate Collapse, p. 12.1.1, 12.1.3, 13.1. 4.1 Robustness.

16. Code of Practice for Dead and Imposed Loads, - 2011.

Australian / New Zealand

17 . AS / NZS 1170.0: 2002 STRUCTURAL DESIGN ACTIONS. Part 0: General Principles (Edition 2011). See Section 3.2 Design Requirements, Section 6 Structural Robustness.

1 . Tour V.V. Assessment of risks of constructive systems in special settlement situations. Herald of Polotsk State. Unison Series F, p. 2-14, - 2009.

2.1 . Grachev V.Yu., Vershinina T.A., Puzatkin A.A. Disproportionate destruction. Comparison of calculation methods. Yekaterinburg, Publishing House "Azhur", - 2010, 81 p.

2.2 . Grachev V.Yu. and partners. Selective translation "Progressive Collapse Analysis and Design Guidelines for New Federal Office Buildings and Major Modernization Projects". GSA. ( Approx.: translation already irrelevant version from 2003.; transfer in places not "The Best", but in general the work is done big).

3 . Eremeev P.G. Prevent avalanche-like (progressive) collapse of the supporting structures of unique Bolshevoltro-Troytric buildings in emergency effects. Construction mechanics and calculation of structures, - 2006, No. 02.

4 . Review of International Research on Structural Robustness and Disproportionate Collapse. London, Department for Communication and Local Government, - 2011.

5 . A. Way SCI P391 Structural Robustness of Steel Framed Buildings. - 2011. UK.

6 . Brooker O. How to Design Concrete Buildings to Satisfy Disproportionate Collapse Requirements.

Preface

1. Developed: MNIITEP (engineers Shapiro G.I. - Head of work, Eisman Yu.A.) and Raasn (Academician, Doctor of Technical Sciences, V.I.).

2. Prepared for the publication of the GUP MNIITEP.

3. Agreed: TsNIIK them. Kucherenko, TsNIIEP housing.

4. Approved and entered into force the disposal of the management of scientific and technical policy, the development and reconstruction of the city of Moscow dated 16.02.2006 N 9.

Introduction

Recommendations are intended for the design and construction of new, as well as reconstructions and inspections of the built high-altitude (multifunctional, administrative, residential) buildings, or high-altitude parts of a different-storey building, any constructive systems with a height of more than 25 floors (75 m) for stability against progressive collapse when local damage occurs. .

The need to develop these recommendations arose due to the fact that the available documents do not cover issues related to design and verification high-rise buildings. High-rise houses have a number of features associated with more "free" architectural and planning solutions, a wide step of walls (or columns), solutions of carrier and enclosing structures, etc., which causes the specifics of the calculation of high-rise buildings for stability against progressive collapse in emergency situations. (Emergency).

The main purpose of this technique is to ensure the safety of high-rise buildings during projects for projects.

Emergency situations (emergencies) caused by project sources are generally unpredictable and reduced to local emergency effects on separate designs of a single building: explosions, fires, karst dips, accidents, defects of structures and materials, incompetent reconstruction (redevelopment), etc. Cases.

As a rule, the impact of the type under consideration leads to local damage to the supporting structures of buildings. At the same time, in some cases, these initial damage and are exhausted, and in others, the supporting structures, which remained at the first moment of the accident, do not withstand the additional load, previously perceived damaged elements, are also destroyed. The last type of accidents received the name "progressive collapse" in the literature.

1 Main provisions

1.1 High-rise buildings should be protected from the progressive (chain) collapse in the event of local destruction of their supporting structures in emergency influences not provided for by the conditions of normal operation of buildings (fires, explosions, drumming effects of vehicles, unauthorized redevelopment, etc.). This requirement means that in the event of emergency exposures, local destruction of individual vertical bearing elements within one floor or part of overlapping one floor are allowed, but these initial destruction should not lead to the collapse or destruction of structures to which the load has been transmitted, previously perceived by elements damaged by the emergency exposure.

The calculation of the building in the case of local destruction of the supporting structures is made only by the limit states of the first group. The development of inelastic deformations, the movement of structures and the disclosure of cracks in them in the emergency in question are not limited.

1.2 Stability of a high-rise building against progressive collapse should be ensured by the most cost-effective means:

- a rational constructive-planning solution of the building, taking into account the possibility of the emergence of the emergency situation under consideration;

- constructive measures that ensure confusing structures;

- application of materials and constructive decisionsensuring development in elements of structures and their compounds of plastic deformations.

1.3 Reconstruction of a high-rise building, in particular redevelopment and reorganization of premises, should not reduce its stability against progressive collapse.

1.4 As a local (hypothetical) destruction, the destruction should be considered (removal) of vertical structures of one (any) floor of a building bounded by a circular area of \u200b\u200bup to 80 m (diameter 10 m) for buildings with a height of up to 200 m and up to 100 m (diameter 11.5 m ) for buildings above 200 m:

a) two intersecting walls in areas from the location of their intersection (in particular, from the corner of the building) to the nearest opening in each wall or until the next vertical joint with a wall of another direction or the section of the specified size;

b) columns (pylons) or columns (pylons) with sections of walls adjacent to them, including hinged enclosing panels located on a plot that does not exceed the specified size of local destruction;

c) overlap on the specified area.

To assess the stability of the building against progressive collapse, only the most dangerous calculation schemes of destruction are allowed. It is necessary to test the protected from the progressive collapse of the designs of all typical, technical and underground floors, as well as the attic.

2 Drawing loads and resistance of materials

2.1 Calculation of strength and stability is made on a special combination of loads and impacts, including constant and long time loads, as well as the impact on the construction of the building of local hypothetical destruction of claim 14.4. Local destruction can be located anywhere building.

2.2 Permanent and long-term temporary loads are accepted according to current regulatory documents (or on a special task) with coefficients of combination of loads and reliability coefficients for loads equal to one.

2.3 Estimated strength and deformation characteristics of materials are taken equal to their regulatory values \u200b\u200baccording to the current standoff standards of reinforced concrete and steel structures.

3 Calculation of high-rise buildings for stability against progressive collapse

3.1 To calculate high-altitude buildings, it is recommended to use a spatial calculation model. In the model, elements may be taken into account, which under normal operating conditions are nonsense (for example, mounted outer wall panels, reinforced concrete fencing of balconies, etc.), and if local influences are actively involved in the redistribution of efforts in the elements of the structural system.

The design model of the building should provide for the possibility of removal (destruction) of individual vertical structural elements in accordance with clause 1.4.

The removal of one or several elements changes the structural scheme and the nature of the work of the elements adjacent to the destroyer or dependent on it, which must be considered when prescribing the rapid characteristics of the elements and their connections.

The design model of the building should be calculated separately, taking into account each (one) of local destruction.

3.2 Building Calculation can be performed using various software complexes, including based on the finite element method. The use of software complexes that allow the possibility of taking into account the physical and geometric nonlinearity of the rapid characteristics of the elements provides the greatest reliability of the calculation results and a decrease in additional material costosity.

The efforts obtained on the basis of the static calculation in separate structural elements should be compared with the limit efforts that can be perceived by these elements. The stability of the building against the progressive collapse is provided if a condition is observed for any element, where and, accordingly, force in the structural element found from the static calculation made, and its calculated bearing ability, found taking into account the indications of clause 2.3. Designs for which the strength requirements are not satisfied should be strengthened, or other measures should be taken that increase the structures resistance to progressive collapse.

3.3 When determining the limit efforts in elements (their bearing capacity), it should be taken:

a) a long-acting part of the effort - on the calculation of the structural circuit with the calculated scheme without local destruction on the loads indicated in paragraph 2.2;

b) briefly active part of the effort - as a difference of efforts obtained from the calculation of the structural circuit in the calculated scheme, taking into account the removal (destruction) of one of the carrier elements (see clause 1.4) on the action of the same loads and efforts obtained from the calculation of .but).

3.4 In the case of ensuring the plastic operation of the constructive system in the limit state, checking the stability against the progressive collapse of the elements located above local destruction is recommended to be carried out by the kinematic method of the limit equilibrium theory that gives the most economical solution. In this case, the calculation of the building with each selected scheme is performed according to the following procedure:

- the most likely mechanisms of the progressive (secondary) collapse of the elements of the building that have lost their support are set (set the mechanism of destruction means to determine all the ruined links, including the formed plastic hinges, and find possible generalized movements () in the direction of efforts in these links);

- For each of the selected progressive collaboration mechanisms, limit efforts are determined, which can be perceived by the sections of all plastic destroyable elements and connections (), including plastic hinges; There are equal () external forces applied to a separate links of the mechanism, that is, to individual non-destructive elements or their parts, and moving in the direction of their action ();

- the works of the internal forces () and external loads () are determined on the possible movements of the mechanism under consideration.

and the condition of equilibrium is checked

In assessing the possibility of simultaneous collapse of the structures of all floors, the equilibrium conditions (1) is replaced by the condition

Where and is, accordingly, the work of internal and external forces on the movements of the designs of one floor; Floors are separated by the lower surface of the overlap, which refers to the floor located above the overlap.

This calculated procedure is applicable only subject to the requirements of claim 4.2, 4.3 on ensuring the plastic work of individual structural elements and links between them in the limit state. If the plasticity of any element or communication is not provided, their work should not be taken into account (the element or relationship is considered absent). If such elements and connections that can be destroyed by the fragile, too much, and their formal exclusion reduces the assessment of the building resistance to the progressive collapse, should or ensure the plasticity of the relationship, or use another design model of the building (see clause 3.2).

With each selected local destruction, it is necessary to consider all the following mechanisms for the progressive collapse:

- The first mechanism of progressive collapse is characterized by simultaneous translational displacement of all vertical structures (or individual parts) located above local destruction.

- The mechanism of the progressive collapse of the second type is characterized by simultaneously turning each structural part of the building located above the local destruction, around its center of rotation. Such a displacement requires the destruction of the existing connections of these structures with intact building elements; Destruction of shifting of vertical elements with overlapping.

- The third collapse mechanism is the condition of the unbreak of only the overlap section, located directly above the knocked vertical design and is initially opened on it.

- The fourth mechanism provides for the movement of structures of only one floor, located directly above the knocked vertical element. In this case, there is a separation of vertical structures from the overlap located above them.

If, with any calculated scheme, condition (1) or (2) is not performed, it is necessary to achieve its execution with the strengthening of structural elements or other events.

3.5 In some cases, it is advisable to consider the work of overlaps over the remote column (pylon, wall) at large deflections as elements of the suspended system or taking into account the membrane effect.

3.6 In the bearing columns (pilons, walls), not located above hypothetical destruction, its impact leads to an increase in stresses and effort. You must verify the strength of these elements. An assessment of the efforts acting in the elements is allowed to be carried out by approximate methods.

3.7 Each overlap of a high-rise building must be calculated on the perception of the weight of the overlap section of the overlay floor (constant and long load with the coefficient of dynamism \u003d 1.5) on an area of \u200b\u200b80 m for buildings up to 200 m and 100 m for buildings above 200 m.

4 Constructive requirements

4.1 The main means of protecting high-rise buildings from the progressive collapse - ensuring the necessary strength of the structural elements in accordance with the calculations; an increase in the plastic properties of the applied fittings and steel bonds between the structures (in the form of fittings of the connected structures, mortgage parts, etc.); The inclusion in the work of the spatial system of non-oscillating elements. The effective operation of connections that prevent progressive collapse is possible only when providing their plasticity in the limit state so that they do not turn off from work and allowed the development of the necessary deformations without destruction. To fulfill this, the communication requirement should be designed from plastic sheet or reinforcement steel, and the strength of the anchoring of links should be more efforts that cause their fluidity.

4.2 The buildings should be given preference to monolithic and collecting-monolithic overlaps, which must be reliably connected to the vertical supporting structures of the building with steel connections.

4.3 Compounds of prefabricated elements with monolithic structures that prevent the progressive collapse of buildings should be designed to be inequalized, while the element, the limit state of which ensures the largest plastic deformations of the compound, should be the least strong.

To perform this condition, it is recommended to calculate all the elements of the compound, except for the most plastic, for an effort, 1.5 times higher than the bearing capacity of the plastic element, for example, an anchoring of mortgage parts and welded joints is recommended to calculate for an effort 1.5 times more than the bearing capacity Communication itself. It is necessary to especially follow the actual execution of the design solutions of plastic elements, the replacement of their more durable is unacceptable.

4.4 To increase the efficiency of resistance to the progressive collapse of the building, it is recommended:

- Supported jumpers working as shift links, design so that they are destroyed from bending, and not on the action of transverse force;

- key connections in collecting-monolithic structures to design so that the strength of the individual knaps on the slice was 1.5 times more of their strength at the crumination;

- ensure the adequacy of the length of the anchoring of reinforcement when it works as a shift connection;

- Supporting sections of beams and riggers, as well as the nodes of their compounds with columns (walls, pylons), must have a transverse strength of 1.5 times higher than their bending ability to be taking into account plastic properties in the spangle.

4.5 The minimum cross-sectional area (total for the lower and upper reinforcement) of horizontal fittings, both longitudinal and transverse in reinforced concrete floors and the coating should be at least 0.25% of the concrete cross section.

At the same time, the specified fittings should be continuous and shake in accordance with the requirements of existing regulatory documents on the design of reinforced concrete structures.

4.6 Horizontal connections of concrete or reinforced concrete mounted outer panels with supporting elements of the building should perceive stretching forces of at least: 10 kN (1 TC) per 1 m panel lengths at the height of the floor 3.0 m; 12 KP per 1 m panel lengths at the height of the floor is 3.5 m; 14 kN per 1 m panel lengths at the height of the floor is 4.0 m and higher, if it is not required for the calculation.

4.7 Longitudinal (vertical) Bison fittings Pilon (columns, walls) should perceive stretching forces of at least 10 kN (1 TC) for each square meter of cargo area of \u200b\u200bthis pylon (columns, walls).

4.8 In buildings with the use of metal structures, it includes stolerele-concrete floors, avoid flexible bolt connections with columns. Horizontal wind bonds should ensure the union of the overlap disk. Use steel with high plasticity and viscosity.

Appendix A. Examples of calculation

Appendix A.

This application discussed two calculation examples *:
_______________
* Student MGSU Yuriev R.V. took part in the calculation of examples.

- In the first example A1, resistance was considered against progressive collapse for several schemes for local destruction of the carrying structures of one section of a residential thirty-five-story house with a height of 123.2 m. The calculation of the ceiling was carried out using the kinematic method of limiting equilibrium, and vertical structures - using the software complex "Monomakh 4.0" .

- In the second example, A2 examined the stability against the progressive collapse of the multifunctional 74-storey house of a similar tower of Moscow-City, a height of 266.4 m. Calculation of structures for certain schemes of local destruction was carried out using the LIRA 9.2 and SNIP installation complexes - progressive collapse.

For both examples, the results of calculations of certain schemes of local destruction are given.

A1 Example of calculating the thirty-fictional monolithic residential building
On stability against progressive collapse

A1.1 Initial data

A1.1.1 Description of the Constructive System

The supporting structures of the building are made in monolithic reinforced concrete. Plan typical floor The buildings are presented in Figure A1. Constructive building mixed building. The ladder-lift node forms the core of rigidity. The thickness of the bearing inner walls 35 cm, the thickness of the pylons is 40-50 cm, the length of pylons up to 200 cm. Overlapping and coating - monolithic, 22 cm thick, protective layer of concrete 2.5 cm. All vertical building structures are made of heavy concrete grade On compression B45, overlap from concrete class B25. The background reinforcement of overlapping is continuous symmetrical same along both directions of the axes of the building: the upper fittings are equal to the lower and amounts to 12a400 with a cell of 30 cm. The height of the floor \u003d 3.52 m. The outer walls are mounted from non-delicate small-piece materials.

Figure A1.1 Plan of the standard floor of a monolithic high-rise residential building

A1.1.2 Load

Regulatory uniformly distributed loads at the overlap: own weight 5.5 kN / m; floor weight in apartments 2 kN / m; Paul weight on a balcony of 1.2 kN / m; Weight of partitions inside apartments 1.1 kN / m; Long temporary load from people in apartments and on balconies 0.3 kN / m. Full uniformly distributed load: in apartments 8.9 kN / m; On the balconies of 7 kN / m. The weight of the outer walls is 11.1 kN / b. Fencing balconies 3.5 kN / m.

A1.1.3 Calculated Material Resistance

The letter denotes the values \u200b\u200bnot specified in the present calculation were adopted by SNIP 2.03.02-84 *, SNIP 52-01-2003 and SP 52-101-03 [,,].
_______________
Specifies before the entry into force of the relevant technical regulation.

It is recommended to register the Ministry of Justice of Russia.

Probably the error of the original. Snip 2.03.02-86 should be read. - Note database manufacturer.

Concrete class for compressive strength B25: 18.5 MPa;
1.55 MPa.

Concrete class for compressive strength B45: 32 MPa;
2.2 MPa.

Armature 12A400: resistance to stretching 400 MPa;
Sing 400 * 0.8 \u003d 320 MPa.

The carriers of the elements are determined according to the requirements of the joint venture 52-101-03 using the "SNiP reinforced concrete" program.

A1.1.4 Calculation schemes of hypothetical local destruction

The options for the arrangement of the hypothetical local destruction of the standard floor, discussed in the present example, are shown in Figure A1.

In the height of the building, local destruction can be located on any floor, so if there are several types of sample floors in the building, then you need to check the most dangerous (or all). In addition, it is necessary to check the impossibility of the progressive collapse of the articles of the attic, technical and underground floors. Here, as an example, the three most dangerous schemes of the local destruction of the standard-floor designs corresponding to the requirement of claim 4.5, including three possible options The formation of plastic hinges for the scheme 1.

A1.2 Calculation of structures located above local destruction, kinematic method of limit equilibrium theory

A1.2.1 Beneficial ability of individual structural elements

A1.2.1.1 Overlap

The routing bending ability of cross-sections with background reinforcement of bending when stretching the lower (or upper) fibers during bending along the directions of the letter and digital axes are the same, is determined by \u003d 100 cm; \u003d 19.5 cm; \u003d 3.77 cm (3.3 rod diameter 12 mm made of steel class A400); \u003d 400 MPa, concrete class B25, \u003d 18.5 MPa and is equal to 28 kN · m / m / m. Armature area is: \u003d 3.77 * 2 / (22 * 100) * 100% \u003d 0.34%\u003e 0.25%, i.e. More minimal reinforcement according to claim 4.5 of these recommendations.

A1.2.2 Checking the stability of the building with the local destruction of its supporting structures according to scheme N 1

Figure A1.2 Scheme 1. The wedding mechanism of the first type

The collapse of the structural cell is considered between the A - B and 1-3 axes. The pylon-thief in the intersection of axes 1 and B. is primarily destroyed at the intersection of axes 1 and B. It is checked the inability to collapse over the local destruction of sections of floors and pylons. Since the pylon with other vertical structures is connected only through the overlap, the progressive collapse in this case resists on each floor only the overlap, which is destroyed with the formation of plastic hinges, and the shoulder bog with a pylon.

A1.2.2.1 Assessing the possibility of the mechanism of the progressive collapse of the first type

The hypothetical scheme of progressive collapse is presented in Figure A1.2. Pylons of all the floors hanging on the "destroyed" pylon on the floor are progressively shifted down together with the adjacent floors of the floors, plastic hinges with stretching of the upper (in the figures are indicated by a solid line) and the lower (dotted line) of reinforcement) in the overlaps.

Pilon work

The pylon (cross section 40x200 cm) is progressively shifted down without destruction, the operation of the internal forces \u003d 0. Pilon weight \u003d 25 * 0.4 * 2 * 3,3 \u003d 66 kN; Vertical movement \u003d 1; Work of external forces \u003d 66 * 1 \u003d 66 kN.

Resistance to the collapse of overlaps

The operation of the inner forces of the overlap is summed according to all shown in Figure A1.2 and numbered numbers in the circles of plastic hinges (\u003d 1, ... 8). For each plastic hinge, where - the bending moment, perceived by the cross section of the overlap along the plastic hinge under consideration; - Corner of the slab of the plate, - the length of the plastic hinge. For hinges, inclined to the direction of the axes of the building, where the sharp corner between the direction of the hinge and the direction of the digital axis.

In order to standardize the calculation of the corners of the overlap in plastic hinges, formed by two inclined planes, were considered as the sum of two angles (each inclined plane with horizontal), such as hinges 7 and 8. Then, where - the length of the perpendicular to the lines of the plastic hinge connecting 2 The points of the plane under consideration, the difference between the movements of which is equal to one.

Hinge 1: \u003d 28 * 2.2 \u003d 60.6 kNm; \u003d 1 / 4,4 \u003d 0.22 m; \u003d 60.6 * 0.22 \u003d 13 kN;

Hinge 2: \u003d 28 * 2.2 \u003d 60.6 kNm; \u003d 1 / 4.3 \u003d 0.233 m; \u003d 60.6 * 0.233 \u003d 14 kN;

Hinge 3: \u003d 28 * (COs3 + sin3 °) * 6.7 \u003d 187 kNm; \u003d 1 / 4.3 \u003d 0.233 m; \u003d 187 * 0.233 \u003d 44 kN;

Shrap 4: \u003d 28 * (COS14 ° + SIN14 °) * 15,4 \u003d 431 kNm; \u003d 1 / 4.2 \u003d 0.24 m; \u003d 431 * 0.24 \u003d 104 kN;

Shupnip 5: \u003d 28 * (COS35 ° + SIN35 °) * 9.7 \u003d 272 kNm; \u003d 1 / 5.7 \u003d 0.175 m; \u003d 272 * 0.175 \u003d 48 kN;

Hinge 6: \u003d 28 * (COS45 ° + SIN45 °) * 5.8 \u003d 162 kNm; \u003d 1 / 6.3 \u003d 0.16 m; \u003d 162 * 0.16 \u003d 26 kN;

Hinge 7: \u003d 28 * (COS7 ° + sin7 °) * 12 \u003d 336 kNm; \u003d 1 / 4.5 \u003d 0.222 m; \u003d 336 * 0.222 \u003d 75 kN;

Hinge 8: \u003d 336 kNm; \u003d 1 / 6.5 \u003d 0.154 m; \u003d 336 * 0.154 \u003d 52 kN;

Total overlaid \u003d 13 + 14 + 44 + 104 + 48 + 26 + 75 + 52 \u003d 374 kN.

Work external forces on overlap movements

(\u003d 1, 2, 3). , where - distributed external loads; - the area of \u200b\u200bthe collapsed part of the ceiling slab, to which these loads are applied; - Moving the center of gravity of the plate. The values \u200b\u200band are indicated in Figure A1.2. Work of external forces

\u003d 8.9 * (38 * 0.381 + 14.4 * 0.325 + 27.6 * 0.333) \u003d 255 kN.

Exterior walls (Conditionally in Figure A1.2 shows only on the plans)

The operation of the internal forces \u003d 0.

The work of external forces on the movements of the outer walls (\u003d 1, 2). , where - distributed by length external loads from the weight of the outer walls or the fencing of balconies; - the length of the outer wall; - Vertical movement of the center of severity of the outer wall.

\u003d 11.1 * (5.6 * 0.5 + 4.7 * 0.5) \u003d 57 kN.

Checking the general condition of the impossibility of education of the mechanism of the first type

Verification is made according to the formula (2) of these recommendations

377 kN;

66 + 255 + 57 \u003d 378 kN377 kN.

The stability condition of the structures is made. The progressive collapse of the first type is impossible.

A1.2.2.2 Assessing the possibility of the mechanism of the progressive collapse of the second type

The hypothetical scheme of the progressive collapse is presented in Figure A1.3. Plastic hinges with stretching of the upper and lower fittings are formed in the ceiling. The pylons of all the floors hanging on the "disappeared" pylon on-floor are rotated together with the lower overlap around the instantaneous center of rotation at the intersection of the axes B and 3, the pylon shake with the upper overlap is destroyed by the cut.

Figure A1.3 Scheme 1. Second type collapse mechanism

Pilon work

Pilon weight \u003d 66 kN; Moving under the center of gravity of the pylon \u003d 13/14 \u003d 0.93; Work of external forces \u003d 66 * 0.93 \u003d 61 kN.

Resistance to the collapse of the overlap

The operation of the internal overlap forces is summed according to all shown in Figure A1.3 and numbered films plastic hinges (\u003d 1, ... 4).

For each plastic hinge, where - the bending moment, perceived by the cross section of the overlap along the plastic hinge under consideration; - Corner of the slaughter of the plate.

The work of the domestic forces on the movements of plastic hinges:

Hinge 1: \u003d 28 * (COS24 ° + SIN24 °) * 16.3 \u003d 456 kNm; \u003d 1 / 4.3 \u003d 0.233 m; \u003d 456 * 0.233 \u003d 106 kN;

Hinge 2: \u003d 28 * (COS14 ° + SIN14 °) * 15.5 \u003d 434 kNm; \u003d 1 / 4.7 \u003d 0.213 m; \u003d 434 * 0,213 \u003d 92 kN;

Hinge 3: \u003d 28 * (COS6 ° + sin6 °) * 14,2 \u003d 398 kNm; \u003d 1 / 4.5 \u003d 0.222 m; \u003d 398 * 0,222 \u003d 88 kN;

Hinge 4: \u003d 398 kNm; \u003d 1/5 \u003d 0.2 m; \u003d 398 * 0.2 \u003d 80 kN

Total overlaid: \u003d 106 + 92 + 88 + 80 \u003d 366 kN.

Work external forces on overlap movements (see Figure A1.3)

\u003d 8.9 * (38 * 0.34 + 29 * 0.28) \u003d 187 kN.

Exterior walls

The operation of the internal forces \u003d 0.

The work of external forces \u003d 11.1 * (5.4 * 0.5 + 6 * 0.5) \u003d 61 kN.

Checking the overall condition for the impossibility of the formation of the second type mechanism

Verification is made according to the formula (2) of these recommendations

366 kN (excluding the operation of the pylon on the cut);

61 + 187 + 61 + 309 kN<366 кН.

The stability condition is made even without taking into account the operation of the pylon on the cut. The progressive collapse of the second type is impossible. In this case, you can repeat the purchase of the document using the button on the right.

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Introduction

The loss of individual carrier elements of the frame of its strength properties may result in a sequential inclusion in the collapse zone, an increasing number of carrier structures - the "Domino" effect will occur. A progressive or avalanche-like collapse is the collapse of the construction of the building (or its parts height of two or more floors), which have lost their support as a result of the local destruction of any floor. The relative term is the vitality - the ability of the technical device, structures, means or systems to perform their main functions, despite the damage gained, or adapting to new conditions. In the modern world, the risk of avalanche-like destruction is significant, therefore there is a need for accurate calculated algorithms, new reliable and economically appropriate methods of constructive strengthening of the carrier frame of the building, a clear legislative regulation of design and calculation, taking into account possible proceitable effects.

purpose of work

The aim of the work is a review of modern Russian and foreign publications related to the subject of calculation on the progressive collapse in a linear and nonlinear formulation of the problem, an analysis of Russian legislation relating to the survivability of carrier structures; Detection of the most likely causes of the progressive collapse of buildings.

Causes of progressive collapse

When developing constructive solutions, it is necessary to take into account not only the standard working conditions of the design, but also possible emergencies. The progressive collapse may arise as a result of emergency situations or technogenic effects divided into power, deformation and corrosion.

Possible technogenic causes of local damage may be:

blurry of the soil base as a result of accidents on internal or external drainage;
flooding of territories of natural waters;
destruction of part of structural elements from exposure to explosions, blows or local overload due to violation of the rules of operation;
the destruction of individual structures as a result of a significant reduction in the strength of materials, defects in the construction and action of corrosion.

An example is the collapse of the 9-storey large-passenger house on March 6, 1982 in Volgodonsk. The reason for the full collapse of the large-pointed residential building was a poorly embossed solution for freezing a horizontal stride formed due to the replacement of the basebar. At the time of thawing the solution there was a loss of the stability of the wall panel, as a result of which all 9 floors of a large-pastel buildings were collapsed.

errors made at the design stage (for example, a 24-ton visor of the metro station Sennaya Square collapsed on June 10, 1999 due to improperly designed fastening).

At all stages of the life cycle of structures (surveys, project, construction, operation, disassembly), errors can lead to progressive collapse.

Emergency situations capable of causing an avalanche-like building of the building are:

fire,
collision with the building of vehicles or flying objects,
gas explosion.

In addition, the risk of collapse cannot be completely excluded due to the heterogeneity of the strength and other technical properties of building materials, the uncertainty of the system requirements, the impossibility of ideal system modeling even using all the possibilities of modern software complexes. The most common forms of destruction of metal structures are the loss of stability and fragile destruction due to the uncontrolled development of the microcrack of the material. The progressive collapse of the entire structure of the bridge can begin with one microcrack in the metal of the supporting structures, and therefore it is necessary to study the strength properties of materials from the point of view of the theory of reliability.

History of study of progressive collapse

The starting point for the progression of the progressive collapse can be considered the sixteenth of May 1968: in London, due to the explosion of household gas, the twenty-ton-storey house Ronan Point (Ronan Point) was completely destroyed, see Figure 1. 22 people became victims of the accident. Partial collapse of Ronan Point led to serious changes in the legislation: the first of them became the fifth amendment to the construction standards (in Part A) of the United Kitlapse in 1970 (disproportional collapse). The amendment contained the requirements according to which the building should not be destroyed, a disproportionate crash, in other words, required preventing the progressive collapse of buildings.

Figure 1. Destruction of the house Ronan Point (Ronan Point)

The most famous case of the progressive structural collapse is the destruction of the World Trade Center in New York, which occurred in the eleventh of September 2011 as a result of a terrorist attack. The destruction of the WTC led to the catastrophic consequences: 2751 people became victims. A deliberate collision with Boeing 767-222 was not the first terrorist act in the WTC: Twenty-sixth of February 1993, an explosion of a car loaded by 680 kg of explosives was carried out on the underground parking lot of the Northern Tower, more than a thousand people were victims: six were killed, more than a thousand were injured . Due to the high strength of the frame of the building, the destruction of the supporting structures in 1993 did not occur.

The problem of progressive collapse has not bypassed Russia. In modern Russia, the most common cause of accidents capable of entrusting the progressive collapse is the explosion of household gas that occurred by the negligence of users. Already in 2013, Russia gasification was 65.3%, and therefore, for most residential houses, the risk of progressive collapse is essential.

Examples of such accidents can be:

October 13, 2007 as a result of the accident on Mandrykovskaya Street, 127 in Dnepropetrovsk - housing lost 417 people;
On February 27, 2012, the central part of the nine-story house was collapsed in Astrakhan;
On December 20, 2015, Cosmonavtov Street, 47 in the Dzerzhinsky district of Volgograd - the investigation of the explosion was the collapse of the entire entrance of the nine-story house.

In 2016, more than five major accidents associated with the domestic gas explosion occurred.

The largest accidents in Russia were:

full destruction of two central entrances in the house on the street. Guryanova (Moscow, 1999);
the explosion of household gas entailed the complete destruction of the seventeen-storey part of the house on the street Dvinsky (St. Petersburg, July 2, 2002);
coating collapse Water Park "Tranval Park" (Moscow, 2004).

Thousands of people became victims of such a catastrophe, and these tragedies could be avoided.

Review of Russian regulatory documentation regarding the calculation of progressive collapse

Obviously, the accounting of a possible emergency will entail a significant increase in the cost of designing and construction, so only a few developers go to it voluntarily. Therefore, a clear regulatory documentation is required, strictly regulating the need and composition of the calculation. Most of the modern foreign standards are not focused on preventing essential destruction, but to ensure the safety of people and the possibility of their timely evacuation.

Unfortunately, at present, there is practically no such documentation in Russia. Only strict recommendations on the composition and calculation algorithm can prevent the disastrous consequences of possible emergencies. A significant variety of Russian legislation in the field of construction is the lack of clear regulatory documents governing the design of buildings, taking into account the resistance to the progressive collapse and establishing requirements for the calculation of the carrier building frame. The document of the highest legal force in the field of providing building structures is the Federal Law No. 384-FZ. Article 16.6 approves the need for calculating for buildings and structures of an increased level of responsibility, to which, in accordance with the Urban-Planning Code, refer to technically complex, especially dangerous and unique objects. The list of buildings to be calculated is most fully listed in GOST 27751-2014. Reliability of building structures and grounds. Basic provisions (paragraph 5.2.6) The calculation is required for the COP-3 and CO-2 buildings under the condition of a large cluster of people whose list is specified in Appendix B. Thus, from July 1, 2015, the calculation is required for most public and residential buildings.

Although accounting of progressive collapse is required for an increasing number of buildings, there is still no clear algorithm for calculating, specific recommendations for the choice of accident zone. Similarly, questions arise from the selection of the necessary number of destroyable carrier elements. All these issues are covered in a wide range of recommendations for the design, issued by the MNIITEP and NIIZB in the 2000s, standards of organizations, but none of these documents have legislative force.

The most significant gap exists in the field of steel frame calculations to ensure their survivability. Existing documentation (MDS 20-2.2008; Hundred 36554501-024-2010) belongs only to the Bolshevolnaya facilities.

The regulatory documentation approves the need to evaluate the survivability of the carrier frame for all reinforced concrete monolithic buildings (clause 6.2.1. SP 52-103-2007), but no methodological instructions are given, in addition to the recommendation to calculate the method of finite elements using software certified in Russia complexes (p. 6.3.7.). Many software complexes have a built-in calculation module for a progressive collapse, however, the calculation results are not yet confirmed and require an additional experimental justification. The developers of the SCAD and Lira program complexes offer their calculation techniques (see Figure 2), however, the accuracy of the results obtained has not yet been confirmed and requires research in this direction.

Figure 2. Display of calculation results when using the "Progressive collapse" module SCAD PC

large-pointed buildings;
residential buildings of frame type;
residential buildings with carrier brick walls;
monolithic residential buildings;
high-rise buildings;
bolshnaya facilities.

These recommendations are similar in the part of the algorithm for calculating building structures, significant differences appear only in terms of recommendations on the measures of constructive enhancement of the framework, which is associated with significant differences in the work of the framework of stone and metallic materials. According to all modern regulatory acts, only the calculation of the first group of limit states is required, the definition of maximum movements and deflection is not required. The selection of the most dangerous in the point of view of the destruction of the element is carried out by analyzing the constructive scheme and the calculation results for several options for an emergency. In the regulatory documentation, there are no indications relating to the need to take into account the nonlinear work of the structures, which can have a strong effect on the correctness of the calculation results, since with the progressive destruction, the structural elements often have significant movement module that can entail significant changes in the design of structures. Thus, it can be argued that now in Russia there is an active work on the development of a regulatory framework for settlements for the progressive collapse, the circle of buildings and structures, which requires accounting for a possible accident, in addition, is building more and more high-rise buildings for which the probability accounting is built. Avalanche-like collapse is especially important. And therefore, it can be argued that, to achieve accurate results, the calculation algorithm and software will be constantly improved. The relevance of the study of progressive collapse confirms the widespread of modern scientists to ensure the strength and survivability of building structures in the conditions of proceitable effects, the work of engineering structures in the elastic-plastic stage.

Now in Russia and the CIS countries, project institutions are engaged in this issue as: MNIITP, NIIBZ, NIS. The result of many years of work of the Institutes of MNIITEP and NIIBZ is the recommendations issued in the 2000s to protect various types of buildings from avalanche-like collapse. Niracle specialists have developed DBN B.2.2-24.2009 "Design of high-altitude and civil buildings", containing a methodology for calculating a high-rise building for a progressive collapse, in Ukraine the methodology is a recommendatory nature.

Overview of the works of modern scientists dealing with the issue of progressive collapse

Many authors were studying the Russian and foreign legislative framework. Reviews can be found at V.Yu. Gracheva, TA Verchinina, A.A. Puzatkin; Zh.S. Jumagulova and A.K. Stamaliyeva, A.V. Pererrmutiver, and in. Scientists argue that further work on the regulatory framework is required: its refinement and expansion.

In addition to research institutes, individual scientists have made a huge contribution to the development of the problem of progressive collapse. IN. Diamond has developed a classification of types of progressive collapse, gave recommendations on the calculation algorithm, proposed cost-effective versions of constructive buildings; The scientist explored the dynamic effect of progressive collapse on the example of multi-storey reinforced concrete frames when removing one of the carrier columns of the first floor. He suggested a methodology for calculating the dynamism coefficient depending on the frame of the frame, which allows to solve the problem in static production.

No less acute than the question of legislative regulation of calculation and design, the question of the generally accepted approach to ensuring the strength of the framework of buildings during the foreclosable effects is worthwhile. It is impossible to accurately predict the place of the application and the value of the extreme load, similarly unpredictable defects of the installation and manufacture of building structures, deviations in the properties of materials - all this not only complicates modeling, but also makes absolutely accurate calculation. In this regard, many authors are engaged in issues of constructive decisions that contribute to the preservation of the structural integrity of the building, forecasting the most likely emergencies and their consequences.

Computer calculation of the model on avalanche-like destruction is complicated by the impossibility of using the final element method due to the lack of accurate data on the behavior of the structure under the progressive collapse and sufficient experience of building structural integrated models and interpretation of the results of calculations. Developments are needed to develop an improved methodology for assessing the vulnerability of constructive systems and their improvement to mitigate progressive collapse in various hazardous versions. Engineers need methods of design and calculations that can prevent the potential danger of the progressive collapse of buildings. The development of such methods is actively conducted by many scientists.

In emergency situations, materials work out of the stage of elastic deformations, and accounting for significant movements arising in the supporting structures. Significant modulus of deformation is able to entail the redistribution of loads, which means a change in the entire calculation scheme. Thus, when calculating the progressive collapse, accounting for the geometric and physical nonlinearities of the work of the carrier frame of the building is required. Work is underway in this area. The constant improvement of computer equipment allows you to build more and more detailed models of structures and contributes to becoming increasingly disseminating tasks in nonlinear formulation. Evaluation of the correctness of settlement models, checking the results of computer calculations, the art of interpretation of the results obtained is one of the central problems of not only the calculations on the progressive collapse, but also the entire construction as a whole. The project and research institutes and the developers of modern settlement programs are also involved in these issues, which contributes to the continuous improvement of software complexes. Analysis of the possibilities of the method of finite elements, examples of calculating models of buildings and new computational algorithms are also reflected in the works of Russian and foreign scientists.

Conclusion

Due to the ever-growing number of accidents causing disproportionate destruction of buildings, there is a need for accurate calculated algorithms, new reliable and economically expedient methods of constructive strengthening of the carrier building frame, clear legislative regulation of design and calculation, taking into account possible proceitable effects.

The work presents the history of the emergence and development of the problem of the progressive collapse of buildings, a review of modern Russian and foreign publications belonging to the subject of the calculation on the progressive collapse in a linear and nonlinear formulation of the problem, an analysis of Russian legislation relating to the survivability of carrying structures. The most likely reasons for the progressive collapse of buildings were also analyzed.

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In the Department of Town Planning and Architecture of the Ministry of Construction and Housing and Communal Services of the Russian Federation, within the framework of competence, a letter was reviewed on the requirements of regulatory and technical documents, and the following is reported.

The term "carrier structures" is practically not used in regulatory documents, since the definition of carrying structures is given in textbooks on construction mechanics and is understandable for each designer. The definition of the bearing capacity is established only in the SP 13-102-2003 * "Rules of examination of the supporting structures of buildings and structures" (hereinafter - SP 13-102-2003), which is currently not current standardization documents. According to SP 13-102-2003 * Bearing structures are building structures that perceive operational loads and exposure and ensuring the spatial stability of the building.

In accordance with the provisions of GOST 27751-2014, the reliability of building structures and grounds. The main provisions "The calculation on the progressive collapse is carried out for buildings and structures of the CS-3 class, as well as (on a voluntary basis) of buildings and structures of the CS-2 class.

The requirement to calculate the progressive collapse of all production buildings established in paragraph 5.1 of the SP 56.13330.2011 "SNiP 31-03-2001" Production buildings "(hereinafter - SP 56.13330.2011) is redundant and contrary to Federal Law No. 384-FZ" Technical Regulations on the safety of buildings and structures. This requirement will be corrected in 2018 by making a change in SP 56.13330.2011.

In 2017, JV 296.1325800.2017 "Buildings and structures. Special impacts "(hereinafter - SP 296.1325800.2017), which comes into force on February 3, 2018 for applying on a voluntary basis. In this arrow, it is indicated that when designing structures, scenarios of the implementation of the most dangerous emergency settlements should be developed and strategies have been developed to prevent the progressive collaration collaration with the local destruction of the structure. Each scenario corresponds to a separate special combination of loads and, in accordance with the instructions of the SP 20.13330.2011 "Snip 2.01.07-85 *" Loads and Impact "(hereinafter - SP 20.13330), should include one of the normalized (project) special impacts or One variant of local destruction of carrying structures for emergency special impacts. The list of emergency settlement scenarios and their corresponding special impacts is established by the Customer in the design task in coordination with the General Projector.

For each scenario, the bearing elements should be determined, the failure of which entails the progressive collapse of the entire structural system. To this end, it is necessary to analyze the design of the structure under the action of special combinations of loads, in accordance with the instructions of the SP 20.13330.

In paragraph 5.11, SP 296.1325800.2017 Conditions are indicated under which emergency exposures are allowed to be taken into account:

Developed special technical conditions for the design of the structure;

Scientific and technical support was conducted at all stages of design and construction of the structure, as well as the manufacture of these elements;

Calculation of structures on the action of design (normalized) special impacts specified in the joint venture 296.1325800.2017, the task of design and existing regulatory documents;

Additional coefficients of work conditions were introduced, lowering the calculated resistances of these elements and the nodes of their attachment (for the Bolshevolnaya facilities, the specified additional coefficients of the work are shown in the application in the specified joint venture);

Organizational events were held, including in accordance with the SP 132.13330.2011 "Ensuring the anti-terrorist protection of buildings and structures. General design requirements ", and agreed with the customer (see Appendix M of the specified Code of Rules).

Scientific and technical support is carried out by the Organization (organizations) other than those who develop project documentation. Scientific and technical support should conduct organizations (usually research) with experience in the relevant areas and the necessary experimental base.

Overview of the document

An explanation is given on the application of regulatory and technical documents when qualifying the supporting structures. In particular, the following is noted.

The term "carrier structures" is practically not used in regulatory documents, since the definition is given in textbooks on construction mechanics and is understandable for each designer. The definition of the concept of "bearing ability" is given.

In accordance with the provisions of GOST 27751-2014, the reliability of building structures and grounds. Basic provisions "Calculation of a progressive collapse is carried out for buildings and structures of the COP-3 class, as well as (on a voluntary basis) of buildings and structures of the CS-2 class.

In 2017, JV 296.1325800.2017 "Buildings and Constructions. Special impacts", which comes into force on February 3, 2018 for a voluntary basis. When designing structures, scenarios of the implementation of the most dangerous emergency settlement situations and strategies to prevent the progressive collaration collaration with local destruction of the structure should be developed. Each script corresponds to a separate special combination of loads. The list of emergency settlement scenarios and their corresponding special impacts is established by the Customer in the design task in coordination with the General Projector.

Corrected the procedure for scientific and technical support of work.

TsNIIPRomzdaniya MNIITP.

Standard organization

PREVENTION
Progressive
Reinforced concrete collapsions
Monolithic structures
Buildings

Design and calculation

STO-008-02495342-2009

Moscow

2009

Preface

The objectives and principles of standardization in the Russian Federation are established by the Federal Law of December 27, 2002 No. 184-FZ "On Technical Regulation", and the rules for the development and application - GOST R 1.4-2004 "Standardization in the Russian Federation. Standards of the organization. General. "

Information about standard

1. Developed and submitted by the Working Group as part of: D.T.N., prof. Granv V.V., Ing. Kelasyev N.G., Ing. Rosenbluma A.Ya. - Head of the topic, (OJSC TsNIipromzdania), Ing. Shapiro G.I. (State Unitary Enterprise "MNEITP"), D.T., Prof. Zalleov A.S.

3. Approved and commissioned by the Order of the General Director of OJSC TsNIipromzdaniy dated September 7, 2009 No. 20.

4. Entered for the first time

fromwrong

STO-008-02495342-2009

Standard organization

Preventing progressive collapse
Reinforced concrete monolithic buildings designs

Design and calculation

Date of administration - 09.09.2009

Introduction

Progressive collapse (pROGRESSIVE COLLAPSE. ) Indicates the consistent destruction of the building structures of the building (structures), due to the initial local damage to individual bearing structural elements and leading to the collapse of the entire building or its significant part.

The initial local damage to the structural elements of the building is possible with emergencies (gas explosions, terrorist attacks, vehicles, defects, construction, construction or reconstruction, etc.), not provided for by the conditions for normal operation of the building.

In the carrier system of the building, destruction is allowed in an emergency of individual carriers of structural elements, but these destruction should not lead to progressive collapse, i.e. The destruction of adjacent structural elements to which the load is transmitted, perceived earlier elements destroyed as a result of an emergency situation.

When developing the standard, the provisions of SNiP 2.01.07-85 * "Loads and Impact" (ed. 2003), SNiP 52-01-03 "Concrete and reinforced concrete structures. Basic provisions ", SP 52-101-2003" Concrete and reinforced concrete structures without pre-voltage of fittings "and STR 3655,4501-014-2008" Reliability of building structures and grounds. Basic provisions. "

1 area of \u200b\u200buse

1.1 This standard standard establishes the rules for the design of the reinforced concrete monolithic structures of residential, public and industrial buildings to be protected from progressive collapse in emergency situations.

1.2 to objects whose destruction can lead to large social, environmental and economic losses and when designing which the progressive collapse must be ensured:

a) building residential height over 10 floors;

b) public buildings * with a residence of 200 people. and more simultaneously within the block limited by deformation seams, including:

Educational appointment;

Health and social services;

Service (trade, food, domestic and communal service, communication, transport, sanitary service);

Cultural and leisure activities and religious rites (physical education and sports, cultural and educational and religious organizations, spectacular and leisure and entertainment organizations);

Administrative, etc. Appointments (governing bodies of the Russian Federation, subjects of the Russian Federation and local self-government, offices, archives, research, design and design organizations, credit and financial institutions, judicial legal institutions and prosecutor's office, editorial and publishing organizations);

For temporary stay (hotels, sanatoriums, hostels, etc.).

c) production and auxiliary buildings with a residence of 200 people. And more simultaneously within the block limited by deformation seams.

*) Classification of public buildings for the purpose is given in SNiP 2.08.02-89 * "Public buildings and structures" and Snip 31-05-2003 "Public administrative buildings".

1.3 Life support objects of cities and settlements, as well as especially dangerous, technically complex and unique objects **) should be designed in accordance with special specifications.

**) The classification of particularly dangerous, technically complex and unique objects is given to the City Planning Code of the Russian Federation, Art. 48 1.

1.4 With regard to a specific object, the requirement to prevent progressive collapse in emergency situations is made in accordance with the design assignment agreed in the prescribed manner and approved by the Customer and / or Investor.

2 Terms and Definitions

2.1 Progressive collapse - sequential destruction of the supporting structures of the building (structures), due to the initial local damage to individual carrying structural elements and leading to the collapse of the entire building or its significant part (two or more spies and two or more floors).

2.2 Normal building operation - Operation in accordance with the conditions provided for by SNiP 2.01.07-85 and SNiP 52-01-03.

2.3 Primary Constructive Building System - a system adopted for the conditions of normal operation of the building.

2.4 The secondary design system of the building is a primary constructive system, modified by excluding one vertical bearing structural element (columns, pilasters, sections of the wall) within one floor.

3 Basic provisions

3.1 The structural system of the building should not be subject to progressive collapse in the event of local destruction of individual structural elements in emergency situations that are not provided for in the conditions of normal operation of the building. This means that with a special combination of loads, local destruction of individual elements of the structural building system are allowed, but these destruction should not lead to the destruction of other structural elements of the changed (secondary) structural system.

3.2 The prevention of the progressive building collapse should be provided:

A rational constructive planning solution of the building, taking into account the likelihood of an emergency;

Constructive measures that increase the static uncement of the system;

The use of constructive solutions to ensure the development of structural elements and their compounds of plastic (inelastic) deformations;

The necessary strength of the carrying structural elements and the resistance of the system for the conditions of normal operation of the building and for cases of local destruction of the individual structural elements of the building.

3.3 When designing a building, along with calculations for normal operation, should be:

Static calculations of the modified structural systems of the building were produced with constructive elements (secondary constructive systems) and, accordingly, the modified calculation schemes for the action of a special combination of loads. The calculation of the bases should be performed only on the bearing capacity for the conditions provided for by paragraph 2.3. SNiP 2.02.01-83 *;

The reserves of the stability of secondary structural systems are established and in their insufficiency, the dimensions of the section of the elements or a constructive-planning solution of the building are increased;

Defined in conjunction with the results of the calculation for the conditions of normal operation, the required class of concrete and reinforcement of structural elements.

3.4 As a hypothetical local destroy, the destruction should be considered within one (each) floor of the building alternately one (each) column (pylon) or a limited portion of the walls.

3.5 The conditions for ensuring the progressive collapse of the secondary structural building systems are:

Unbreakable in the structural elements of values \u200b\u200bof force (voltages) defined with the values \u200b\u200bof the software loads, with respect to the efforts (voltages) in them, determined with the limit values \u200b\u200bof the characteristics of materials using the appropriate reliability coefficients;

Unassignment of reducing the system of stability of the system relative to the ratio of sustainability γ S \u003d 1.3.

In this case, the reliability coefficient by responsibility should be taken equal γ N \u003d 1.0, unless otherwise provided in the design task.

Displacement, cracking and deformation of the elements are not limited.

4 Constructive - planning solutions

The rational constructive - planning solution of the building in terms of preventing the progression of the progressive collapse is a constructive system, providing when disposing of a separate (any) vertical carrying structural element of the building, the conversion of structures over the retired element in the "suspended" system capable of passing the load on the preserved vertical structures.

To create such a constructive system should be provided:

Monolithic conjugation of overlap designs with reinforced concrete vertical structures (columns, pilasters, external and inner walls, staircase fences, ventilation mines, etc.);

Reinforced concrete monolithic belts around the perimeter of overlaps, combined with overlapping structures and performing the functions of the suponic jumpers;

Reinforced concrete monolithic parapets combined with coating designs;

Reinforced concrete walls in the upper floors of the building or reinforced concrete beams in the coating, combining columns (pilasters) among themselves and with other vertical reinforced concrete structures (walls, staircases of staircases, ventilation mines, etc.);

Operactions in reinforced concrete walls are not on the entire height of the floor, leaving, as a rule, the plots of deaf walls above the openings.

5 Loads

5.1 The calculation of secondary constructive systems to prevent progressive collapse should be carried out on a special combination of loads, including the regulatory values \u200b\u200bof constant and long-acting time loads, with a combination coefficient equal Ψ = 1,0.

5.2 For permanent loads, the weight of the carrier reinforced concrete structures should be attributed, the weight of the building parts (floor, partitions, suspended ceilings and communications, hinged and self-supporting walls, etc.) and side pressure on the weight of the soil and weight of the road surface and sidewalks.

5.3 To long-term temporary loads should be attributed to:

Reduced loads from people and equipment in the table. 3 Snip 2.01.07-85 *;

35% of the total regulatory load from vehicles;

50% full standard snow load.

5.4 All loads should be considered as static with a reliability coefficient for load γ F. = 1,0.

6 Characteristics of concrete and reinforcement

6.1 When calculating reinforced concrete structural elements to prevent progressive collapse should be taken:

a) the calculated values \u200b\u200bof concrete resistance to axial compression equal to their regulatory values \u200b\u200bmultiplied for structures concreted in a vertical position to the coefficient of working conditions γ B. 3 = 0,9;

b) the calculated values \u200b\u200bof concrete resistance to axial stretching used in the calculation of the transverse forces and the local action of loads equal to their regulatory values \u200b\u200bdivided by the reliability coefficient by concrete γ N. = 1,15;

c) the calculated values \u200b\u200bof the resistance of the longitudinal reinforcement structures of stretching equal to their regulatory values;

d) the calculated values \u200b\u200bof the resistance of the longitudinal armature of compression designs equal to the regulatory values \u200b\u200bof resistance to stretching, with the exception of the A500 class reinforcement for which R S. \u003d 469 MPa (4700 kgf / cm 2), and class fittings in 500 for which R S. \u003d 430 MPa (4400 kgf / cm 2);

e) the calculated values \u200b\u200bof the resistance of the transverse fittings for tensile structures equal to their regulatory values \u200b\u200bmultiplied by the coefficient of working conditions γ S. 1 = 0,8;

e) regulatory values \u200b\u200bof resistance of concrete and reinforcement, as well as values \u200b\u200bof the modulus of reinforcementE S. and the initial module of the elasticity of concreteE B. SP 52-101-2003.

7 Calculation

7.1 The calculation of the secondary structural systems of the building to prevent progressive collapse should be made separately for each (one) local destruction.

It is allowed to calculate only the most dangerous cases of destruction, which can be the schemes with the destruction of alternately vertical bearing structural elements:

a) having the greatest freight area;

b) located at the edge of the overlap;

c) located in the corner,

and disseminate the results of these calculations to other sections of the structural system.

7.2 As an initial, the calculation scheme is made, adopted when calculating the primary structural building system for the conditions of normal operation, and turn it into a secondary system by eliminating alternately vertical bearing structural elements for the most dangerous cases of destruction. It is recommended to include structural elements, usually not taken into account when calculating the primary system.

7.3 As one excluded vertical supporting structure, a column (pylon) should be taken or a portion of intersecting or adjacent bearing bearing walls. The total length of these parts of the walls is counted from the place of intersection or adjustment to the nearest opening in each wall or to conjugate with a wall of another direction, but not more than 7 m.

7.4 Vertical system designs should be considered rigidly pinched at the level of the foundations.

7.5 Static calculation Secondary systems should be made as an elastic system for certified software complexes (SCAD, LIRA, STARK - ES, etc.), taking into account geometric and physical nonlinearity. It is allowed to calculate only geometric nonlinearity.

When calculating, taking into account the geometric and physical nonlinearity, the rigidity of the cross sections of the structural elements should be taken in accordance with the instructions of the SP 52-101-2003, taking into account the duration of the validity of the loads and the presence or absence of cracks.

When calculating, taking into account only geometric nonlinearity, the rigidity of the cross sections b of structural elements should be determined as a product of the proportionality module E Pr. At the moment of inertia of reinforced concrete section J B..

Module proportionality E Pr. You should take:

when determining efforts - E Pr. = 0,6E B. E Pr. = E B. for vertical elements;

When calculating sustainability - E Pr. = 0,4E B. for horizontal elements and E Pr. = 0,6E B. For vertical elements

7.6 Calculation of the cross sections of the structural elements should be made in accordance with the benefit on efforts defined as a result of static calculation by accepting them short-term.

7.7 As a result of the calculation of the primary and secondary constructive systems, the efforts (voltage) in the structural elements are determined, the resulting concrete class and the reinforcement of elements and nodes of their conjugations are assigned and the stability margin of the framework of the framework is established, and during its insufficiency, the size of the sections of the elements or the design solution of the building increases.

8 Constructive requirements

8.1 Construction of elements and their conjugations should be made in accordance with the benefit and SP 52-103-2007.

8.2 Class of concrete and reinforcement of structural elements should be prescribed to the largest comparison of the calculations for the conditions of normal operation of the building and to prevent progressive collapse.

8.3 In reinforcement of structural elements, special attention should be paid to the reliability of the anchoring of reinforcement, especially in the places of intersections of structural elements. The lengths of the anchoring and the overlap of reinforcement rods should be increased by 20% relative to the required software.

8.4 Longitudinal fittings of structural elements must be continuous. The area of \u200b\u200bthe cross-section of longitudinal reinforcement (separately lower and separately top) slabs of boiling off overlappings and beams of beam overlaps should be at least μ s, min \u003d 0.2% of the cross section of the element.

8.5 Longitudinal reinforcement of vertical bearing structural elements should perceive the stretching force of at least 10 kN (1 TC) for each square meter of the cargo area of \u200b\u200bthis structural element.

An example of calculating the framework of the building to prevent progressive collapse *)

*) Compiler Ing. A.P. Chernomaz

Building of a hotel-office complex of a variable floor (s). The largest number of aboveground floors 14, underground - 1. The maximum size in terms of 47.5 × 39.8 m. Located in the Moscow region. Wind DistrictIB, snow area III.

The building frame with a central staircase-lift core of rigidity and two side staircase cells. The strength, stability and rigidity of the frame of the building is provided by the discs of overlapping and the system of columns and walls embedded in the foundation.

The main column grid is 7.5 × 7.2 m. Square cross sections columns from 400 × 400 to 700 × 700 mm. Overlap of a breakless thickness of 200 mm with capitals.

Frame designs (columns, overlap), foundations, stairs, walls of staircases, elevator and communication mines, outer walls of underground and XI (technical) floors, partially, the inner walls are monolithic reinforced concrete walls. Concrete class B30, longitudinal working fittings class A500C.

To prevent progressive collapse in emergency, special structural elements are provided (reinforced concrete walls around the perimeter of technicalXI floor, wall on axis 11 starting withXII. floor and to the coating, the wall along the axis 1 starting withX. The floors and to the coating), ensuring along with the structural elements necessary for the functioning of the building during normal operation, the conversion of structures into the "suspended" system over hypothetically accommodated columns on the perimeter of the building and, partly, media. Zones around the middle columns that do not turn into "suspended" systems during the destruction of these columns in the event of an emergency impact, if necessary, reinforced (see below).

The design scheme of the building was adopted as a spatial system from the columns and walls embedded in the foundation, combined with overlaps and stairs (). Calculation is made according to the software packageSCAD Office 11.3.

In terms of liability, the building is related to the I-MU (elevated) level. The reliability coefficient is responsible to be taken equal γ N.= 1.1 for the main combination of loads.

The calculation of the framework of the building is made on the main combination of loads for the operation stage (primary structural system) and on a special combination of loads for preventing progressive collapse (secondary structural systems).

The magnitudes of the loads are shown in Table. 1 and 2.

Table 1

A place	Vertical loads of vehicles / m² (without its own weight)
	regulatory			calculated
	permanent	temporary		basic combination					special combination
		full	including Loins.	permanent	temporary by
					overlapping.		frame
					full	duration	full	loins.
Overlapping	0,15+0,45+0,04 = 0,64 (floor, partitions, suspension)		0,07	0,18+0,50+0,05 = 0,73	0,24	0,09	0,12	0,09	0,64+0,07 = 0,71
Pok. Exp.	0.39 (roofing, suspension)	0.13 (Snow)	0,07	0,48	snow bag	0,09	0,20	0,09	0,39+0,07 = 0,46

The load from the outer walls is adopted equalq. N. = 0,4 tC / m² walls and q R.\u003d 0.56 TC / m² walls.

table 2

No. N / N	Load application location	View of the calculation	*Combinations of calculation vertical loads (without their own weight), Tc / m ² )**
No. N / N	Load application location	View of the calculation	basic	special
	on overlapping		(0.73 + 0.12) · 1.1 \u003d 0.94	0,71
	on overlapping	calculation of overlapping	(0.73 + 0.24) · 1.1 \u003d 1.07	0,71
	Operated coating	calculation of the foundation, columns and frame	(0.48 + 0.2) · 1.1 \u003d 0.75	0,46
	Operated coating	calculation of coating	(0.48 + snow) · 1,1	0,46
	from wall	calculation of all designs	0,56∙1,1 = 0,62	0,40

*) - The values \u200b\u200bof all loads, except for the walls, are given on m² overlapping and coatings, and from walls - on m² walls.

The values \u200b\u200bof the estimated resistance of reinforcement and concrete are given in Table. 3.

Table 3.

Type of construction	The effort and nature of reinforcement	Estimated immature resistance, kgf / cm² for a combination of loads		Calculated concrete resistance, kgf / cm² for combination of loads
Type of construction	The effort and nature of reinforcement	basic	special	basic	special
Overlapping		R s \u003d 4430	R SN \u003d 5100	Compression R b \u003d 173	Compression R bn \u003d 224
Overlapping	Class A240 transverse fittings	R SW \u003d 1730	R SN · γ S. 1 = 2450 · 0.8. = 1960	Stretching R bt \u003d 11.7	Stretching
Columns, Wall Pilastry	Compression of longitudinal fittings class A500C	R sc \u003d 4080	R s \u003d 4700	compression R B.· γ B3. = 173 · 0.9 = 156	compression R BN.· γ B3. = 224 · 0.9 = 202
Columns, Wall Pilastry	Stretching longitudinal fittings class A500C	R s \u003d 4430	R SN \u003d 5100	compression R B.· γ B3. = 173 · 0.9 = 156	compression R BN.· γ B3. = 224 · 0.9 = 202

Table 4.

Frame element	Initial modulus of elasticity Beton E b × 10 -6 Tc / m²	Deformation module E PR when calculating Tc / m² × 10 -6
		efforts and reinforcement of elements	sustainability
		efforts and reinforcement of elements	on the main combination of loads	on a special combination of loads
Plates of overlaps	3,31	3.31 · 0.6 \u003d 2.0	3.31 · 0.2 \u003d 0.66	3.31 · 0.4 \u003d 1.3
Beams	3,31	3.31 · 0.6 \u003d 2.0	3.31 · 0.2 \u003d 0.66	3.31 · 0.4 \u003d 1.3
Columns	3,31	3,31	3.31 · 0.3 \u003d 1.0	3.31 · 0.6 \u003d 2.0
Walls	3,31	3,31	3.31 · 0.3 \u003d 1.0	3.31 · 0.6 \u003d 2.0

Modules of deformation of reinforced concrete structures are taken in Table. four.

When calculating secondary constructive systems on a special combination of loads, there are cases of exception alternately medium column No. 14, the estate column number 21 and the angular column No. 23 onI. and XIII floors (see,)

Calculations have shown that compared with the primary structural system, with the exclusion of alternately specified columns, the stock of the overall stability of the building of the building is practically not changed, but there is an obvious redistribution of efforts in structures.

Some results of the calculations of primary and secondary systems when removing the column No. 14 are presented in Table. 5 and 6 and in fig. 5 ÷ 8.

Table 5.

№ № columns 4)	Estimated total area of \u200b\u200blongitudinal reinforcement columns, cm 2
	with primary structural system 1)		when removing columns No. 14 on I floor 2)		when removing the column number 14 at the XIII floor 2)		result
	I floor	XIII Floor 3)	I floor	XIII FLOOR	I floor	XIII FLOOR	I floor	XIII FLOOR
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