Progressive collapse potential of a typical steel building due to blast attacks (original) (raw)
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Numerical Analysis for Progressive Collapse Potential of a Typical Framed Concrete Building
Recent historic events have shown that buildings that are designed in compliance with conventional building codes are not necessarily able to resist blast effects. It was observed in the past events that progressive or disproportionate collapse generally occurred due to deficient blast performance of the structure, albeit in compliance with conventional design codes. In the past, safety of structures against blast effects was ensured, to a limited extent, through perimeter control; which minimizes damage by preventing the direct impact of the blast effects on the building. With the emergence of blast resistant structural design, methodologies to inhibit progressive collapse through the structural components performance can be developed, although there are no available adequate tools to simulate or predict progressive collapse behaviour of concrete buildings with acceptable precision and reliability. This paper presents part of an effort to find an affordable solution to the problem. S tate of the art review of the blast analysis and progressive collapse analysis procedures will be presented. Preliminary analysis has been carried out to establish the vulnerability of a typical multistorey reinforced concrete framed building in Riyadh when subjected to accidental or terrorist attack blast scenarios. In addition, the results of the blast vulnerability assessment will be used to develop mitigation approach to control or prevent progressive collapse of the building.
Nowadays, as a result of increased terrorist and bomb attacks throughout the globe in the vicinity of strategic buildings, designing these structures against impact loads, particularly the blast-related ones, has been taken into more consideration. The current procedure for designing the structure against an explosion is a design against the local failure of the current elements in the first step and then, in the next step, against local damage as well as tactful thinking to prevent this damage from spreading to other parts of the structure. The present research investigates the impacts of explosives, derived from probable terror-stricken scenarios inside and outside a strategic four-story steel building with a special moment frame system. Then, the resistive capacity of the damaged building (due to blast) has been evaluated against the progressive collapse, and finally, the rate of the collapse risk and the reliability of the structure have been obtained by presenting a probable method. Thus, the vulnerable parts inside and outside the building are identified and safety measures have been determined, so that in case of no safety or excessive collapse risk-access to dangerous parts of the building could be reinforced or limited. Results show that progressive collapse probability and reliability of the building are 57% and 43% respectively.
WSEAS International Conference on ENGINEERING MECHANICS, STRUCTURES, ENGINEERING GEOLOGY (EMESEG '08), 2008
The loading produced by blast events are typically much higher than the design loadings for which an ordinary structure is designed. These loadings, referred to as overpressures in the technical literature, are beyond the capacity of the structure and local failure of structural elements in the region of the explosion is likely. For such loadings, component and system ductility can be utilized to avoid system collapse. Progressive collapse occurs when a structure has its loading pattern, or boundary conditions, changed such that structural elements are loaded beyond their capacity and fail. The residual structure is forced to seek alternative load paths to redistribute the load applied to it. As a result, other elements may fail, causing further load redistribution. The process will continue until the structure can find equilibrium either by shedding load or by finding stable alternative load paths. As a case study for this paper the main substation building located at Esfahan refinery plant in Iran is considered. A nonlinear static analysis is used to assess accurately the post attack behavior of structural elements that are not removed from the building by the blast loads in their corresponding damaged states.
Dynamic response and robustness of tall buildings under blast loading
Journal of Constructional Steel Research, 2013
Recently, extensive research has been focused on the progressive collapse analysis of the multi-storey buildings. However, most of the research is based on the Alternative Path Method (APM) with sudden removal of the columns, ignoring the duration of the blast load working on the structures. In this paper, a 3-D numerical model with the direct simulation of blast load is proposed to study the real behaviour of a 20 storey tall building under the blast loading. A typical package bomb charge of 15 kg was detonated on the 12 th floor. The corresponding dynamic response of structure was studied in details. The robustness of the building under blast load was assessed. Comparison between the proposed method and the APM was also made. It is found that, due to the uplift and downward pressure working on the slab, the column force under the direct blast simulation method is smaller than that of the alternative path method. The method to enhance the robustness of the buildings is also recommended.
"A REVIEW STUDY ON STEEL STRUCTURE SUBJECTED TO BLAST LOADING"
IRJET, 2023
The recent terrorist assaults on the infrastructure have severely damaged property and lives, necessitating in-depth study of the progressive collapse analysis of multi-story buildings subjected to blast loading. Typically, much of the research is centered on Alternate Path Method (APM) with sudden column removal, ignoring the optimal site of the blast loading. A 3D model of a 12-story steel building with a direct simulation of the blast load is suggested in this thesis. Additionally, the effect of blast loading at various places has been investigated. Vehicle-borne and package-borne blast events have both been taken into consideration. The blast load is analytically determined by the numerical model of the structure, which was developed using the "SAP 2000" software. The published example of a tubular steel beam subjected to blast loads is used to validate the numerical model. On the basis of the results of the final analysis, suggestions have been made to prevent the collapse of steel buildings.
The response of tall buildings has been a major concern in metropolitan cities, especially with the recent surge in extreme activities targeted at structures with viable commercial values. This paper discusses a study carried out on the structural behaviour of a 2D frame, modelled to represent a tall building with ABAQUS. The model frame was subjected to a charge of the equivalent weight of 1 ton of TNT but placed at two varying cases of 5 and 10-m standoff distances. Plane-strain elements that incorporate the feature of material nonlinearity were utilized to model the structural components of the building and the simulated blast overpressures were obtained from the CONWEP software. The effects of large deformations of beams and columns corresponding to the short time loading duration depicted by the explosions were analysed from a local perspective. The extent of the damage is based on a local index defi ned as the ratio of curvatures. These local indices are consequently used to determine the possibility of disproportionate collapse of the frame from a global perspective. Finally, the provision of more ductile structural detailing is recommended to enhance the structural integrity of the building, increasing its resilience against blast attacks.
IJERT-Numerical Analysis of Steel Building Under blast Loading
International Journal of Engineering Research and Technology (IJERT), 2014
https://www.ijert.org/numerical-analysis-of-steel-building-under-blast-loading https://www.ijert.org/research/numerical-analysis-of-steel-building-under-blast-loading-IJERTV3IS110846.pdf Explosions are widely used for demolition purpose such as in construction or development works, military applications and destruction. But also it is common to use in terrorist activities and easy to produce with a great power to cause structural damage and injuries.The aim of the paper is to understand the explosion phenomena and its load on structures by introducinga historical studies and equations.Moreover, finite element program SAP2000 was conducted to study and analyze the real behavior of steel structure which subjected to blast loads withdifferent charge weights at the same building situation.The main parameters considered in this study were displacement, terrorist threat and demand capacity ratio (D/C). The blast load was determined as a pressure-time history.
Numerical analyses for the structural assessment of steel buildings under explosions
2013
This paper addresses two main issues relevant to the structural assessment of buildings subjected to explosions. The first issue regards the robustness evaluation of steel frame structures: a procedure is provided for computing “robustness curves” and it is applied to a 20-storey steel frame building, describing the residual strength of the (blast) damaged structure under different local damage levels. The second issue regards the precise evaluation of blast pressures acting on structural elements using Computational Fluid Dynamic (CFD) techniques. This last aspect is treated with particular reference to gas explosions, focusing on some critical parameters (room congestion, failure of non-structural walls and ignition point location) which influence the development of the explosion. From the analyses, it can be deduced that, at least for the examined cases, the obtained robustness curves provide a suitable tool that can be used for risk management and assessment purposes. Moreover, the variation of relevant CFD analysis outcomes (e.g., pressure) due to the variation of the analysis parameters is found to be significant.
Progressive collapse in multi-storey steel frames
2011
Following the collapse of the Ronan Point apartment tower, provisions to minimise the potential for progressive collapse were introduced in design codes for the first time. In recent years, the increased threat of terrorism has highlighted the importance of such robustness requirements. This paper presents a methodology to assess the extent of damage to a multi-storey structure following localised collapse. This is accomplished through the design of an algorithm, based on the notional element removal method. By systematically considering the effects of damage to all members in a structure, this algorithm can be used as both a design and an analysis tool to identify whether a structure is unduly sensitive to the effects of localised damage. This paper describes the key features of this analysis program. Additionally, the results of a study to determine the effect of column spacing on the response of a damaged structure are presented.