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Article
Publication date: 3 October 2019

Arash Naji

Progressive collapse refers to a phenomenon, in which local damage in a primary structural component leads to total or partial structural system failure, without any…

Abstract

Purpose

Progressive collapse refers to a phenomenon, in which local damage in a primary structural component leads to total or partial structural system failure, without any proportionality between the initial and final damage. Robustness is a measure that demonstrates the strength of a structure to resist progressive collapse. Static pushdown and nonlinear dynamic analysis were two main procedures to calculate the capacity of structures to resist progressive collapse. According to previous works, static analysis would lead to inaccurate results. Meanwhile, capacity analysis by dynamic analysis needs several reruns and encountering numerical instability is inevitable. The purpose of this paper is to present the formulation of a solution procedure to determine robustness of steel moment resisting frames, using plastic limit analysis (PLA).

Design/methodology/approach

This formulation utilizes simplex optimization to solve the problem. Static pushdown and incremental dynamic methods are used for verification.

Findings

The results obtained from PLA have good agreement with incremental analysis results. While incremental dynamic analysis is a very demanding method, PLA can be utilized as an alternative method.

Originality/value

The formulation of progressive collapse resistance of steel moment frames by means of PLA is not proposed in previous research works.

Details

International Journal of Structural Integrity, vol. 11 no. 2
Type: Research Article
ISSN: 1757-9864

Keywords

Article
Publication date: 30 May 2019

J. Esfandiari and Y. Khezeli

An analytical investigation is performed on zipper-braced frames. Zipper-braced frames are an innovative bracing system for steel structures. Conventional inverted-V-braced frames…

Abstract

Purpose

An analytical investigation is performed on zipper-braced frames. Zipper-braced frames are an innovative bracing system for steel structures. Conventional inverted-V-braced frames exhibit a design problem arising from the unbalanced vertical force generated by the lower story braces when one of them buckles. This adverse effect can be mitigated by adding zipper columns or vertical members connecting the intersection points of the braces above the first floor.

Design/methodology/approach

This paper critically evaluates over strength, ductility and response modification factors of these structures. To achieve the purpose of this research, several buildings of different stories are considered. Static pushover analysis, linear dynamic analysis and nonlinear incremental dynamic analysis are performed by OpenSees software concerning ten records of past earthquakes.

Findings

Also, ductility factor, over strength factor and response modification factor, has been calculated for zipper-braced frames system. The values of 3.5 and 5 are suggested for response modification factor in ultimate limit state and allowable stress methods, respectively.

Originality/value

The fragility curves were plotted for the first time for such kind of braces. It should be mentioned that these curves play significant roles in evaluating seismic damage of buildings.

Details

World Journal of Engineering, vol. 16 no. 3
Type: Research Article
ISSN: 1708-5284

Keywords

Article
Publication date: 2 November 2015

Ivan Balic, Ante Mihanovic and Boris Trogrlic

The purpose of this paper is to present a new modification of the multimodal pushover method, named the target acceleration method. The target acceleration is the minimum…

Abstract

Purpose

The purpose of this paper is to present a new modification of the multimodal pushover method, named the target acceleration method. The target acceleration is the minimum acceleration of the base that leads to the ultimate limit state of the structure, i.e., the lowest seismic resistance.

Design/methodology/approach

A nonlinear numerical model is used to determine the target acceleration, which is achieved using the iterative procedure according to the envelope principle. Validation of the target acceleration method was conducted on the basis of the results obtained by incremental dynamic analysis.

Findings

The influence of higher modes is highly significant. The general failure vector corresponding to the target acceleration differs from the first load vector and the form of the load with uniform acceleration according to the height of structure, as contained in the European Standard EN 1998-1. Comparison between the target acceleration, including the equivalent structural damping, and the failure peak ground acceleration obtained from the dynamic response of the structure exhibits notably good agreement. This result implies that the equivalent structural damping as calculated according to the formulation presented in this paper should be greater than that suggested in the literature.

Originality/value

The originally developed procedure named multimodal pushover target acceleration method can reasonably estimate the minimum acceleration of the base that leads to the ultimate limit state of the structure, and consequently provides a reliable tool for the assessment of the lowest seismic resistance.

Details

Engineering Computations, vol. 32 no. 8
Type: Research Article
ISSN: 0264-4401

Keywords

Article
Publication date: 20 April 2015

Sergiu Andrei Baetu, A H Barbat and Ioan Petru Ciongradi

The purpose of this paper is to investigate a dissipative reinforced concrete structural wall that can improve the behavior of a tall multi-storey building. The main objective is…

Abstract

Purpose

The purpose of this paper is to investigate a dissipative reinforced concrete structural wall that can improve the behavior of a tall multi-storey building. The main objective is to evaluate the damage of a dissipative wall in comparison with that of a solid wall.

Design/methodology/approach

In this paper, a comparative nonlinear dynamic analysis between a dissipative wall and a solid wall is performed by means of SAP2000 software and using a layer model. The solution to increase the seismic performance of a reinforced concrete structural wall is to create a slit zone with short connections. The short connections are introduced as a link element with multi-linear pivot hysteretic plasticity behavior. The behavior of these short connections is modeled using the finite element software ANSYS 12. In this study, the authors propose to evaluate the damage of reinforced concrete slit walls with short connections using seismic analysis.

Findings

Using the computational model created in the second section of the paper, a seismic analysis of a dissipative wall from a multi-storey building was done in the third section. From the results obtained, the advantages of the proposed model are observed.

Originality/value

A simple computational model was created that consume low processing resources and reduces processing time for a dynamic pushover analysis. Unlike other studies on slit walls with short connections, which are focussed mostly on the nonlinear dynamic behavior of the short connections, in this paper the authors take into consideration the whole structural system, wall and connections.

Details

Engineering Computations, vol. 32 no. 2
Type: Research Article
ISSN: 0264-4401

Keywords

Open Access
Article
Publication date: 31 October 2023

Hongping Xing, Yu Liu and Xiaodan Sun

The smoothness of the high-speed railway (HSR) on the bridge may exceed the allowable standard when an earthquake causes vibrations for HSR bridges, which may threaten the safety…

Abstract

Purpose

The smoothness of the high-speed railway (HSR) on the bridge may exceed the allowable standard when an earthquake causes vibrations for HSR bridges, which may threaten the safety of running trains. Indeed, few studies have evaluated the exceeding probability of rail displacement exceeding the allowable standard. The purposes of this article are to provide a method for investigating the exceeding probability of the rail displacement of HSRs under seismic excitation and to calculate the exceeding probability.

Design/methodology/approach

In order to investigate the exceeding probability of the rail displacement under different seismic excitations, the workflow of analyzing the smoothness of the rail based on incremental dynamic analysis (IDA) is proposed, and the intensity measure and limit state for the exceeding probability analysis of HSRs are defined. Then a finite element model (FEM) of an assumed HSR track-bridge system is constructed, which comprises a five-span simply-supported girder bridge supporting a finite length CRTS II ballastless track. Under different seismic excitations, the seismic displacement response of the rail is calculated; the character of the rail displacement is analyzed; and the exceeding probability of the rail vertical displacement exceeding the allowable standard (2mm) is investigated.

Findings

The results show that: (1) The bridge-abutment joint position may form a step-like under seismic excitation, threatening the running safety of high-speed trains under seismic excitations, and the rail displacements at mid-span positions are bigger than that at other positions on the bridge. (2) The exceeding probability of rail displacement is up to about 44% when PGA = 0.01g, which is the level-five risk probability and can be described as 'very likely to happen'. (3) The exceeding probability of the rail at the mid-span positions is bigger than that above other positions of the bridge, and the mid-span positions of the track-bridge system above the bridge may be the most hazardous area for the running safety of trains under seismic excitation when high-speed trains run on bridges.

Originality/value

The work extends the seismic hazardous analysis of HSRs and would lead to a better understanding of the exceeding probability for the rail of HSRs under seismic excitations and better references for the alert of the HSR operation.

Article
Publication date: 25 November 2020

Nibas Apu and Ravi Sinha

Increasing awareness of the society and complying with design requirements of building codes for seismic safety of structures and inhabitants during severe earthquakes are the…

Abstract

Purpose

Increasing awareness of the society and complying with design requirements of building codes for seismic safety of structures and inhabitants during severe earthquakes are the primary purpose of seismic analysis. This study aims to present the variability in seismic fragility functions for frames of different heights for the most vulnerable condition of structure using nonlinear time history analysis.

Design/methodology/approach

A total of 4, 8 and 20 stories reinforced concrete (RC) moment-resisting two-dimensional frames are considered for this study. Ground motions (GM) are selected as per the conditional mean spectrum and these are conditioned on a target spectral acceleration at the concern time period. RC frames are designed and detailed as per Indian standards. A concentrated plasticity approach is adopted for non-linear analytical modeling of the RC frames. Deterministic capacity limit states in terms of maximum inter-story drift ratio are considered for different damage states. Fragility functions have been derived following a lognormal distribution from incremental dynamic analysis curves. Finally, the maximum likelihood estimation of the response is obtained for fitting curves with observed fragility.

Findings

The fragility functions of the three structures reflect that under critical or extreme conditions of GM the taller buildings have higher fragility than the shorter buildings for each level of limit states even though both are designed to meet their code-level design forces.

Research limitations/implications

The study is conducted on the extreme scenario of GM conditioned on the fundamental time period of each building, whereas comparison can be developed by selecting various methodologies of GM set. The probabilistic capacity model can be developed for future studies to check the fragility variation with deterministic and probabilistic capacity.

Originality/value

The investigation endeavors to present a comprehensive fragility assessment framework by analytical method. The outcome will be useful in the development of a disaster management strategy for new or old buildings and the response of seismic force with a variation of the building’s height. The findings will also be useful for updating the earthquake-resistant building codes for the new building construction in a similar context.

Details

International Journal of Disaster Resilience in the Built Environment, vol. 12 no. 4
Type: Research Article
ISSN: 1759-5908

Keywords

Open Access
Article
Publication date: 3 October 2019

Lin Qi, Wenbo Zhang, Ronglai Sun and Fang Liu

Giant orthogonal grid barrel vault is generated by deleting members in the inessential force transfer path of the two-layer lattice barrel vault. Consisting of members in the…

1373

Abstract

Purpose

Giant orthogonal grid barrel vault is generated by deleting members in the inessential force transfer path of the two-layer lattice barrel vault. Consisting of members in the essential transfer path only, giant orthogonal grid barrel vault is a new type of structure with clear mechanical behavior and efficient material utilization. The paper aims to discuss this issue.

Design/methodology/approach

The geometrical configuration of this structure is analyzed, and the geometrical modeling method is proposed. When necessary parameters are determined, such as the structural span, length, vault rise, longitudinal and lateral giant grid number and section height to top chord length ratio of the lattice member, the structure geometrical model can be generated.

Findings

Numerical models of giant orthogonal grid barrel vaults with different rise–span ratios are built using the member model that can simulate the pre-buckling and post-buckling behavior. So the possible member buckle-straighten process and the plastic hinge form–disappear process of the structure under strong earthquake can be simulated.

Originality/value

Seismic analysis results indicate that when the structure damages under strong earthquake there are a large number of buckling members and few endpoint plastic hinges in the structure. Dynamic damage of giant orthogonal grid barrel vault under strong earthquake is caused by buckling members that weaken the structural bearing capacity.

Details

International Journal of Structural Integrity, vol. 11 no. 1
Type: Research Article
ISSN: 1757-9864

Keywords

Article
Publication date: 6 June 2022

Huizhong Xiong, Shengtang Jiang, Yong Huang and Jian Zhang

In order to explore the damage probability of bridge engineering in the event of earthquake in the construction stages, the analysis method of seismic vulnerability in the…

Abstract

Purpose

In order to explore the damage probability of bridge engineering in the event of earthquake in the construction stages, the analysis method of seismic vulnerability in the construction stages is proposed in this paper.

Design/methodology/approach

Based on the joint simulation function of construction stage conditions and seismic response conditions of MIDAS/Civil finite element analysis software, combined with the method of IDA analysis and compared the relationship between demand and capacity.

Findings

The research shows that: (1) the average seismic loss in different construction stages varies greatly; (2) the seismic vulnerability varies greatly in different construction stages. The vulnerability of the bridge in stage 6 is determined by the longitudinal direction of bridge. Therefore, during the construction of the whole bridge, we should focus on strengthening the disaster and loss prevention strategy of earthquake insurance in the longitudinal direction of bridge. (3) The application of the secondary dead load mainly affects the fragilityin the longitudinal direction of bridge, but has little effect on the fragility in the transversal direction of bridge.

Originality/value

This paper is to explore the seismic vulnerability of a typical simply supported continuous bridge during the construction stages, and to trace the entire construction stage of a typical simply supported continuous bridge. According to the characteristics of the system transformation in the actual construction steps, demand-capacity ratios were established based on incremental dynamic analysis (IDA) and performance indicators of moment curvature and stability, and the seismic vulnerability research is carried out for the construction stages prone to earthquake damage. Furthermore, it provides a basis for seismic risk assessment of such bridges in different construction stages.

Details

Multidiscipline Modeling in Materials and Structures, vol. 18 no. 3
Type: Research Article
ISSN: 1573-6105

Keywords

Article
Publication date: 5 August 2019

Payam Asadi and Hosein Sourani

In the absence of random variables, random variables are generated by the Monte Carlo (MC) simulation method. There are some methods for generating fragility curves with fewer…

Abstract

Purpose

In the absence of random variables, random variables are generated by the Monte Carlo (MC) simulation method. There are some methods for generating fragility curves with fewer nonlinear analyses. However, the accuracy of these methods is not suitable for all performance levels and peak ground acceleration (PGA) range. This paper aims to present a method through the seismic improvement of the high-dimensional model representation method for generating fragility curves while taking advantage of fewer analyses by choosing the right border points.

Design/methodology/approach

In this method, the values of uncertain variables are selected based on the results of the initial analyses, the damage limit of each performance level or according to acceptable limits in the design code. In particular, PGAs are selected based on the general shape of the fragility curve for each performance limit. Also, polynomial response functions are estimated for each accelerogram. To evaluate the accuracy, fragility curves are estimated by different methods for a single degree of freedom system and a reinforced concrete frame.

Findings

The results indicated that the proposed method can not only reduce the computational cost but also has a higher accuracy than the other methods, compared with the MC baseline method.

Originality/value

The proposed response functions are more consistent with the actual values and are also congruent with each performance level to increase the accuracy of the fragility curves.

Article
Publication date: 12 June 2017

Farshad Hashemi Rezvani, Behrouz Behnam, Hamid Reza Ronagh and M. Shahria Alam

The purpose of this paper is to determine the failure progression resistance of the steel moment-resisting frames subjected to various beam-removal scenarios after application of…

Abstract

Purpose

The purpose of this paper is to determine the failure progression resistance of the steel moment-resisting frames subjected to various beam-removal scenarios after application of the design earthquake pertinent to the structure by investigating a generic eight-story building.

Design/methodology/approach

The structure is first pushed to arrive at a target roof displacement corresponding to life safety level of performance. To simulate the post-earthquake beam-removal scenario, one of the beam elements is suddenly removed from the structure at a number of different positions. The structural response is then evaluated by using nonlinear static and dynamic analyses.

Findings

The results show that while no failure is observed in all of the scenarios, the vulnerability of the upper stories is much greater than that of the lower stories. In the next step, the structural resistance to such scenarios is determined. The results confirm that for the case study structure, at most, the resistance to failure progression in upper stories is 58 percent more than that of lower stories.

Originality/value

Failure and fracture of beam-to-column connections resulting in removal of beam elements may lead to a chain of subsequent failures in other structural members and eventually lead to progressive collapse in some cases. Deficiency in design or construction process of structures when combined by application of seismic loads may lead to such an event.

Details

International Journal of Structural Integrity, vol. 8 no. 3
Type: Research Article
ISSN: 1757-9864

Keywords

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