Progressive Collapse Of Building Structures Research Articles

Experimental studies on the progressive collapse of building structures: A review and discussion on dynamic column removal techniques

Dynamic progressive collapse tests are becoming more and more popular in recent years since this approach captures the real structural behavior more robustly, and progressive collapse response more accurately. The results of dynamic tests are of great importance for defining computational models and improving current codes and guidelines. Even for static tests and simulations, the dynamic effects should be indirectly considered, namely by including the dynamic amplification factors. The adopted dynamic column removal approach is the most important and challenging aspect of the dynamic progressive collapse tests. While several methods for dynamic column removal have already been suggested and implemented, a comprehensive discussion of the techniques is missing. In this regard, a comprehensive review of the available literature is first presented. Current experimental techniques for dynamic column removal are categorized into three main groups, i.e., quick-release device, dummy column, and explosion technique, and the underlying concepts and applied methodologies are compared and contrasted. Finally, future needs are highlighted and possible improvements for the current methodologies are also discussed.

A substructure based method for damage assessment of RC frame structures under close-in explosion

Few studies are available in the literature on damage assessment of frame structures under blast loads although local damage of the structural components and even progressive collapse of building structures have been observed in terrorist or accidental explosions. In this paper, considering the initial damage of adjacent structural components under blast loading, a substructure based method for damage assessment of RC frame structures is proposed, including the proposal of the damage criterion, the principles for substructures selection and the calculation of the boundary conditions of the substructures. The accuracy and reliability of the proposed method are verified by comparing the results for damage assessment of a typical 5-story frame structure under different blast scenarios with the conventional method and the proposed method. The results indicated that the proposed method could rapidly and accurately predict the damage levels of the RC frame structure under a given blast load, especially when the building structures are damaged under close-in explosion.

Experimental assessment of the residual capacity of axially loaded blast-damaged square RC columns

The aftermath of the Oklahoma City Bombing and the events of September 11, 2001 in the United States led to intense research into the response of infrastructure to explosion effects and the attendant risk of progressive collapse of building structures. The research has not addressed the residual capacity of blast-damaged columns. The challenge to structural engineers is determining the residual capacity of blast-damaged columns and deciding which should be demolished and which can be repaired cost-effectively. This paper presents the results of an experimental program designed to investigate the residual capacity of blast-damaged columns in the laboratory.The blast-damaged columns, from an earlier field test program, were first subjected to the design axial service load of 1000 kN. Columns capable of resisting the service load were subjected to additional lateral loading to determine their residual flexural capacity. The test results show that columns with reduced tie spacing exhibited higher post-blast residual capacity from the explosion at the same scaled distance. Also, a high axial load ratio was observed to adversely affect the flexural load capacity of the reinforced concrete columns in a numerical parametric analysis done using the finite element program LS-DYNA.

DYNAMIC EFFECTS BY THE STRUCTURAL DAMAGE OF THE BUILDING STRUCTURE

Purpose. To review the standards and the scientific literature on emergency load calculations that are linked with stability to progressive collapse of building structures and dynamic influence of localized structural component damage (failure) on the building structure. To study the dynamic influence on the building structure of its localized structural component damage by laboratory experiment and numerical simulation. Methodology. To reach the goal the existing standards and the scientific literature of different countries on calculations and design of resistant to progressive collapse buildings and structures were reviewed. The laboratory bench was created. Experimental and numerical studies were conducted by modelling dynamic behaviour of the building structure. The laboratory bench was statically indeterminate system in order to localized structural component damage (failure) did not lead to the hole structure destruction but only to its qualitative reconfiguration. Findings. During the laboratory experiment the vibrational accelerations and displacements for characteristic point of structure were registered. By processing vibrational diagrams, the values of the frequencies and the laboratory bench free vibrations logarithmic decrements were received, as well as the value of the dynamic increase factor by different load levels and different failure types. Experimental results were checked by numerical simulation. Originality. The studies allow to evaluate dynamic effect of localized structural component damage two types. It was also discovered that the values of dynamic displacements and accelerations may be differentby several times by the comparable values of the dynamic increase factors of different failure types. Practical value. The results suggest that in the case of total structural component failure the value of dynamic increase factor (stresses and accelerations) is more than that in the case of structural component damages while retainingpartial functionality. In such a case when carrying out practical engineering calculations it would be sufficient to consider the total structural component failure while the possibility of partial damages would be as reserve of power.

Parametric analysis and simplified approach for steel-framed subassemblies with reverse channel connection under falling-debris impact

Up to now, most studies corresponding to building structures against progressive collapse are based on the column-removal scenario. However, other cases, i.e., falling-debris impact scenario, which may cause progressive collapse of building structures were limitedly studied. This paper presents numerical simulations and a simplified approach of steel-framed subassemblies with Reverse Channel connection with Extended End Plate (RC-EEP) under the falling-debris impact scenario. The numerical results demonstrate the ductility, load-carrying capacity, and energy-absorption capacity of the steel-framed subassemblies with different Span-to-Depth Ratio under various impacted locations. All specimens showed the same global deformation profile and same load-resistance mechanism under the impact load on the same locations. Under mid-span-impact scenario, axial elongation of connection primarily affected the ductility. Both catenary action and flexural action affected the load-carrying capacity. Failure displacement, maximum load-carrying capacity and energy-absorption capacity all decreased with the increase of the Span-to-Depth ratio. Under beam-end-impact scenario, both the ductility and the load-carrying capacity were primarily controlled by the shear deformation and shear strength of the connection close to the impacted location. The increase of the Span-to-Depth ratio had little effect on failure displacement while slightly reduced the maximum load-carrying capacity and energy absorption capacity. Smaller Span-to-Depth Ratio was recommended in the impact-resisting design for impact load on both impact locations. A simplified approach was also developed to predict the behaviour of the steel frame subassemblies up to total failure. The validation study indicated that the proposed models can represent the key responses of steel-framed subassemblies with different Span-to-Depth Ratio subjected to impact load on various locations, including the flexural action at pure bending stage, the development of flexural action and catenary action at the tension-bending stage, and the failure stage. The accuracy of the proposed approach was validated against the experimental tests and numerical simulations, in the aspects of internal force-displacement relationships, load-carrying capacity-displacement relationships, and energy absorption-displacement relationships. The proposed approach provided an accurate and efficient way to predict the impact resistance of specimens with various Span-to-Depth Ratios under both of the mid-span impact and the beam-end impact scenarios.

Finite-Element Modeling of Progressive Failure for Floor-to-Floor Assembly in the Precast Cross-Wall Structures

AbstractThe progressive collapse of building structures typically occurs when an abnormal loading condition causes a sudden loss in the structural capacity of one or more critical members, which le...

Robustness assessment of planar steel frames caused by failure of a side column under localized fire

SummaryProgressive collapse of a building structure under fire is a disaster that may cause heavy casualties and serious economic loss. However, there is a lack of codified method to assess fire‐induced progressive collapse of building structures. A global–local analysis method (GLAM) has recently been proposed by the authors and their colleagues to assess progressive collapse of steel buildings under localized fire, and its application on fire scenarios that causes one inner column to fail has been verified. This paper extends the application of GLAM to fire scenarios that causes a side column to fail in a planar steel frame. The predictions of the GLAM were validated against the results obtained from nonlinear dynamic analysis of the whole frame model. Besides, effects of location of the heated column at different storeys and load level of the frame were also studied. The results show that GLAM gives the same collapse predictions to the case studies with detailed nonlinear dynamic analysis. The differences between the critical load obtained from GLAM and that provided by the nonlinear dynamic analysis is within 7%. Therefore, GLAM has good applicability on robustness assessment of planar steel frames caused by failure of a side column under localized fire.

Substantiation of the method for the calculated evaluation of the resistance of buildings to progressing destruction due to the fire

During the fire safety analysis of building structures besides evaluation of their fire resistance, the limits of spreading of fire, fire hazards parameters and other fire and technical characteristics, the probability of progressive collapse of building structures due to their individual elements destroying should be considered. Considering the uniqueness, massiveness and cost of reinforced concrete and other buildings structures, their natural tests are ineffective, since they contemplate manufacturing two samples of structures in compliance with all technologies. In the conditions of progressive collapse of structures, socio-economic losses are becoming the largest scale. An assessment of the possibility of progressive collapse is possible only with the use of a computational approach. This situation necessitates a calculation to assess the progressive destruction possibility of buildings and structures, which is fixed in the building codes of many countries. The article proposes a calculation method for assessing the possibility of progressive collapse, which is based on the assumption that one or more compressed elements are damaged and must be removed from the system, which ensures its rigidity and geometric constancy. The basic principle of the method is the hypothesis of the formation of a line of plastic hinges in the floor slab, which can be explained using a Bezier curve. The assessment of the possibility of progressive collapse is carried out by determination the energy criterion on the basis of comparing works of internal and external forces on possible displacements of the system, which under such conditions is geometrically variable. The proposed method is productive and economical in comparison with existing methods that involve complex mathematical models and software packages. These methods are based on standards harmonized with the relevant methodological and regulatory framework of the united Europe, and also consistent with the research results of domestic and foreign authors, which are tested, discussed and recognized by the scientific community and are included in the main base of literary references and are cited by experts in this industry.

Research progress on progressive collapse resistant analysis and design of building structures under blast loading

Progressive collapse is defined as the spread of an initial local failure from a key element to adjacent elements, eventually resulting in the collapse of the whole structure or a disproportionately large part of it. As an abnormal dynamic load, blast load has the characteristic of rapid propagation, high peak value and short duration. And it is also one of the main reasons that might cause the progressive collapse of building structures. Based on the existing research achievements on the progressive collapse of building structures, in this paper the classification method for structural progressive collapse analysis is put forward. Then the current methods for progressive collapse analysis are further divided into two categories, i.e., the method for evaluation of structural progressive collapse resistance and the method for whole process analysis of structural progressive collapse. Recent progress on the evaluation of structural progressive collapse resistance and the method for whole process analysis of structural progressive collapse are presented from literatures. Finally, the conceptual design method, structural detailing and the procedure for progressive collapse resistant design of building structures against blast loading are put forward.

Exploring numerical approaches for pre-test progressive collapse assessment of RC frame structures

Finite element (FE) codes can be used for the assessment of progressive collapse of building structures. However, the effectiveness and accuracy of such simulations is highly dependent on the accuracy of modeling the structural systems and their connections. A four-story full-scale reinforced concrete structural frame was selected for the present study. The structure was tested by other investigators for assessing its progressive collapse behavior, and the results were published after this study had been completed. A predominantly continuum based FE model was developed in this study for the structural system that addressed the effect of beams and slab on the load resistance of the connections. A load resistance function of the connections was derived, as a basis for a fast-running FE model, to simulate the behavior of such connections. This simplified FE approach was validated by simulating connection details that were tested by other investigators, and it produced very similar results with significant time saving, as compared to full 3D FE simulations, for the same connection test specimens. It enabled one to obtain reasonable estimates of the load-rotation function of the interior connection at a much-reduced computational time. Therefore, the simplified approach was used for the progressive collapse assessment of the tested structural system, and the obtained results were compared with test data.

Earthquake-Induced Domino-Type Progressive Collapse in Regular, Semiregular, and Irregular Bridges

Progressive collapse is a persistent spread and enlargement of initial local failure of structures characterized by inconsistency between the initial failure and its resulting extensive collapse. Although, great contributions have been made towards the progressive collapse of building structures, comparably small attention has been paid to bridge structures. In this study, the procedure of progressive collapse of bridges with concrete prestressed voided slab under earthquakes and effects of other parameters on propagation of collapse of regular, semiregular, and irregular bridges are investigated. At first, a bridge specimen, which its shake table test results were provided by previous researchers, was modeled and verified using the applied element method. Then, the progressive collapse of the box girder bridge was investigated. In the next step, progressive collapse process of the same bridge with posttensioned voided slab under earthquakes was studied using nonlinear time history analysis. Irregularities of the piers were analyzed parametrically. The results show that domino-type progressive collapse happens in bridges with voided slab after the initial failure of the deck at the seating of bridge abutment. Also, it is concluded that, type of the deck, height of the piers, and ground slope have a great effect on the progressive collapse procedure of both regular and irregular bridges with voided slab deck.

RESEARCH AND STANDARDS ON PROGRESSIVE COLLAPSE OF STEEL BUILDING UNDER ABNORMAL LOADS

The phenomenon of progressive collapse of building structures is an important focus in construction design. After the chain destruction of the Ronan Point in 1968, a range of studies were directed on the causes establishment of the appearance of progressive collapse and methods of protection against them. Trigger accident events contributed to damage have a different nature and are referred to as abnormal loading. The performance of the building collapse is also in depending on the construction materials and the design schemes. Many scientists from different countries dealt with the challenges of progressive collapse. Their research has found application in modern building codes and regulations. This article provides a brief review of current analysis methods for progressive collapse of steel structures under abnormal loads, as well as Russian and foreign standards related to this academic field.

Analytical model for predicting membrane actions in RC beam-slab structures subjected to penultimate-internal column loss scenarios

The potential for progressive collapse of RC buildings can be estimated by column loss scenarios. The loss of either internal or external penultimate columns is among the most critical scenarios since the beam-slab substructures associated with the removed column becomes laterally unrestrained with two discontinuous edges. At large deformations, membrane behaviour of the associated slabs, consisting of a compressive ring of concrete around its perimeter and tensile membrane action in the central region, represents an important line of defence against progressive collapse. The reserve capacity can be used to sustain amplified gravity loads and to mitigate the progressive collapse of building structures. In this paper, based on experimental observation of 1/4 scaled tests together with investigation of previous research works, an analytical model is proposed to predict the load-carrying capacity of beam-slab structures at large deformations. Comparison with the test results shows that the analytical model gives a good estimation of the overall load-carrying capacity of the RC slabs by membrane actions.
 Article history: Received 15 March 2018, Revised 28 March 2018, Accepted 27 April 2018

Effect of floor joint design on catenary actions of precast floor slab system

To prevent progressive collapse of building structures, the establishment of the catenary action mechanism of beams or slabs is crucial so that adequate post-collapse resistance can be attained. It is believed that the joint design of precast floor system, e.g. the tie design, plays a key role in facilitating such a mechanism. An experimental study has been undertaken to investigate the catenary behaviour of the precast concrete slab system following the removal of the intermediate wall supports. To this end, five large-scale concrete floor assembly tests have been devised and carried out. Each test consisted of two standard hollow core floor slab units with various tie arrangements at the joints, which resembled a single storey floor structure supported by cross walls. The floor joint ties were placed on the pre-existing keyways where the grout was cast after the test assemblies were set up. The grout strength was specified to be 20–30MPa and 10 or 12mm tie bars were used with an embedment length ranging from 250mm to 350mm. Test results indicated that specimens experiencing bar fracture failure patterns collapsed prior to the formation of the catenary action, but those specimens with the pull-out failure pattern showed clear evidence of catenary behaviour. Furthermore, the difference in the post-collapse behaviour and the failure patterns indicated the characteristics of the catenary action. Test results reveal that for the ties designed with inadequate embedment length, the slip and the resulting large deflection will effectively trigger the catenary action. However, the full bond will limit the development deflection and lead to the fracture of tie bars before the catenary action is trigged.

Progressive Collapse of a Cable Stayed Bridge

Progressive collapse is a persistent spread and enlargement of initial local failure of structures characterized by a discrepancy between the initial failure and its resulting extensive collapse. Although great efforts have been contributed to the progressive collapse of building structures, comparably small attention has been paid to the bridge structures, especially the cable-stayed bridges. This study demonstrates modelling and analysis of a typical cable stayed bridge through a nonlinear dynamic procedure. Furthermore, the response of the structural model is discussed for multiple types of critical cable loss cases. The results indicated a decrease in the possibility of failure progression of the cable stayed model when the location of the failed cables was closer to the pylon. A definite progressive collapse pattern was also identified along this procedure.

Nonlinear Progressive Collapse Analysis Including Distributed Plasticity

This paper demonstrates the effect of incorporating distributed plasticity in nonlinear analytical models used to assess the potential for progressive collapse of steel framed regular building structures. Emphasis on this paper is on the deformation response under the notionally removed column, in a typical Alternate Path (AP) method. The AP method employed in this paper is based on the provisions of the Unified Facilities Criteria – Design of Buildings to Resist Progressive Collapse , developed and updated by the U.S. Department of Defense [1]. The AP method is often used for to assess the potential for progressive collapse of building structures that fall under Occupancy Category III or IV. A case study steel building is used to examine the effect of incorporating distributed plasticity, where moment frames were used on perimeter as well as the interior of the three dimensional structural system. It is concluded that the use of moment resisting frames within the structural system will enhance resistance to progressive collapse through ductile deformation response and that it is conserative to ignore the effects of distributed plasticity in determining peak displacement response under the notionally removed column.

Dynamic analyses of bolted-angle steel joints against progressive collapse based on component-based model

Some design methods have been proposed to prevent progressive collapse of building structures. Alternate Path (AP) Method is the most effective and popular one among them. Based on component-based joint models, this paper takes AP Method to study the dynamic performance of two-dimensional (2D) bolted-angle steel joints under a sudden column removal scenario. The comparison between the quasi-static and dynamic responses of the component-based models simulated by finite element software and the experimental test results shows that the component-based models are reliable. After that, based on the validated component-based models, parametric study was conducted in order to study the dynamic responses of bolted-angle steel joints subjected to different levels of sudden gravity loads. These 2D steel joints employ two types of beam–column connections, including web cleat connections and top and seat with web angle connections. Dynamic increased factors (DIFs) are obtained by comparing the acquired dynamic responses with the corresponding nonlinear static responses of the bolted-angle steel joints. Finally, DIFs calculated in this study are compared with the regulations of Department of Defense (DoD) in United States and a simplified energy balance method. As a conclusion, it is found that the numerical results in this study are in good agreement with the energy balance method.

Calculation of load increase factors for assessment of progressive collapse potential in framed steel structures

Progressive collapse of building structures is a relatively rare event. However, the consequences of progressive collapse may be catastrophic in terms of injuries and loss of lives. In addition, in many parts of the world including the United States of America, Europe, Asia, and recently, United Arab Emirates, there is a trend to build taller and more structurally complicated buildings with adventurous load paths. Therefore, structural design that takes into account the potential for progressive collapse is becoming critical. This paper outlines and discusses the process of estimating the load increase factor (LIF) needed for progressive collapse resistant design of steel building structures that takes into account the effects of component ductility on structural response following the initiation of collapse. LIF are used to account for the dynamic effects of column/wall removal when the designer opts for linear or nonlinear static analysis to assess the potential for progressive collapse. The approach recognizes the difference in response associated with deformation-controlled compared to force-controlled response quantities and structural elements. Emphasis in this paper is on the Alternate Path (AP) approach which is the most commonly used approaches for progressive collapse resistant design of building structure that fall under Occupancy Category II.

Fire induced progressive collapse of steel building structures: A review of the mechanisms

In this paper, a literature review of the mechanisms involved in fire induced progressive collapse of steel building structures are presented. Researchers have been investigating progressive collapse of building structures for some time. With the changing political climate around the world highlighted by the events of September 11th, 2001, researchers have begun to further study the mechanisms of fire induced structural collapse of steel building structures. Furthermore, with the use of performance based building codes throughout the world, engineers can now investigate the use of alternative structural fire protection strategies. This summary provides a brief overview of conventional fire protection strategies for steel buildings and then describes current work done by researchers in the area of the mechanisms involved in fire induced progressive collapse of steel building structures. A summary of two possible design methodologies for resistance of fire-induced progressive collapse are presented.

A Review on Progressive Collapse of Building Structures

Progressive collapse of building structures is generally triggered by a local failure due to accidental actions, followed by subsequent chain effect of the structures which may result in wide range failure or even collapse of the entire buildings. Since the “911” event, progressive collapse of building structures has been widely concerned by engineers and researchers. This paper assesses the current researches on this issue from experimental study, numerical simulation and theoretical analysis. Given the limitation of costs and difficulties of experimental tests, the experimental studies investigate the collapse mechanism, such as development of stress/strain and damage/failure of materials, mainly via the scaled down specimens of structural components and substructures. On the other hand, the collapse behavior of entire building structures is analyzed via the numerical methods, such as the finite element method and the discrete element method. Further, the collapse resistance demand and the robustness assessment for building structures are theoretically studied in depth in which the simplified theoretical models of the collapse-resisting demand and the collapse risk assessment are proposed respectively. At last, the design method to prevent progressive collapse for building structures is also discussed.