Explosions, Abnormal Loads on Structures (original) (raw)

Protective Design Of Concrete Buildings Under Blast Loading

Sustainability, 2002

Designing buildings to resist failure due to blast loads is an extremely complex procedure. His a process that has been investigated for many years, yet it warrants tluther research. Several issues related to the design of concrete structures to survive blast loads are discussed in this paper. General design issues of “terroristproof’ buildings show how the threat of harrnfil blasts is affecting the thought process in designing government and public buildings as well as international and high-visibility organizations. Understanding the loads produced by explosions is an integral part of dealing with blast-resistant design. Case studies of buildings subjected to blasts reveal how actual structures have handled the dynamic loads. Current research on the subject is also reviewed.

Analysis of Concrete Wall under Blast Loading

2016

The terrorist attacks and threats are the growing problem all over the world that not only affect the life of human being but also affect the structure integrity and its resistance. Explosive devices, human bomb and the other bomb equipments are the major weapon choices for these attacks, significantly threatens civilians and military personnel. As we know that ceasefire and bombing activities are increasing day by day also the terrorist attacks on major buildings can cause catastrophic failure on the building's external and internal structural frames, collapsing of walls and shutting down of critical lifesafety system. Because of all these threat from such extreme condition, effort has been made from the last few decades to find suitable method of structural analysis and design to resist blast load. Detail understanding is required about the blast phenomena and the propagation of waves towards the structure and also response of structure against such shock waves. This paper presents a comprehensive study of concrete wall against this dynamic loading. Concrete wall subjected to blast loading is modeled in Finite Element package Ansys and then analyzed in Autodyn with and without steel plate to study the impact of blast loading.

Mitigation of Blast Load and Protective Design of Vulnerable Buildings with Concrete Facades

Society of Structural Engineers, Sri Lanka, 2020

Attention to design secure buildings against blast loading has become more important as the number of terrorist attacks are increasing daily. Protection of the vulnerable structures against blast loading is a prerequisite to safeguard the occupants' lives. In this background, designing structures with concrete facades to transfer blast induced substantial lateral loads to a moment carrying frame system, and allowing it to behave in the predetermined manner is paramount. A property of designed facade restricts blast waves to propagate into the building and thereby prevents damages to key elements. Further it would avoid the entering of exploded fragments which could injure occupants of the building. Failure of critical/key structural elements will lead to the progressive collapse of the structure. This paper discusses the behaviour of the concrete facades under blast loads; enhancement of load carrying capacity & effective load distribution of facades by introduction of concrete fins and reinforcement design. Procedures to be followed in calculating blast loads, recognition of material nonlinearity for economising the designs and material strength enhancement at straining are also discussed in the paper. In addition, behaviour of structures for different occupancy levels based on performance-based designs are elaborated with relevant to the blast load actions

Structural Analysis of Blast Resistant Buildings

The objective of this study is to shed light on blast resistant building design theories. The general aspects of explosion process have been presented to clarify the effects of explosives on buildings. The main aim of this work is to compare the responses of the structure having shear wall and the structure having braces. Thus, analysing which structure is more blast resistant. Blast loads of explosives weighing 150kg and 250kg is subjected on both the models at distances 25m & 50m. Responses of both the models are observed.

A STUDY ON THE IMPACT OF BLAST LOADING FOR NUCLEAR EXPLOSION ON STRUCTURES

In today's geopolitical environment, the need to protect both military facilities and civilian population from enemy attack has not diminished. Furthermore, we noted an increasing need to protect civilian populations against terrorism and social and subversive unrest. Protecting society against this form of featureless evolving type of warfare will remain a challenge, at least through the first half of 21st century and certainly longer. Any outstanding recognition will require a well planned multi-layered contribute to that strikes a fine coordination between ensuring a nations security and support the freedoms that modern society enjoys. In this context, this project is done to study the impact of blast loading for nuclear explosion on buildings. On high these recommendations define the structural strength pre-eminent to withstand the force produced by a surface burst of a nuclear weapon. A brief forum of the major parameters which exercise the force acting on a structure is followed by a specification of the peak magnitude and time variation of these forces. Specific details which define the net forces acting on an element of the basic structural types are given. As this design requires a sound background on blast loading mitigations and as it not economical only. Following the discussion of the effects of the size and function of a structure is specification of basic properties of reinforced concrete and steel. The protective structural analysis is based upon the Tri Service Manual TM 5-1300, ASCE Manual 42, FEMA guidelines and Indian Standards

Guidelines for Design of Protective Structures Subjected To Unconfined Explosions

In recent times, terrorist attacks are happening at major locations that pose significant threat to human life and infrastructure. The terrorist attack, especially the bomb explosion, causes catastrophic damage on structures, leading to loss of life and damage to assets. Thus, protection of structures against such extreme events or loading conditions is of prime importance. The loss of life and damage of the structure can be minimized by implementing suitable mitigation measures in both structural and non-structural design. The objective of this paper is to discuss on the guidelines for analysis and design of structural components of protective structures against blast pressure for an unconfined explosion. This paper covers in detail about the protection categories, risk assessment, Level of protection and damage, blast phenomenon and methods to predicting blast pressure, dynamic analysis, design and detailing.

Behaviour of Reinforced Concrete Building Frame Subjected to Different Types of Blast Loading

Indian Journal of Science and Technology, 2016

Objectives: To assess the behaviour of reinforced concrete building frames under different types of blast loads. Methods: The method adopted for the analysis was ConWep blast load method. This is a computational method and is based on collection of conventional weapon effects calculations developed by U.S Dept. of Army 1998. The finite element modelling of the building was carried out by using the standard hydrocode software LS_DYNA_971 R 7.1. The charge weight was considered as 226.8 kg of TNT explosive. Findings: Building structures are constructed throughout the world in accordance with building codes. The available codes lack substantial design considerations to prevent or minimize the impact caused by any sort of blast. The attacks by terrorists mainly focus on the iconic buildings like school buildings, government offices and hospitals etc. which affects the safety of the structure and causes loss of lives. So before the design it is required to know the behaviour of the entire building and its critical elements to design to resists the blast loads. In this study, the material models used for the representation of concrete and steel are CSCM_CONCRETE and PIECEWISE_LINEAR_ PLASTICITY respectively. The details of the modelling of building and its progressive collapse, material properties are also discussed. Improvements: The codes which are available for blast design are not provided the different types of failure conditions, for this reason this study was conducted and the failure conditions are observed.

Analytical Investigation of High rise Building under Blast Loading.pdf

This paper presents the dynamic response of high rise building subjected to blast loading. It is about understanding the explosion phenomena and investigating the dynamic response of a concrete frame structure by using SAP2000. Building is of 10 storey is exposed to 30kg TNT and 60kg TNT with three different standoff distances of 10m, 12.5m and 15m respectively. A non-linear three Dimensional is used for analyzing the dynamic response of a structure. In the present scenario, structures under blast loading (i.e. bomb explosion) are acting in short duration with high pressure intensity of shock wave which is outlined in section of TM-5 1300.The aim of this paper is to investigate the performance of high rise buildings under blast loading, blast phenomena and dynamic response of a concrete frame structure under blast loading by using SAP2000 software. Blasting vibration responses are simulated by using MATLAB program. The result obtained in terms of time history function, displacements and influence of the parameter considering the resistance of structure. Therefore, for decreasing the facade on surrounding buildings, moderate explosive energy is used to control the structural damages due to explosion.

Response of Reinforced Concrete Frame Structures under Blast Loading

Procedia Engineering, 2017

Explosions near buildings can cause catastrophic damages and can cause injuries and loss of life to the occupants of these buildings. Experiments on explosions can be very expensive, dangerous and time consuming compared to simulation using suitable software. This study aims at modeling and analyzing a reinforced concrete structure under blast loading using finite element software LS-DYNA. The verification of the developed model was carried out by comparing the results of deflection and spalling with those obtained by reliable field experimental tests. The verification process indicated a close agreement between the obtained results of the model and those obtained from the actual experiments. The material models of concrete and steel were carefully chosen to represent the actual behavior of both materials. The concrete and the steel reinforcement were modeled using LS-DYNA software as solid elements. Concrete was modeled using a continuous cap material model. The steel rebar was modeled using a material model with plastic deformation and strain rate effects. The penalty method was used for linking the concrete and the steel reinforcement joints. The blast was modeled using an empirical method that yielded a very good results. The developed model was utilized to study the effect of blast loading on a square 3 m single story building, where the blast was located in the middle of the building and 1 m away of the building side. The model was analyzed for 2 milliseconds. The effect of increasing concrete strength was studied. The effect of changing the blast location on the behavior of the structure was also investigated.

Analysis of Blast Loading Effect on High Rise Buildings

This paper presents the dynamic response of a High Rise Structure subjected to blast load. The fundamentals of blast hazards and the interaction of blast waves with structures are examined in this study it is about the lateral stability of a high rise building modeled using SAP2000. The model building was subjected to two different charge weights of 800lbs and 1600lbs TNT at a two different standoff distances of 5m and 10m.The blast loads are calculated using the methods outlined in section 5 of TM5-1300 and a nonlinear modal analysis is used for the analysis of the dynamic load of the blast. The primary performance parameters that will be used to evaluate the behavior of the building from a global perspective are the total drift and the inter-storey drift. They are good indicators of nonstructural damage, collapse and ability of the structure to resist P-delta effect. Behavior of R.C frame and concrete infill frame will be computed in Dynamic condition 1. Introduction In the past few years, a structure subjected to blast load gained importance due to accidental events or natural events. Generally conventional structures are not designed for blast load due to the reason that the magnitude of load caused by blast is huge and, the cost of design and construction is very high. As a result, the structure is susceptible to damage from blast load. Recent past blast incidents in the country trigger the minds of developers, architects and engineers to find solutions to protect the occupants and structures from blast disasters Special attention has been given to explosive loads on landmark structures, such as high rise buildings in metropolitan cities, The explosion of bombs in and around buildings can cause catastrophic impacts on the structural integrity of the building, such as damage to the external and internal structural frames and collapse of walls. Moreover, loss of life can result from the collapse of the structure. Understanding the performance of high-rise buildings under explosion is of great importance to provide buildings which eliminate or minimize damage to building and property in the event of explosion. The analysis and design of blast resistant structures require a detailed understanding of explosives, blast phenomena and blast effects on buildings.