Progressive Collapse Assessment of Multistory Reinforced Concrete Structures Subjected To Seismic Actions

Ahmed Elshaer,Hatem Mostafa,Hamed Salem 대한토목학회 2017 KSCE JOURNAL OF CIVIL ENGINEERING Vol.21 No.1

Progressive collapse is a catastrophic partial or total failure of a structure that mostly occurs when a structure loses a primary component like a column. Some international standards have started to consider progressive collapse resistance in various approaches. In this study, the ‘Unified Facilities Criterion’ guidelines were used in assessing the structure; these guidelines represent one of the codes that discuss progressive collapse using sophisticated approaches. Three-dimensional nonlinear dynamic analyses using the ‘Applied Element Method’ were performed for a structure that lost a column during a seismic action. A parametric study was made to investigate the effect of different parameters on progressive collapse. In this study, a primary structural component was assumed lost during an earthquake. The studied parameters were the location of the removed column in plan, the level of the removed column, the case of loading, and the consideration of the slabs. For the study cases, it was concluded that the buildings designed according to the Egyptian code satisfies the progressive collapse requirements stated by ‘Unified Facilities Criteria’ (UFC) guidelines requirements with a safety factor of 1.97. Also, it was found that losing a column during a seismic action is more critical for progressive collapse than under gravity load. Finally, this study elaborated the importance of considering the slab in progressive collapse analysis of multistory buildings in order to include the significant catenary action developed by the slabs.

On the progressive collapse resistant optimal seismic design of steel frames

Amin Rafiee,Ali Hadidi,Ramin Jasour 국제구조공학회 2016 Structural Engineering and Mechanics, An Int'l Jou Vol.60 No.5

Design of safe structures with resistance to progressive collapse is of paramount importance in structural engineering. In this paper, an efficient optimization technique is used for optimal design of steel moment frames subjected to progressive collapse. Seismic design specifications of AISC-LRFD code together with progressive collapse provisions of UFC are considered as the optimization constraints. Linear static, nonlinear static and nonlinear dynamic analysis procedures of alternate path method of UFC are considered in design process. Three design examples are solved and the results are discussed. Results show that frames, which are designed solely considering the AISC-LRFD limitations, cannot resist progressive collapse, in terms of UFC requirements. Moreover, although the linear static analysis procedure needs the least computational cost with compared to the other two procedures, is the most conservative one and results in heaviest frame designs against progressive collapse. By comparing the results of this work with those reported in literature, it is also shown that the optimization technique used in this paper significantly reduces the required computational effort for design. In addition, the effect of the use of connections with high plastic rotational capacity is investigated, whose results show that lighter designs with resistance to progressive collapse can be obtained by using Side Plate connections in steel frames.

A Proposed Procedure for Progressive Collapse Analysis of Common Steel Building Structures to Blast Loading

Meysam Bagheri Pourasil,Yaghoub Mohammadi,Amin Gholizad 대한토목학회 2017 KSCE JOURNAL OF CIVIL ENGINEERING Vol.21 No.6

There is rising concern among researchers regarding the suitability of structural design for abnormal load resistance. Abnormal loading generated by a blast or impact can cause local damage to a structure that could affect the entire structural system. Structures must be designed to prevent such disproportional consequences. Research has focused on progressive collapse analysis of buildings, most of which are based on the alternative path method and the sudden removal of one or several columns. In this procedure, failure of elements adjoining to the removed columns under blast conditions are ignored, which can lead to an incorrect prediction of progressive collapse. The present study developed a procedure for progressive collapse analysis of common steel building structures subject to blast loading. A 3D numerical model for direct simulation of blast loading is proposed to study the real behavior of a 7-story building under blast loading. A blast load equivalent to 1 t of TNT was simulated at a distance of 4 m from the corner of the structure to assess the direct effect on the structure. The pressure of this blast at 4 levels of loading was applied to adjacent structural members and the structural response was examined and the exciting forces in the adjacent structural members of the blast site were compared. The results indicate that the potential for progressive collapse when assuming blast loading as the initial cause of failure will differ from results of common methods used for evaluation of progressive collapse and in methods that ignore the initial reason for progressive collapse.

Comparative Analysis of Code-Based Dynamic Column Removal and Impact-Induced Progressive Collapse in Steel Moment-Resisting Frames

Iman S. Janfada,Mohammad Reza Sheidaii,Foad Kiakojouri 한국강구조학회 2023 International Journal of Steel Structures Vol.23 No.6

Civil structures are subjected to accidental or intentional impacts, which can lead to an initial failure, and subsequently to a tragic progressive collapse. While progressive collapse studies have seen significant growth, most of the current research focuses on threat-independent approaches, neglecting the explicit consideration of impact effects on the building’s behavior. In this study, we investigate impact-induced progressive collapse, exploring various scenarios with different mass and velocity parameters. By doing so, this study aims to highlight the importance of explicitly accounting for impacts in progressive collapse analyses and provide possible solutions for safer structural design. For comparison, code-based dynamic column removal analyses are also performed and the results are compared and contrasted. Based on the obtained results, location of the damage and height of the building have important influence on the progressive collapse response in both threat-independent and threat-dependent approaches. Velocity plays a significant and critical role compared to mass in increasing the kinetic energy applied to the building, and the vertical vibration in the node on top of the impacted column. With the lower impactor velocities, the threat-independent method can be used safely, however, for the higher velocities the progressive collapse potential is much higher in threat-dependent approach compared with code-based dynamic column removal.

하중 재분배에 의한 RC 구조물의 연쇄붕괴 저항성능 평가

박훈,석철기 한국방재학회 2013 한국방재학회논문집 Vol.13 No.6

Progressive collapse indicates the partial or total collapse of structures caused by the local damage of structural members arisingfrom an abnormal load. To induce ideal collapse behavior, the progressive collapse is applied to most explosive demolitiondesign for structures. To apply this progressive collapse phenomenon to the explosive demolition of structures, studies on progressivecollapse resisting capacity depending on load redistribution are required. In this study, the progressive collapse analysis ofa 10-story RC frame structure was performed by the applied element method for various 1st column removal cases. For each case,the progressive collapse resisting capacity of columns, girder, and slabs was evaluated by the increase rates of the vertical internalforce in columns, the normal stress of reinforcing bars in girder, and the tensile stress of slab, respectively. 비정상하중에 의해 발생하는 구조부재의 국부손상이 구조물의 국부파괴 또는 전체파괴로 이어지는 연쇄붕괴는 이상적인 붕괴거동을 유도하기 위해 대부분의 구조물 발파해체 설계에 적용된다. 이러한 연쇄붕괴 현상을 구조물 발파해체에 적용하기 위해서는 하중의 재분배에 따른 연쇄붕괴 저항성능에 대한 연구가 요구된다. 본 연구에서는 응용요소법을 이용하여 10층 철근콘크리트 구조물의 연쇄붕괴 해석을 수행하였다. 구조부재인 기둥 요소의 제거 수와 제거 위치를 달라하여 하중의 재분배에 따른 기둥, 보, 슬래브에 대한 연쇄붕괴 저항성능을 평가하였다. 기둥의 수직내력 증가율은 하중의 재분배 경로수와 재분배 면적비에영향을 받으며, 거더 하부근과 슬래브의 인장응력이 현수작용을 증대시키고, 연쇄붕괴에 저항하고 있음을 알 수 있다.

Dynamic analysis method for the progressive collapse of long-span spatial grid structures

Li-Min Tian,Jian-peng Wei,Ji-Ping Hao,Xian-tie Wang 국제구조공학회 2017 Steel and Composite Structures, An International J Vol.23 No.4

In the past, the progressive collapse resulting from local failures during accidents has caused many tragedies and loss of life. Although long-span spatial grid structures are characterised by a high degree of static indeterminacy, the sudden failure of key members may lead to a catastrophic progressive collapse. For this reason, it is especially necessary to research the progressive collapse resistance capacity of long-span spatial grid structures. This paper presents an evaluation method of important members and a novel dynamic analysis method for simulating the progressive collapse of long-span spatial grid structures. Engineering cases were analysed to validate these proposed method. These proposed methods were eventually implemented in the progressive collapse analysis of the main stadium for the Universiade Sports Center. The roof of the structure was concluded to have good resistance against progressive collapse. The novel methods provide results close to practice and are especially suitable for the progressive collapse analysis of long-span spatial grid structures.

Progressive Collapse Resistance of Bolted Extended End-Plate Moment Connections

Samad Barmaki,Mohammad R. Sheidaii,Omid Azizpour 한국강구조학회 2020 International Journal of Steel Structures Vol.20 No.4

When a progressive collapse occurs due to sudden column removal, the moment connections must have adequate strength and be able to bridge over the damaged element. The present study comprehensively investigates the behavior of eight diff erent types of extended end-plate beam-to-column connections against progressive collapse. The proper fi nite element models have been extended to assess the behavior of these bolted connections under a sudden column removal scenario. Specimens were checked by nonlinear analysis method. The fracture modes, Von-Mises stresses, vertical load–displacement and load factor–displacement curves, load transferal mechanisms, and other analytical results comparative were reported in detail and discussed for various investigated beam-to-column connections. The analysis results revealed that the overall failure of the samples occurred in the connection region under the catenary action mode at large displacements. Also, the results were verifi ed with available experimental data. Among all investigated connections, the highest stresses could be applied to the sixteen-bolt stiff ened connection, and this sample had the most excellent behavior. In the design of buildings exposed to unusual loads due to progressive collapse, the signifi cant axial force created in the connections should be considered in the design stages of these elements. Also, it is recommended that at least three rows of bolts are embedded in the bottom area of end-plate connections when the structure is at the risk of progressive collapse.

Progressive collapse of reinforced concrete structures

Yagob, O.,Galal, K.,Naumoski, N. Techno-Press 2009 Structural Engineering and Mechanics, An Int'l Jou Vol.32 No.6

In the past few decades, effects of natural hazards, such as earthquakes and wind, on existing structures have attracted the attention of researchers and designers. More recently, however, the phenomenon of progressive collapse is becoming more recognized in the field of structural engineering. In practice, the phenomenon can result from a number of abnormal loading events, such as bomb explosions, car bombs, accidental fires, accidental blast loadings, natural hazards, faulty design and construction practices, and premeditated terrorist acts. Progressive collapse can result not only in disproportionate structural failure, but also disproportionate loss of life and injuries. This paper provides an up-to-date comprehensive review of this phenomenon and its momentousness in structural engineering communities. The literature reveals that although the phenomenon of progressive collapse of buildings is receiving considerable attention in the professional engineering community, more research work is still needed in this field to develop a new methodology for efficient and inexpensive design to better protect buildings against progressive collapse.

Performance of Low-yield Strength Plates in Beam-column Connections against Progressive Collapse

Ahmad Karimian,Arastoo Armaghani,Alaeddin Behravesh 대한토목학회 2019 KSCE Journal of Civil Engineering Vol.23 No.1

In many studies about progressive collapse in steel moment frames, the effect of connections in all of structural frames has not been investigated. This is while the connections can have a significant impact on structure behavior against abnormal loads. This study highlights the effect of mechanical and geometric properties of beam-column connections in steel moment frames against progressive collapse. For this purpose, variable parameters include beam-column connection type (Welded Flange Plate connection or WFP and Welded Unreinforced Flange-Welded web connection or WUF-W), mechanical properties of beam-column connection (St37 building steel and low-yield strength plates) and the column removal location in different stories (without removing column and removing column on the ground, first and second floors). Three-storey steel frames which are designed to withstand earthquakes are examined. Finite element ABAQUS software is used for simulation. Moreover, the alternative load path method in which the structure response is examined against the column removal is used to evaluate steel frames response against progressive collapse. The results show that the use of low-yield strength steel plates depending on connection type can be efficient in improving the behavior of steel moment frames against progressive collapse.

Assessment of Progressive Collapse Behaviour of Moment Frames Strengthened with Knee Elements

Peiman Rezazadeh,Mohammad R. Sheidaii2,Alireza Salmasi 한국강구조학회 2019 International Journal of Steel Structures Vol.19 No.2

Knee element can be used in junction of beam and column elements for strengthening steel moment frames against progressive collapse. Two diff erent types of knee elements, namely strong and weak knee elements have been used to strengthen the frames. Strong knee element has been designed in a way that it prevents the occurrence of plastic hinge on knee element before beam element. But in weak knee elements, formation of plastic hinge on knee element will be prior to formation of the plastic hinge on the beam element. The nonlinear static alternate path analysis in accordance with the UFC guideline has been used to determine the resistance of structures against progressive collapse. The results indicate the priority of strong knee elements compared to weak knee elements in strengthening the structure against progressive collapse. Installing strong knee element reduces the eff ective length of beams and columns and changes the direction of fl ow of forces from the beam–column connection to out of the knees area and changes the position for the formation of plastic hinges. Eventually, the installation of strong knee elements will increase stiff ness and structural strength and result in better behaviour against progressive collapse.