Fire-induced Progressive Collapse Research Articles

Progressive collapse resistance of self-resilient composite frames under fire conditions

Self-resilient composite frames exhibit robust resistance to progressive collapse and excellent seismic performance. However, their behavior under fire conditions is inadequately explored. This study investigates the collapse resistance mechanisms and response of self-resilient composite frame substructures (SRCFS) under fire-induced progressive collapse. A three-dimensional finite element model was developed, incorporating temperature-dependent thermal and mechanical properties of concrete and steel. Sequentially coupled thermal-mechanical analysis was conducted using the ABAQUS/Explicit solver in a quasi-static manner. Existing experimental data at both ambient and high temperatures were used to validate the proposed model. The study analyzed the contributions of steel beams and strands to vertical resistance, examining their impact on the collapse-resistance mechanism through a constant load-heating transient loading scheme. Structural responses under ambient and fire conditions were compared, focusing on different damage mechanisms. The effects of initial prestressing of strands, angle gauge length, angle thickness, and various heating curves on collapse resistance were evaluated. Findings suggest that the ISO-834 standard's failure criterion is overly conservative for SRCFS, as it neglects the enhanced load-carrying capacity provided by tensile catenary action. This mechanism offers additional escape time, enhancing personnel safety. The study identifies factors influencing the performance of SRCFS against progressive collapse under fire and proposes design recommendations.

Simplified analytical model for prediction of collapse resistance of restrained steel beam-column substructure exposed to fire

This paper provides a simplified analytical model for the restrained steel beam-column substructure under a fire-induced progressive collapse scenario, which is applied to predict the collapse resistance of substructures under fire. The simplified model is formulated for axially and rotationally restrained two-span steel beam-column substructures under column-loss scenarios and involves rigid and semi-rigid connections. The response characteristics of restrained substructures exposed to fire under column-loss scenarios in each response stage are elaborately analyzed. A “negative” catenary stage, in consideration of the unique negative axial force effects induced by the temperature thermal expansion, was first introduced in the five-stage simplified model for restrained substructures exposed to fire against progressive collapse. Subsequently, the explicit calculation formulas for determining the vertical loads and deflection of both rigid and semi-rigid joint substructures exposed to fire were derived in a quantified way, based on rigid-plastic mechanisms and restraint coefficient methods. In addition, the corresponding numerical simulation analysis on a restrained two-span steel beam-column substructure with different end constraints and fire conditions was carried out to verify the applicability and reliability of established theoretical formulas. Comparisons of vertical load-deflection relationships between the calculation formulas and corresponding numerical simulation shows good accuracy. For more accurate prediction results, the error analysis was further conducted, and several theoretical formulas were modified, which were verified to be accurate and reliable after correction. With derived resistance functions, the resistance of steel beam-column substructures in fire-induced progressive collapse scenarios can be predicted.

Modeling parameters for predicting the fire-induced progressive collapse in steel framed buildings

Fire is one of the extreme loading events that a building may experience during its service life and can have severe consequences on the safety of its occupants, first responders, and the structure. Steel framed buildings under severe fires can experience high levels of instability at a local or global level, which in turn can lead to the partial or progressive collapse of the structure. However, in current practice, fire resistance of structures is obtained without due consideration to a number of critical factors, and this is mainly due to the high level of complexity in undertaking advanced analysis of structures under fire exposure. This paper presents a parametric study on a ten-story braced steel framed building subjected to fire exposure wherein six different parameters are evaluated: fire severity, fire spread, load paths, temperature-induced creep, local instability, and analysis regime. Results from validated finite element models are utilized to evaluate the influence of the different parameters and recommend critical parameters to be incorporated in the analysis. Results show that the susceptibility of fire-induced progressive collapse significantly depends on the severity of the fire exposure scenario, including fire intensity, fire spread, and extent of burning. Also, accounting for the full effects of transient creep in fire-induced progressive collapse analysis is needed to obtain conservative failure times under severe to very intense fire exposure. Additionally, results from the parametric study infer that the sectional classification of a steel section based on local instability can alter under fire exposure and this effect is more critical in steel columns located in the higher stories of the building; a nonslender column at ambient conditions can transform to a slender section at elevated temperatures. This can induce temperature-induced local instability in the column and lead to an early onset of instability at member and structural levels.

Progressive collapse resistance of reinforced concrete beam-column connection under fire conditions

To reveal the reinforced concrete (RC) structural response under fire-induced progressive collapse scenarios, 3D finite element (FE) models were developed to investigate the effect of high temperatures on the collapse resisting mechanisms of RC beam-column connections. To describe the behavior of RC connections at elevated temperatures, temperature-dependent thermal and mechanical properties of concrete and reinforcing steel were adopted in the 3D FE model. The sequentially coupled thermal–mechanical analysis was performed with the explicit solver in a quasi-static manner. The concrete damaged plasticity (CDP) and ductile damage for metals (DDM) were adopted to better describe the failure of concrete and steel rebar, respectively. The proposed numerical model was validated by experimental data at different temperatures from literature. To understand better the collapse resistance of RC beam-column connections, a new loading scheme was adopted in the developed model. The load capacity of RC connection under fire conditions was investigated analytically and numerically. The effects of top and bottom reinforcement ratios, concrete strength, beam depth and fire severity on the collapse resisting mechanisms were investigated. The regulated chord rotation failure criteria recommended by the U.S. Department of Defense (DoD) were utilized and showed to be conservative on the collapse identification of RC structures under fire conditions.

Effect of fire on behavior of RC beam-column assembly under a middle column removal scenario

Fire is one of the accidental loads that can result in the progressive collapse of buildings. To investigate the structural behavior of reinforced concrete (RC) structures subjected to fire-induced progressive collapse, the sequential thermal-mechanical coupling (STMC) method is adopted. The STMC method includes two steps: firstly, the fire effects (temperature field) on the material properties of concrete and reinforcement are simulated. Secondly, the results of the first step are set as the initial condition of the RC beam-column assembly to study the structural behavior of the assembly subjected to a middle column removal scenario. The reliability of the simulation method is validated against the available test results. The influences of fire duration and fire range are studied based on the validated numerical model. It is found that the load resistance and deformation capacity decrease significantly as the fire duration exceeds 30 min. The load resistances of the RC beam-column assemblies under the fire durations of 30 min, 60 min, and 90 min are 35%, 26%, and 21% of that of the RC beam-column assembly under the ambient temperature, respectively. Fire duration of 18 min is found to be the critical one, less than and greater than which the failure of the RC beam-column assembly is controlled by the fracture of the beam bottom rebar near the middle column and the fracture of the beam top rebar at the location of rebar termination, respectively. The RC beam-column assembly subjected to a single-bay in fire scenario shows asymmetric structural behavior. Compared with RC beam-column assemblies under two-bay in fire scenario, the load resistances of RC beam-column assemblies subjected to single-bay in fire scenario are greater by 6%–30%. However, they achieve a similar deformation capacity as the failure of the RC beam-column assemblies subjected to single-bay in fire scenario is controlled by the failure of the bay in fire.

Developments and research on fire-induced progressive collapse behaviour of reinforced concrete elements and frame - a review.

Many studies have been carried out for understanding the mechanism of failure of RC structural systems under varying temperature circumstances. Similarly, several methods have been developed for improving the fire resistance of concrete buildings, with respect to material selection and detailing aspects. However, only some of the researchers have concentrated on composite behavior of interaction between the structural elements and functional elements, like interaction between masonry infill walls and RC frame elements in the emergence of fire. Several numerical models have been developed for analysis of infilled frames. For simulating the action of fire on full-scale reinforced concrete buildings, three factors, namely, presence of loading, place of fire, its intensity, and duration, must be considered since the material behavior depends on the stress level, intensity and duration of fire and the sensitiveness of structural element to the location and application of fire. To consider the combined effect of load and high temperature, finite element analysis is used. For simulating the intensity and time factor for temperature rise, transient state studies must be done.

Analysis of fire-induced progressive collapse for topside structures of a VLCC-class ship-shaped offshore installation

ABSTRACT This study extends the authors’ previous numerical and experimental studies simulating the progressive collapse of steel stiffened-plate structures in fire events (Paik JK, Ryu MG, He KH, Lee DH, Lee SY, Park DK, Thomas G. 2021a. Full-scale fire testing to collapse of steel stiffened plate structures under lateral patch loading (part 1) – without passive fire protection. Ships Offsh Struct. 16(3):227–242; Paik JK, Ryu MG, He KH, Lee DH, Lee SY, Park DK, Thomas G. 2021b. Full-scale fire testing to collapse of steel stiffened plate structures under lateral patch loading (part 2) – with passive fire protection. Ships Offsh Struct. 16(3):243–254; Ryu MG, He KH, Lee DH, Park SI, Thomas G, Paik JK. 2021. Finite element modeling for the progressive collapse analysis of steel stiffened-plate structures in fires. Thin-Walled Struct. 159:107262). Specifically, this study demonstrates that the computational models developed in the earlier studies can be applied to the analysis of the heat transfer and fire-induced progressive collapse behaviour of the topside structures of a ship-shaped offshore installation. To this end, a hypothetical VLCC-class floating, production, storage and offloading (FPSO) unit hull structure is considered, and transient thermal elastic-plastic large-deformation finite element models are used. The novelty of this study and its contribution to industry are the development of a practical procedure to ensure the fire safety of large-scale steel-plated structures with complex geometries.

A review on research of fire-induced progressive collapse on structures

PurposeThis paper delineates a literature review on fire-induced progressive collapse on structures and the effect of high temperature on structures and elements. After the occurrences of fire in the World Trade Center in the USA, the researchers started concentrating on the progressive collapse that happens due to high temperature. Currently, most of the researchers are working on fire-induced progressive collapse on structures using high-temperature behavior on materials which are used for construction. The researchers have been doing an intensive study to find a better strategy to prevent the building from structural fire damage or collapse with available codes and guidelines throughout the world. This paper aims to provide a better understanding and analytical solutions on the basis of the recent works done by researchers in fire-induced progressive collapse and methods adopted to find the collapse mechanism.Design/methodology/approachThis paper is written by studying different literature papers of 109 related to progressive collapse on structures and fire-induced progressive collapse.FindingsThe behavior of structures due to high temperature and collapse conditions due to fire in different scenarios is identified.Originality/valueThis paper fulfills an identified need to study how the structure can withstand high-temperature conditions in our day-to-day lives.

Finite element modeling for the progressive collapse analysis of steel stiffened-plate structures in fires

This paper is a sequel to the authors’ articles which provided the test data on the progressive collapse of full-scale steel stiffened-plate structures without and with passive fire protection (PFP) under lateral patch loading in fires [1,2]. This paper presents new computational models for the analyses of heat transfer and fire-induced progressive collapse behaviour of steel stiffened plate structures without or with PFP. For this purpose, transient thermal elastic-plastic large-deformation finite element models were formulated. The developed computational models were validated by a comparison with the test data. The novelty of the paper is associated with a new procedure for the fire-induced progressive collapse analysis of steel stiffened-plate structures which is critical for a contribution to fire safety engineering of steel plated structures.

Evaluation of Plasco Building fire-induced progressive collapse

This paper presents a comprehensive structural assessment of the fire-induced progressive collapse of Plasco Building, in January 2017. The assessment employs a three-phase approach: a) field investigation to collect data about the building and the event, b) structural evaluation against service loads, c) progressive collapse analysis. A collapse scenario is proposed, which is simulated using finite element modelling and numerical analysis. The results showed the adequacy of the building for service loads, while its significant vulnerability against progressive collapse. The vulnerability was mainly due to the lack of adequate continuity, ductility, and redundancy to resist the spread of damage. The weakest link in the structural system was the beam to column connections, which reached their critical temperatures first and failed to resist the local failure loads. Furthermore, exposure of unshielded structural components to the fire had led to a more severe condition, which eventually by the occurrence of failures over consecutive stories, buckling of the columns, and significant change in the geometric shape of the structure, the total collapse of the building occurred. The results of this investigation are considered as valuable tools for recognizing the deficiencies of the structural provisions in Iran against such events.

Fire-induced progressive collapse mechanisms of steel frames with partial infill walls

This paper presents a numerical investigation on progressive collapse mechanisms of steel frames with partial infill walls under fire scenarios using ABAQUS platform. The load redistributions and collapse mechanisms of steel frames subjected to different fire scenarios (edge bay and central bay fires) are studied. The influences of strength, opening percentage and layout of partial infill walls are also analyzed. The results of the numerical analysis indicate that the presence of partial infill walls causes combined tensile force and bending moment at the ends of surrounding beams. The strut action of partial infill walls and the overturning moment imposed by the frame in the collapse bay are identified as load redistribution mechanisms of the steel frame. The steel frame using higher strength steel, more number and lower opening percentage of partial infill walls collapses at higher temperatures. Furthermore, the analyses identify three deformation modes of beams depended on the layout of partial infill walls. Finally, a preliminary design method based on equivalent compressive strut model is proposed with good accuracy, in order to prevent the steel frame with partial infill walls from fire-induced collapse in engineering practice.

A non-iterative progressive collapse design method for RC structures based on virtual thermal pushdown analysis

Disproportionate progressive collapse is a structural failure mode with low probability and high consequences. Due to this nature, progressive collapse design is usually treated as a secondary design; namely, a design check after the design for primary loadings. Various design procedures have been recommended, notably the alternate load path method through nonlinear pushdown analyses. However, most of these design procedures are iterative by nature to satisfy the design acceptable criteria. To improve the design efficiency, this study presented an innovative design technique that allows to directly determine the proper amount of reinforcement in beams and slabs of a reinforced concrete (RC) structure in order to withstand the gravitational loads under column removal scenarios. Inspired from fire-induced progressive collapse research, the proposed method employs a virtual thermal pushdown analysis, in which the temperature increase affects only the strength of reinforced steel. With carefully developed strength-temperature relationships of the rebars, the virtual thermal analysis produces a displacement-temperature curve that represents the genuine nonlinear relationship between the amount of reinforcement and structural performance (often represented by vertical displacement). This curve is then used to directly determine the amount of reinforcement at the prescribed performance target. Two beam-column sub-assemblage examples and the Alfred P. Murrah Federal Building were analyzed and redesigned to demonstrate the effectiveness of the proposed method. All three examples showed that the proposal virtual thermal pushdown method can accurately determine the appropriate amount of reinforcements to meet the performance target.

Technical and Administrative Assessment of Plasco Building Incident

In this study, the fire-induced progressive collapse of Plasco building incident is briefly assessed from different perspectives including: (1) the most probable building collapse scenario, (2) the structural deficiencies causing the progressive collapse, (3) the key problems in the electrical and mechanical installations leading to the fire outbreak, (4) the problems in building maintenance and up keeping procedures according to the Iranian requirements, (5) the simulation of the fire and smoke propagation during the incident, and (6) the strengths and weaknesses of the crisis management procedure. The results showed that the start of the fire and its spread was the consequence of two combined sources: the non-standard maintenance of the building and its installations throughout the entire service life of the building and the lack of a fire safety system in the building in accordance with the requirements of Iranian national building codes. Finally, to reduce such catastrophic risks in the high-risk buildings in Tehran and to reduce losses in probable similar events, a risk-reduction program is proposed. The program is intended to be used in the present rules, regulations, and standards implementation and also in resolving imperfections of the existing regulations in the field of rehabilitation and maintenance of old buildings.

Fire-induced Progressive Collapse of 3D Steel Portal Frames

Abstract This paper presents experimental and numerical investigations on progressive collapse of 3D steel portal frames exposed to fire. A natural fire test was carried out on a 36m×12m full-scale steel portal frame. A finite element model is established and validated against the test results. The experimental results show that the frame collapses after 15 mins of heating due to the buckling of the heated columns. It is found that the adjacent frame column at mid-span moves outward, compared to the inward movement of columns at corner. The numerical results show that the fire protection had significant effect on the collapse mode. The protected portal frames show a lateral drift collapse mode, compared to a downward collapse mode for unprotected frames. A higher level of fire protection leads to longer buffer time to delay the collapse of frames.

Progressive Collapse Analysis of a Typical Super-Tall Reinforced Concrete Frame-Core Tube Building Exposed to Extreme Fires

A number of disastrous incidents have indicated that extreme fires can act as a trigger event to initiate the progressive collapse of reinforced concrete (RC) structures. Hence, research on progressive collapse risks of RC structures under extreme fires is most important. However, limited studies have been undertaken in the fire-induced progressive collapse of tall and super-tall RC buildings. Hence, a high-performance finite element model was developed for this study to simulate the mechanical behavior of RC members in fire-induced progressive collapse. Fiber beam and multi-layer shell elements were used, in conjunction with appropriate material constitutive laws and elemental failure criteria under high temperature conditions. Extreme fire scenarios were also considered, based on the actual fire-induced progressive collapse events of the WTC towers and the Windsor Tower. The simulation results indicated that a progressive collapse of a super-tall building was triggered by the flexural failure of the peripheral columns, approximately 7 h after being exposed to fire. The bending deformations of the peripheral columns increased significantly, due to the outward thermal expansion of the upper floors and the inward contraction of the lower floors, a result of the fire-induced damage. The results also revealed that, when multiple stories are subjected to fire, the internal forces in the components are redistributed in the horizontal and vertical directions by way of the Vierendeel truss mechanism, leading to a maximum increase (of approximately 100%) of the axial forces in the columns. The present work identified the mechanisms of the fire-induced progressive collapse of a typical RC super-tall building, and provided an effective analysis framework for further research on the fire safety of tall and super-tall RC buildings.

Fire safety assessment of super tall buildings: A case study on Shanghai Tower

Shanghai Tower is an existing super high-rise building composed of mega frame-core-outrigger lateral resisting systems. Its structural safety in fire has been given great attention. This paper presents an independent review of the performance of Shanghai Tower in case of fire. Two fire scenarios: standard fires and parametric fires have been considered. The fire resistance of key component, including the concrete core, mega columns, the composite floor, outrigger trusses and belt trusses were examined first. Their real fire resistance periods proved to be far beyond the design fire resistance. The components with weak fire resistance such as peripheral steel columns and web members of belt trusses were then removed to study the resistance of the residual structure against progressive collapse. The results show that Shanghai Tower has a minimum of 3h fire resistance against fire-induced progressive collapse. The concrete components have smaller residual displacements compared to the steel components. It is recommended, for the design of other similar structures, that effective fire protection should be provided for the outrigger trusses to guarantee the connection between the core and mega columns.

Threat-Independent Column Removal and Fire-Induced Progressive Collapse: Numerical Study and Comparison

Progressive collapse is defined as the spread of an initial failure from element to element, eventually resulting in the collapse of an entire structure or a disproportionately large part of it. The current progressive collapse analyses and design methods in guidelines and codes focus on the alternate load path method. This method is suitable especially in the case of blast-induced progressive collapse. In this paper, fire-induced and threat-independent progressive collapse potential is numerically investigated in steel moment resisting frames. Affecting parameters such as location of initial failure and number of floors are considered in this study. Two different mechanisms were observed in threat-independent and fire-induced progressive collapse: while in threat-independent column removal alternative load paths play major role, in fire-induced progressive collapse the weight of the structure above the failure region is the most important parameter.

A Case Study on a Fire-Induced Collapse Accident of a Reinforced Concrete Frame-Supported Masonry Structure

In 2003, an 8-storey reinforced concrete (RC) frame-supported masonry structure, located in Hengyang City, China, underwent a severe fire-induced collapse accident. Information on the structure and the fire scenario is presented. It includes the design data, the site observation record of the fire incident, and the laboratory material test results. Preliminary investigation reveals that about 45.9% of the bottom storey of the RC frame experienced temperatures in excess of 800°C, and its central area reached 1300°C. Such a severe fire load, of fairly high temperature and large area, is thought to be the primary cause of the progressive collapse of the entire building structure. To better understand the collapse mechanism, this study presents a coupled thermo-mechanical numerical simulation of the building collapse. The actual collapse area is well reproduced by the proposed numerical model. The simulation further demonstrates that the initial damage happened to two interior columns exposed to temperature of 1300°C. Such damage was also attributable to the large gravity load they carried, and the complicated nature of the local structural arrangements. The adjacent structural members were subsequently damaged, because they were also weakened by the fire, and were over-loaded by the redistributed load. Failure of the two interior columns and adjacent area eventually triggered a progressive collapse. Further, the effect of some critical factors on the collapse mechanism is discussed. On the basis of this numerical case study, practical design considerations on the key structural components, the fire compartments, and the structural robustness are given for the prevention of the fire-induced progressive collapse of RC frame structures.

Effect of Bracing Systems on Fire-Induced Progressive Collapse of Steel Structures Using OpenSees

This paper investigates the effect of various bracing systems on the fire-induced progressive collapse resistance of steel-framed structures using OpenSees. Two types of bracing systems (vertical and hat bracing) and various fire scenarios (single and multi-compartment fires) are considered. Four collapse mechanisms of steel frames in fire are found through parametric studies. General collapse is characterized by the collapse of the heated bay followed by lateral drift of adjacent cool bays. Global collapse of a whole frame is due to the buckling of ground floor columns. Another two lateral collapse modes (local and global) are caused by catenary action developed in the heated beams under large deflections. Vertical bracing systems have positive effects on increasing the lateral restraint of the frame against local or global drift, while when arranged at edge bays of frames they negatively contribute to the spreading of a local damage to global collapse in the form of sequential buckling of adjacent columns through load-transfer mechanisms. For a more realistic arrangement of vertical bracings inside the frame, the bracing acts as a barrier to restrain the spread of local damage to the rest of the frame. Instead, using hat bracing can effectively optimize the load-transfer path through a more uniform redistribution of loads in columns and enhance the resistance of structures against progressive collapse. It is found that the application of vertical bracing systems alone on the steel frames to resist progressive collapse is proved to be unsafe and a combined vertical and hat bracing system is recommended in practical design.

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.