scholarly journals Progressive Collapse Assessment: A review of the current energy-based Alternate Load Path (ALP) method

2019 ◽  
Vol 258 ◽  
pp. 02012 ◽  
Author(s):  
Nur Ezzaryn Asnawi Subki ◽  
Hazrina Mansor ◽  
Yazmin Sahol Hamid ◽  
Gerard Parke
Keyword(s):  
Dynamic Analysis ◽  
Static Analysis ◽  
Progressive Collapse ◽  
Structural Response ◽  
Steel Frame ◽  
Collapse Mechanism ◽  
Load Path ◽  
Acceptance Criterion ◽  
Current Energy ◽  
Collapse Assessment

The Alternate Load Path (ALP) is a useful method that has generated a considerable recent research interest for the assessment of progressive collapse. The outcome of the ALP analysis can be assessed either using the force-based approach or the energy-based approach. The Unified Facilities Criteria (UFC- 4- 023-03) of progressive collapse guideline - have outlined that the force-based approach can either be analysed using static or dynamic analysis. The force-based approach using static analysis is preferable as it does not require a high level of skill and experience to operate the software plus no effort is required in scrutinising the validity of the analysis results output. However, utilising the static approach will eliminate the inertial effect in capturing the actual dynamic response of the collapsed structure. In recent years, the development of the energy-based progressive collapse assessment is attracting widespread interest from researchers in the field; as the approach can produce a similar structural response with the force-based dynamic analysis by only using static analysis. Most of the current energy-based progressive collapse assessments are developed following the requirements which are given in the progressive collapse guidelines provided by the Unified Facilities Criteria. However, little attention is given to the development of the energy-based approach using the Eurocode standards as a base guideline. This article highlights the merits of utilising the energy-based approach against the force-based approach for a collapsed structure and explains the collapse mechanism of a steel frame in the perspective of the energy concept. The state of the art of energy-based progressive collapse assessment for a structural steel frame is reviewed. The comprehensive review will include insights on the development of the energy-based method, assumptions, limitations, acceptance criterion and its applicability with the European standards. Finally, potential research gaps are discussed herein.

scholarly journals Progressive Collapse Analysis of Reinforced Concrete Structures: A Simplified Procedure

2017 ◽  
Vol 2 (10) ◽  
pp. 7 ◽  
Author(s):  
Arash Naji ◽  
Mohamadreza Rohani
Keyword(s):  
Reinforced Concrete ◽  
Dynamic Analysis ◽  
Static Analysis ◽  
Progressive Collapse ◽  
Concrete Structures ◽  
Nonlinear Static Analysis ◽  
Reinforced Concrete Structures ◽  
Collapse Analysis ◽  
Nonlinear Static ◽  
Progressive Collapse Analysis

In this paper, a simplified analysis procedure to calculate the column removed point displacement at progressive collapse analysis of reinforced concrete structures is proposed. The energy absorption capacity under the column missing event is used for formulations. The approximate method is simple to utilize, user friendly, yet accurate. For progressive collapse analysis of structures, linear static analysis, nonlinear static analysis, linear dynamic analysis and nonlinear dynamic analysis can be performed. In this paper, the nonlinear static analysis from alternate load path method is used and the reason of initial local collapse has not been considered. In fact, an energy-based method by using load-displacement curve of RC frame and considering the effect of floor slab for the progressive collapse analysis is considered. The accuracy of the proposed method is demonstrated by comparing the results to three experimental and analytical results. Finally, the effects of the spans length, sections dimensions, material properties and the beams reinforcements of column removed spans on substructure behavior is studied, as well.

scholarly journals Progressive collapse scenario in steel structures with irregularity in height

2021 ◽  
Vol 73 (09) ◽  
pp. 893-905
Keyword(s):  
Cross Sections ◽  
Progressive Collapse ◽  
Great Influence ◽  
Nonlinear Dynamic Analysis ◽  
Structural Response ◽  
Steel Structures ◽  
Nonlinear Static Analysis ◽  
Load Path ◽  
Engineering Structures ◽  
Column Removal

Sudden removal of load-bearing elements such as columns in engineering structures, and lack of sufficient capacity to withstand the overload caused by removal of these elements can cause damage and Progressive Collapse (PC) in structures. Therefore, the effect of sudden column removal and structural capacity against PC scenarios in medium and high-rise buildings is investigated in this study. The irregularity in height has a great influence on lateral behaviour of structures and it affects the design of cross-sections. Various sudden column removal scenarios are investigated in this research for steel structures with and without irregularity in height. To assess the effects of sudden column removal, the Alternate load Path Method (APM) and Nonlinear Dynamic Analysis (NDA) are utilized. In addition, a Nonlinear Static Analysis (NSA) is performed to investigate the capacity of structures against the PC phenomenon. Using OpenSees software, 10-, 15- and 20-storey structures with three distinct irregularity types are analysed during four different column removal scenarios. The results are presented in the form of static and dynamic nonlinear curves. The results indicate that making geometric irregularity in height in the sudden column removal scenario can cause the reduction of capacity and growth of the structural response in comparison to the structure with regularity in height. Moreover, the capacity of structures increases and the dynamic response declines by increasing the number of elements in the structures.

Structural reliability of RC frames under sudden column removal scenarios considering static and dynamic methods

2021 ◽  
Author(s):  
Luchuan Ding ◽  
Ruben Van Coile ◽  
Wouter Botte ◽  
Robby Caspeele
Keyword(s):  
Dynamic Analysis ◽  
Structural Reliability ◽  
Progressive Collapse ◽  
Nonlinear Dynamic Analysis ◽  
Load Path ◽  
Dynamic Amplification Factor ◽  
Mean Values ◽  
Column Removal ◽  
Column Removal Scenario ◽  
Failure Probabilities

<p>The alternative load path (ALP) method is widely used to investigate the performance of reinforced concrete (RC) buildings in case of progressive collapse (or disproportional collapse) scenarios. This kind of analysis can be carried out either in a static way or in a dynamic way. In this contribution, these methods are compared by means of nonlinear static and nonlinear dynamic analysis methods. A 5-storey RC frame subjected to two different sudden column removal scenarios is adopted as a case study. The probabilistic analysis considers 12 random variables. On the basis of the stochastic results, a dynamic amplification factor (DAF) is calculated. The mean values of the DAF are 1.114 and 1.102 for the external column removal scenario (Case A) and the internal column removal scenario (Case B), respectively. Compared to the failure probabilities obtained through a static analysis, the failure probabilities for the incremental dynamic analysis results are 184.0% and 180.7% higher for Case A and Case B, respectively.</p>

Improving the robustness of steel frame structures under localised fire conditions

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Riza Suwondo ◽  
Lee Cunningham ◽  
Martin Gillie ◽  
Made Suangga ◽  
Irpan Hidayat
Keyword(s):  
Progressive Collapse ◽  
Steel Frame ◽  
Frame Structures ◽  
Collapse Mechanism ◽  
Building Structures ◽  
Content Type ◽  
Catenary Action ◽  
Lateral Resistance ◽  
Steel Frame Structures ◽  
Fire Conditions

PurposeThe robustness of building structures in a fire has recently drawn wide attention. This study presents the progressive collapse analysis of steel frame building structures under localised fire. The main objective of this study is to propose methods to enhance the structural collapse resistance of such structures in fire.Design/methodology/approachA modelling method was developed and validated against both experimental and analytical studies. Then, a series of robustness analyses were performed to investigate the interaction among the members and the pattern of load distribution within the structures. These analyses show that lateral resistance and load redistribution have a vital role in the robustness of the building. Thus, two approaches have been adopted to enhance the robustness of the focused steel frame during a fire.FindingsIt is found that increased size of floor beams and vertical bracing systems are effective measures in preventing whole structure collapse. The larger beam section is able to prevent catenary action so that the load in the failed columns can safely transfer to the adjacent columns without buckling. On the other hand, the bracing system improves the lateral resistance that can accommodate the lateral force when catenary action occurs in the beam.Originality/valuePrevious studies have focused on the collapse mechanism of steel frame structures. However, the parameters affecting the structural robustness in a fire have not yet been explored. To address this gap, this study adopted numerical modelling to undertake parametric studies to identify effective methods to improve the robustness of such structures under fire conditions.

Analytical Investigation of Progressive Collapse Resistance Mechanism in Steel Moment Frame with Fiber Model

2012 ◽  
Vol 166-169 ◽  
pp. 1848-1853 ◽  
Author(s):  
Chuan Qing Liu ◽  
Zuo Yun Mei
Keyword(s):  
Progressive Collapse ◽  
Resistance Mechanism ◽  
Element Model ◽  
Steel Frame ◽  
Frame Structure ◽  
Load Path ◽  
Bending Resistance ◽  
Column Removal ◽  
Steel Frame Structure ◽  
Middle Column

In order to investigate the resistance mechanism of steel frame structure in progressive collapse, an advanced finite element model(FEM) is presented based on fiber beam-column element. Using this FEM, non-linear static pushdown analysis of a ten-story structure was carried out by the alternate load path method, in the two cases that two different columns are removed respectively. Analytical results show that residual structure has the different resistance mechanism for the different column removal case. In the initial stage, bending resistance mechanism can provide dominate resistance capacity in the structural progressive collapse, after both middle and side columns are removed. However, when the bending resistance is out of work, the catenary action is induced in the case of the middle column removal only, which is not developed after the side column is removed. It can be seen that steel frame structure has higher collapse risk in the case of the side column removal than in the case of the middle column removal.

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