Dynamic Structural Behavior of Bridge Components under Explosive Effects (original) (raw)
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Since the collapse of the WTC towers in September 2001, concern about the protection of buildings and infrastructures against blast loads has increased significantly. Comprehensive experimental and numerical studies of blast loading effects on buildings have been carried out in recent years, whereas for bridge engineers, blast-resistant design is still a new area which requires separate and systematic investigation. The objective of this paper is to simulate the performance of three modern types of reinforced concrete bridges under various blast loads, including a slab-on-girder bridge, a box-girder bridge and a long-span cable-stayed bridge. To solve the computational constraints in performing numerical analysis on a personal computer, a Multi-Euler domain method based on the fully-coupled Lagrange and Euler models is adopted and further developed for long-span bridge application. This study investigates various detonation scenarios in terms of the explosive weight and location, and their interactions with bridge structures. Both the localized damage mechanism and the global structural response of three bridges are examined. By studying the blast-resistance of each bridge under different explosion threats, the most critical scenarios are identified respectively. Studies of bridge protection against potential attacks by using Carbon Fibre Reinforced Polymer (CFRP) strengthening are also discussed. Numerical results in this study provide bridge owners and engineers with thorough and important information on the structural performance of highway bridges under blast loads, helping them in choosing effective protection strategies for possible potential explosion events.
Robustness Assessment of Building Structures under Explosion
Over the past decade, much research has focused on the behaviour of structures following the failure of a key structural component. Particular attention has been given to sudden column loss, though questions remain as to whether this event-independent scenario is relevant to actual extreme events such as explosion. Few studies have been conducted to assess the performance of floor slabs above a failed column, and the computational tools used have not been validated against experimental results. The research program presented in this paper investigates the adequacy of sudden column loss as an idealisation of local damage caused by realistic explosion events, and extends prior work by combining the development of accurate computational models with large-scale testing of a typical floor system in a prototypical steel-framed structure. The floor system consists of corrugated decking topped by a lightly reinforced concrete slab that is connected to the floor beams through shear studs. The design is consistent with typical building practices in the US. The first test has been completed, and subsequent tests are
Evaluation of the Effect of Explosion on the Concrete Bridge Deck Using LS-DYNA
International Review of Civil Engineering (IRECE), 2021
Due to serious damage of concrete structures caused by natural hazards and accidents, evaluating dynamic response of these structures is one of the most important objectives in the field of engineering. In this article, a case study is carried out in order to understand influences of blast load on a concrete bridge. In order to do so, 3D Finite Element Method (FEM) has been used to assess the dynamic response of the bridge and the failure zone for the detonation a of different amount of TNT, on the bridge deck. The results indicate that detonation of 1630 kg TNT causes 12 meters’ failure on the bridge deck. This amount of destruction is twofold greater than the failure occurred during the explosion of 1000 kg TNT. It can be expressed as follows: when the amount of TNT increases by 39%, the destruction of the bridge deck will increase by 100%.
It is important to protect critical buildings (shopping centres, government buildings and embassies), infrastructure and utilities, train and underground stations against being damaged, destroyed or disrupted by deliberate acts of terrorism, criminal activity and malicious behaviour. Normal regulations and building guidelines do not generally take into account these threats. The introduction of regulations or guidelines should support the resilience of the buildings and infrastructure against explosive incidents. In order to protect the infrastructure, methods are required to quantify the resistance of structural elements against explosive loading and to assess the hazards resulting from failure of an element. The applicable state-of-the-art techniques may be either experimental or numerical methods, or a combination of both. Therefore, the thematic group (TG) on the resistance of structures to explosion effects was formed in order to bring the required expertise together, make it c...
The state of the art of explosive loads characterisation
This paper presents the state of the art of characterisation of explosive loads of engineering structures. In recent years, high explosive devices have become the weapon of choice for the majority of terrorist attacks. Such factors as the accessibility of information on the construction of bomb devices, relative ease of manufacturing, mobility and portability, coupled with significant property damage and injuries, are responsible for significant increase in bomb attacks all over the world. In most of cases, structural damage and the glass hazard have been major contributors to death and injury for the targeted buildings. Following the events of September 11, 2001, the so-called "icon buildings" are perceived to be attractive targets for possible terrorist attacks. Research into methods for protecting civilian buildings against such bomb attacks has been initiated. Several analysis methods available to predict the loads from a high explosive blast on buildings in complex city geometries are examined. Analytical and numerical techniques are presented and the results obtained by different methods are compared. Results of the numerical simulations presented in this paper for multiple buildings in an urban environment have demonstrated the importance of accounting for adjacent structures when determining the blast loads on buildings.
Vulnerability Assessment of Steel Bridges Due to On-Deck Blasts
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Highway bridges are a critical element in the infrastructure for personal transportation and movement of goods, yet they are constantly exposed to a number of impacts and risks. One of these possible threats is an accidental or intentional explosion on top of the bridge deck. In this thesis, the effects of deterioration (in the form of section loss) of the superstructure subjected to a blast load are analyzed for an example bridge. The software ABAQUS and its CONWEP model were utilized to run a different scenarios of section thicknesses reductions of the steel elements, varying thicknesses of the concrete slab deck and the locations of the blast source. The analysis output suggests that, for the blast load assumed in this thesis, only small parts of the concrete deck structurally fail while the rest of the bridge remains intact but permanently deformed in a way that a replacement of the bridge superstructure after the explosion appears to be inevitable. Increasing section loss obvio...
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.
IABSE Congress, Nanjing 2022: Bridges and Structures: Connection, Integration and Harmonisation
Terrorist attacks have nowadays become an important issue for the structural design of constructions such as bridges. Indeed, during the last decades, the increase in the number of terrorist attacks has resulted in the loss of many human lives and socio-economic impact on our society. The aims of this research consist in a series of preliminary analyses in view of a study of the effects of an explosion on a long-span suspension bridge. As a suspension bridge was considered the project of the bridge over the Strait of Messina, having as main span of 3300 meters. The structure was modeled using ABAQUS/Explicit software using beams-type 3D finite element modeling. The objectives of the research are double. The first one is the study of the pressures generated by an explosive charge to model the phenomenon during numerical simulations while, the second objective, is to test different discretizations to have a reliable numerical response.