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1

Experimental and theoretical study of the reinforced concrete flat slabs with the central support loss

Tur Viktar, Tur Andrei, Lizahub Aliaksandr

Inżynieria Bezpieczeństwa Obiektów Antropogenicznych

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2022

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Nr 4

12--41

EN

The paper experimentally and theoretically considers the issues of assessing the robustness and resistance to progressive collapse of a flat slab with a sudden removal of the central support. The results of testing two scale models of a fragment of a flat ceiling in the case of removal of the central support under static (specimen FS-1) and dynamic (specimen FS-2) loading are presented and analyzed. A theoretical approach to the quantitative assessment of robustness was tested, which is based on the provisions of the energy balance of a damaged structural system in an accidental design situation.

2

Modeling damaged precast structural system when its robustness check

Tur Viktar, Tur Andrei, Lizahub Aliaksandr

Inżynieria Bezpieczeństwa Obiektów Antropogenicznych

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2021

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Nr 3

63--81

EN

Within the framework of traditional approaches to checking for resistance of reinforced concrete buildings and structures to the progressive collapse development, membrane (chain) forces in a damaged structural system are calculated separately, without considering its non-linear bending behavior during the formation of the plastic hinges and without checking the possibility of achieving large deflections. The authors propose an approach to modelling a nonlinear quasi-static reaction of a damaged structural system in an accidental design situation. This approach considers non-linear bending and the resistance of reserved horizontal ties, considering their ultimate ductility. The authors verified the proposed approach based on the results of experimental studies by others researchers. An example of the application of the proposed approach in assessing the robustness of a structural system made of precast concrete with a sudden removal of the central column is considered. In accordance with the provisions of the energy approach, an analysis is made of the contribution of individual resistance mechanisms to the total quasi-static and dynamic resistance of the damaged structural system. We show that the proposed calculation model adequately describes the behavior of a damaged structural system in an accidental design situation, and therefore to carry out parametric studies and check the robustness of building structures.

3

Simplified analytical method for the robustness assessment of precast reinforced concrete structural systems

Tur Viktar, Tur Andrei, Lizahub Aliaksandr

Budownictwo i Architektura

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2021

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Vol. 20, no 4

93--114

EN

The article presents the simplified implementation of alternative load path method based on the energy balance approach. This method should be used to check the global resistance of a damaged structural system after the occurrence of an accidental event. Basic assumptions of simplified analytical models for modelling resistance of horizontal ties in a damaged structural system, taking into account the membrane (chain) effects, were presented. An approach to modelling the dynamic resistance of a damaged structural system based on the energy balance method is described. Calculated dependencies for checking the robustness of a prefabricated multi-storey building with hollow-core slabs after the loss of the central column are proposed and considered using an example. On the considered example, a comparison of the required tie sections area with the dynamic resistance designed using the energy balance method (EBM) and according to the current standards, and a statistical assessment of the reliability of the load-bearing capacity models are carried out. In the end, a brief algorithm for the simplified calculation of the dynamic resistance of a damaged structural system is proposed.

4

Combinations of actions for accidental design situation: a review, analysis and propositions

Tur Viktar, Tur Andrei, Lizahub Aliaksandr, Derechennik Stanislav

Inżynieria Bezpieczeństwa Obiektów Antropogenicznych

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2020

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Nr 3

1--25

EN

The paper discusses two main design strategies when checking for reliability and considers accidental action combinations according the various codes. If accidental actions can be identified, one of the possible design strategies is checking the “key element”. This strategy minimizes the possibility of local failure and subsequent progressive collapse. The combination of actions for accidental design situation for checking of the “key-element” resistance was proposed. In addition, the values of the combination factors for variable loads and partial factors for permanent loads in accordance with required reliability class RC for structural element and values of accidental loads was proposed. The second strategy is checking modified structural systems in accidental design situation from unidentified accidental actions. For this case, a comparison of several probabilistic models was performed, as well as a probabilistic assessment of the accidental action combinations according the various codes.

5

An innovative safety format for structural system robustness checking

Tur Andrei, Tur Viktar, Derechennik Stanislav, Lizahub Aliaksandr

Budownictwo i Architektura

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2020

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Vol. 19, no 4

67--84

EN

The estimation of structural robustness remains one of the most important stages of the design of structural systems. Recommended design strategies for the robustness assessment are based on the provisions specified in the actual EN 1991-1-7 and ISO 2394:2015. Currently, the EN 1991-1-7 and ISO2394:2015 allows the use of indirect tie-force method, but normally, non-linear pseudo-static analysis is widely used, because it is based on more realistic constitutive relations for basic variables, which enables a simulation of the real structural behaviour. Implementation of the non-linear pseudo-static analysis for the assessment of a structural system in accidental design situations requires to adopt a different approach to safety format. The paper presents an innovative approach to safety format calibration for non-linear analysis of RC-structures subjected to accidental loads. The proposed method of the robustness estimation is based on the joint energy-saving (conversion) approach and the full probabilistic method for the estimation of a safety format for pseudo-static non-linear response of modified (damaged) structural system. The proposed probabilistic considerations are based on the Order Statistic Theory.

PL

Ocena odporności konstrukcji jest jednym z najważniejszych etapów projektowania konstrukcji budowlanych. Zalecane strategie projektowania odporności kontrukcji bazują na postanowieniach obowiązujących norm: EN 1991-1-7 i ISO 2394:2015. Obecnie normy EN 1991-1-7 i ISO2394:2015 pozwalają na użycie metody pośredniej więzi łączących (TF method), ale zwykle używana jest nielinearna analiza psedostatyczna, ponieważ bazuje na bardziej realistycznych związków konstytutywnych dla podstawowych zmiennych, co umożliwia symulację prawdziwego zachowania konstrukcji. Użycie nielinearnej analizy pseudostatycznej do oceny konstrukcji budowlanych w przypadku oddziaływań wyjątkowych wymaga użycia innego podejścia do formatu bezpieczeństwa. Artykuł przedstawia innowacyjne podejście do kalibracji formatu bezpieczeństwa dla nielinearnej analizy żelbetowych konstrukcji poddanych wyjątkowym obciążeniom. Proponowane metody oceny odporności na zniszczenie bazują na połączony podejściu energooszczędnym (konwersji) i pełnej metodzie probabilistycznej oceny bezpieczeństwa pseudostatycznej, nielinearnej odpowiedzi zmienionej (uszkodzonej) konstrukcji budowlanej. Zaproponowane rozważania bazują na statystykach porządkowych.