Progressive Collapse Analysis Research Articles

Scientific Support of Construction of Unique Buildings and Structures and Facilities of Increased Danger

A range of works on scientific support for the construction of unique buildings and the structures and facilities of increased danger, such as airport facilities, long-span and high-rise buildings is being implemented at the department “Computer Aided Design in Civil Engineering” of Ural Federal University. The scope of work includes: numerical simulation of wind and snow loads, analysis of progressive collapse and seismic impacts, verification of design solutions. The results of wind, snow loads and progressive collapse of airport buildings in the cities of Orenburg, Rostov-on-Don and Perm are considered in the article.

Flexural, Compressive Arch, and Catenary Mechanisms in Pseudostatic Progressive Collapse Analysis

Progressive collapse has drawn significant attention from researchers because of its potential to inflict severe damage and casualty. Much research has focused on simulation techniques for collapse, but comparatively little has examined the interactions among the three main mechanisms of flexural, compressive arching, and catenary actions by way of simplified methodologies. This paper introduces a theoretical method to calculate the collapse resistance of reinforced concrete frame structures in static progressive collapse analysis. The lumped-damaged plasticity method was used to simulate flexural analysis, and compressive arch and catenary actions were calculated using geometry analogies assuming rigid body rotation after initiation of plastic hinging. The method was validated by comparing the simulation results with experimental data, wherein reinforced concrete beam-column assemblies subjected to column removal were tested pseudostatically. The flexural and arching actions were well predicted by the proposed methodology, though the assumed failure mechanism at the end of the simulated catenary action was conservative compared to the experimental results. Overall, the developed method integrating flexural, compressive arch, and catenary actions during collapse was found to be a reliable tool for quick estimation of collapse resistance in static progressive collapse resistance.

APPLICATION OF AEM IN PROGRESSIVE COLLAPSE DYNAMICS ANALYSIS OF R.C. STRUCTURES

The Finite Element Method (FEM) and the other numerical strategies are viably actualized in linear and non-linear analysis of structures. Recently, a new displacement based on Applied Element Method (AEM) has been developed. It is applicable for static and dynamic for both linear and non-linear analysis of framed and continuum structures. In AEM, the structural member is partitioned into virtual elements connected through normal and shear springs representing stresses and strains of certain portion of structure. FEM assumes the material as continuous and can indicate highly stressed region of structure, however it is difficult to model separation of element unless crack location is known. The main advantage of AEM is that it can track the structural collapse behavior going through all phases of the application of loads.In the current research, the application of AEM is illustrated through a non-linear dynamic analysis. Progressive collapse simulation is conducted using Extreme Loading for Structures software (ELS), which follows the AEM. The experimental and analytical works carried by Park et al. [17 and 28] for 1/5 scaled 3 and 5 stories reinforced concrete structures are used for verification. Good matching between the experimental and numerical results has been obtained using ELS. Therefore, it can be confirmed that ELS is capable in simulating the structures’ behavior up to collapse.Furthermore, a study has been made to investigate the effect of considering the floor slabs on progressive collapse. The results show that considering slab in progressive collapse analysis of multistory buildings is important as neglecting the slabs’ contribution leads to incorrect simulation and uneconomic design.

Dynamic analysis of concrete-filled steel tube composite frame against progressive collapse based on benchmark model

To provide a unified assessment standard in both seismic analysis and progressive collapse analysis, a benchmark model with joint substructure for concrete-filled steel tube composite frame is developed and studied by alternative path method. The effects of failure period on dynamic response of the model and two types of dynamic increased factor are analyzed. Demand–capacity ratio is used to evaluate the progressive collapse behavior of the model. The results show that beyond 0.5 time of natural vibration period, the failure period has almost no effect on the dynamic response of the model. The peak moment–nominal moment capacity ratio of the beams connected to the removed column indicates that the closer the column gets to side column with pin connections, the more potential it has to trigger collapse. The bending stiffness of beam has little effect on the dynamic response of the model when it is greater than the doubled value. Displacement-based dynamic increased factor in linear static analysis is almost identical to load-based dynamic increased factor in linear static analysis in each case of column removal. Compared with the value of load-based dynamic increased factor, the value of displacement-based dynamic increased factor in nonlinear analysis is closer to the recommended value of 2.0 in GSA.

Progressive Collapse Analysis of Reinforced Concrete Structures: A Simplified Procedure

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.

Progressive Collapse Analysis of Reinforced Concrete Structures: A Simplified Procedure

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.

Robustness analysis of steel structures with various lateral load resisting systems under the seismic progressive collapse

Abstract Robustness is called to non-sensitivity of a structure to local damage. In the literature of Civil Engineering, the sensitivity of structures to the local damage which can cause a progressive collapse is called Robustness Index. After 9/11, progressive collapse drew the attention of researchers and since that time, increasing the Robustness Index in a structure has been considered as one of the factors in strengthening the structure against progressive collapse. The aim of this study is assessing the Robustness Indices of steel structures having various lateral load resisting systems. So, 8-story, 4-story and 15-story structures with Moment Frames, Concentrically Braced Frames and Eccentrically Braced Frames were modeled and assessed under Robustness analysis. For a progressive collapse analysis, the Alternative Load Path method was used and after emerging local damage, the potential of progressive collapse was assessed using the Robustness Index. First, Robustness analysis was carried out on the basis of Robustness Index assessment using Stiffness and Base Shear methods. Subsequently, it continued by introducing a simple method based on Energy. The results show that despite their simplicity, the methods which are based on Stiffness and the Base Shear, have lots of disadvantages. But, the Energy method has better capabilities for understanding the behavior of structure under seismic loads in progressive collapse scenario. Furthermore, structures which have bracing had a better reaction in progressive collapse scenario.

Prediction of the Bolt Fracture in Shear Using Finite Element Method

This study was aimed to propose appropriate failure criteria for bolt fracture prediction in shear when threads are excluded from the shear plane. In this regard, the finite element methods for such prediction were divided into two main categories and for each category the available methods were discussed. Then, using finite element modeling and available experimental results of previous researchers, three methods here referred to as MTD1, MTD2 and MTD3 were proposed. MTD1 and MTD2 were based on the monitoring of the level of stress and strain at the critical elements of the bolt shank, while MTD3 was based on the extended finite element method and consisted of two main steps including defining crack initiation and crack evolution. Analytical results indicated that MTD1 and MTD3 were reasonably acceptable for prediction of the bolt fracture in shear with negligible amount of error. Method MTD1 is a suitable method when a progressive collapse analysis is not of interest and only the capacity of the system at the onset of the first bolt fracture is required. However, MTD3 can be used in a progressive collapse analysis where the amount of reduction in a system strength by fracturing of each component is of interest. However, in comparison to MTD1, MTD3 is remarkably time consuming.

Behaviour of shear tab connections in column removal scenario

Shear tabs are one of the simplest and the most cost-effective connections in steel frame construction and their behaviour under conventional loading has been well studied. However, their behaviour is highly complex under the scenario when an adjacent column is compromised and this is the subject of ongoing research. In this study, detailed finite element analyses of shear tab connections with three, four or five bolts are performed and the results are compared with available experiments. Characteristic phenomena of the connection, including rotational capacity and failure modes under the column removal scenario, are studied and discussed. The results are compared with available codes and guidelines and new equations are proposed that predict the rotational capacities of shear tab connections for progressive collapse analysis. The shear-axial-moment interaction curves for the connections under study are developed and examined, and conclusions are made based on the observed behaviour. The research uses high-fidelity finite element models of shear tab connections to study both load evolution and failure modes. These models shed more light on the performance and the sources of ductility in shear tab connections. The results can be used to select suitable connection modelling parameters for progressive collapse evaluations of steel frames with similar shear connections.

Adaptive superelement modeling for progressive collapse analysis of reinforced concrete frames

A new adaptive superelement procedure for progressive collapse analysis of 2D reinforced concrete frames under column removal scenario is proposed. Superelement formulation is employed to reduce the computational cost. In addition, a new procedure for rigid body rotation correction is proposed to improve the accuracy of the superelement formulation. An error indicator is developed to monitor the propagation of the nonlinear zone during analysis. The adaptive analysis procedure is then formed by combining the error indicator with a reliable member and substructure collapse identification algorithm. Numerical examples are given to demonstrate the accuracy, robustness and efficiency of the modeling procedure. As the work involves establishing a novel concept to reduce computational effort when simulating the whole process of collapse, the authors only consider the impact energy of falling objects in a quasi-static manner through the use of dynamic increase factors, thereby obviating the need for time-consuming nonlinear structural dynamic analysis.

Residual ultimate strength assessment of double hull oil tanker after collision

The aim of the present study is the assessment of a residual ultimate strength of an Aframax-class double hull oil tanker damaged in collision. A contribution to the research of the problem is given in a systematic investigation of the influence of the rotation of neutral axis (NA), which is performed by imposing appropriate boundary conditions. Nonlinear finite element method (NFEM), using explicit dynamic integration method implemented in LS-Dyna, is employed. NFEM results are compared with the IACS CSR progressive collapse analysis (PCA) method. Residual strength diagrams are developed for a rapid residual ultimate longitudinal strength assessment in both sagging and hogging and accounting for correction factor because of the rotation of NA. Following this, developed diagrams are compared with previously published researches. The results of this study may be used by classification societies in a Rules development process, in the risk assessment studies of the maritime transportation and for a quick calculation of the hull girder residual strength of a damaged ship in the situation requiring emergency response action.

Effects of Masonry Infill Wall on the Performance of RC Frames to Resist Progressive Collapse

Masonry-infilled (MI) panels, which serve as partitions in buildings, are normally considered as architectural elements. Their weights are considered in progressive collapse analysis, but the resistance of the walls is normally ignored in design guidelines. Simple structural analysis predicts that the infill walls, which are commonly equivalent to compressive struts, increase not only the lateral load resistance but also the vertical load resistance of the reinforced concrete (RC) frames. Because extra vertical resistance might reduce the risk of failure, it is necessary to quantify the effects of MI walls on the load resisting capacity of RC frames to mitigate progressive collapse. However, few studies, especially experimental studies, have been carried out on this topic. Thus, six multistory by multibay RC subframes were designed and tested, subjected to push-down loading regimes. The six subframes were categorized into two groups: (1) bare frames without MI walls and (2) infilled frames with MI walls. The failure modes, load-displacement curves, deformation shapes, and strains of the specimens are measured and compared. The effects of the MI wall on the load resisting capacity, initial stiffness, and load resisting mechanisms of RC frames to resist progressive collapse were also evaluated and discussed. The experimental and analytical results indicated that ignoring the effects of MI walls in progressive collapse design may result in substantial inaccuracy in predicting the stiffness, strength, and failure modes of infilled frames to resist progressive collapse. Infill walls with low height/span ratio may fail in splitting of the equivalent compressive struts prior to crushing.

Probabilistic progressive collapse analysis of steel frame structures against blast loads

Abstract This study investigates the failure probability of steel frame structures against terrorist attack from Vehicle Borne Improvised Explosive Device (VBIED). A two-step approach is used to evaluate the collapse potential of structures against blast loads. In the first step, the damage degree and responses of structural members under blast loads are determined based on an equivalent single–degree of freedom system. In the second step, the post-blast collapse behavior of steel frame structures is investigated using a 3-D nonlinear macro-based numerical model. To improve the computational efficiency, the failure probability is calculated using subset simulation method cooperated with an advanced Delayed Rejection Adaptive Markov Chain Monte Carlo simulation algorithm. The variability of blast load, vertical gravity load and structural material properties are considered. The computational framework is applied to a prototype 10-story steel frame to study the failure risk against VBIED. The results show that the reliability assessment framework used in this study provides an accurate and more efficient prediction of failure risk of structures against blast loads compared with the direct Monte Carlo simulation method. The framework also presents an approach for determination of effective measures in protecting structures against blast loads.

Progressive collapse analysis of a typical RC high-rise tower

The world has recently witnessed tremendous increase in terrorist activities. This led to the requirement of blast resistant design of structures. The progressive collapse of structures, being the most severe consequence of blast generated waves, has been the subject of several studies. Although structural engineers are developing methodologies for the mitigation of progressive collapse, there is a lack of adequate tools that can be employed for simulating and predicting the progressive collapse response of structures with acceptable confidence. An attempt has been made in this paper to develop a practical and acceptable procedure for the progressive collapse analysis of reinforced concrete (RC) framed structures. The adequacy of the procedure has been demonstrated by studying the progressive collapse behavior of a typical RC framed high-rise building in Riyadh when exposed to blast generated waves.

Distributed Column Damage Effect on Progressive Collapse Vulnerability in Steel Buildings Exposed to an External Blast Event

AbstractRecent terrorist attacks on civil engineering infrastructure around the world have initiated extensive research on progressive collapse analysis of multistory buildings subjected to blast l...

Applications of stiffness-based evaluation method to element importance of truss systems

Two structural performance indexes, making use of eigenvalues of stiffness matrix, are presented in the study for the evaluation of element importance in the progressive collapse analysis of space trusses. Both indexes are based on the consensus that the element transferring higher loads in the load path is generally more important in the structural sys­tem. The first index is formulated as change of the smallest stiffness after removal of specific element, and the second in­dex is defined as determinant of the stiffness matrix. Several simple numerical examples are presented to investigate per­formance of the proposed indexes; and finally, a square pyramid space grid system is studied as an illustrative example.

Effect of Earthquake characteristics on seismic progressive collapse potential in steel moment resisting frame

According to the definition, progressive collapse could occur due to the initial partial failure of the structural members which by spreading to the adjacent members, could result in partial or overall collapse of the structure. Up to now, most researchers have investigated the progressive collapse due to explosion, fire or impact loads. But new research has shown that the seismic load could also be a factor for initiation of the progressive collapse. In this research, the progressive collapse capacity for the 5 and 15-story steel special moment resisting frames using push-down nonlinear static analysis, and nonlinear dynamic analysis under the gravity loads specified in the GSA Guidelines, were studied. After identifying the critical members, in order to investigate the seismic progressive collapse, the 5-story steel special moment resisting frame was analyzed by the nonlinear time history analysis under the effect of earthquakes with different characteristics. In order to account for the initial damage, one of the critical columns was weakened at the initiation of the earthquake or its Peak Ground Acceleration (PGA). The results of progressive collapse analyses showed that the potential of progressive collapse is considerably dependent upon location of the removed column and the number of stories, also the results of seismic progressive collapse showed that the dynamic response of column removal under the seismic load is completely dependent on earthquake characteristics like Arias intensity, PGA and earthquake frequency contents.

Progressive collapse analysis of long-span transmission tower-line system under multi-component seismic excitations

Research on progressive collapse has a practical significance for long-span transmission tower-line system. Considering material damage effect, the Tian–Ma–Qu model is used to capture the nonlinear...

Progressive collapse analysis of buildings with concentric and eccentric braced frames

In this study, the susceptibility of different symmetric steel buildings with dual frame system to Progressive Collapse (PC) was assessed. Some ten-story dual frame systems with different type of braced frames (concentrically and eccentrically braced frames) were considered. In addition, numbers and locations of braced bays were investigated (two and three braced bays in exterior frames) to quantitatively find out its effect on PC resistance. An Alternate Path Method (APM) with a linear static analysis was carried out based on General Services Administration (GSA 2003) guidelines. Maximum Demand Capacity Ratio (DCR) for the elements (beams and columns) with highest DCRs (DCRmoment and DCRshear) is given in tables. The results showed that the three braced bays with concentric braced frames especially X-braced and inverted V-braced frame systems had a lower susceptibility and greater resistance to PC. Also, the results represented that the beams were more critical than columns against PC after the removal of column.

A proposed procedure for progressive collapse analysis of common steel building structures to blast loading

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.