Mitigation of blast effects on aluminum foam protected masonry walls

Abstract

Abstract：Terrorist attacks using improvised explosive devices (IED) can result in unreinforced masonry (URM) wall collapse. Protecting URM wall from IED attack is very complicated. An effective solution to mitigate blast effects on URM wall is to retrofit URM walls with metallic foam sheets to absorb blast energy. However, mitigation of blast effects on metallic foam protected URM walls is currently in their infancy in the world. In this paper, numerical models are used to simulate the performance of aluminum foam protected URM walls subjected to blast loads. A distinctive model, in which mortar and brick units of masonry are discritized individually, is used to model the performance of masonry and the contact between the masonry and steel face-sheet of aluminum foam is modelled using the interface element model. The aluminum foam is modelled by a nonlinear elastoplastic material model. The material models for masonry, aluminum foam and interface are then coded into a finite element program LS-DYNA3D to perform the numerical calculations of response and damage of aluminum foam protected URM walls under airblast loads. Discussion is made on the effectiveness of the aluminum foam protected system for URM wall against blast loads.Unreinforced masonry (URM) construction is extremely vulnerable to terrorist bomb attacks due to the effects of the powerful pressure wave at the blast front that strikes buildings unevenly and may even travel through passageways, resulting in flying debris that is responsible for most fatalities and injuries. An effective solution to mitigate blast effects on URM construction is to strengthen the masonry using retrofit technologies. However, retrofit URM constructions is currently in their infancy in the world [1,2] . Categories of available masonry retrofit include: conventional installation of exterior steel cladding or exterior concrete wall, and new technologies such as external bonded (EB) FRP plating, metallic foam cladding, sprayed-on polymer and/or a combination of these technologies [3,4] . But limited research has been conducted to investigate retrofit technique to strengthen URM walls against blast loads [5,6] . Therefore, it is urgent to study the behaviours of retrofitted URM walls under blast loads, and develop an efficient mitigating solution to enhance blast resistance of URM construction.Metallic foams have excellent properties that can mitigate the effects of an explosive charge on a structural system. Recently, blast tests on aluminum foam protected RC structural members have been conducted and it was found that aluminum foam is very effective to absorb blast energy and thus effectively protect RC structural members against blast loads [7] . It is believed that aluminum foam is also very effective for protection of URM construction against blast loads. Since field blast tests are very expensive and sometimes not even possible to conduct due to safety and environmental constraints, numerical simulations with validated model provide an alternative method for an extensive ...

Blast Protection of Unreinforced Masonry Walls: A State-of-the-Art Review

“…Aluminum foam is a lightweight solid material retaining a lot of aluminum's original properties such as corrosion resistance and strength. Aluminum foam is a promising retrofit material because of its early onset of plastic deformation which allows it to dissipate blast load energy [23].…”

“…Su et al [23] conducted a finite element analysis on aluminum foam using LS-DYNA. A series of numerical analyses were done with scaled values (see (1)) on unreinforced masonry walls.…”

“…Su et al 's [23] and Aghdamy et al 's [11] finite element analyses show that aluminum foam has the potential to be a new material for resisting blast loading. This makes experimental tests of the material desirable.…”

Exploring the Possibility to Assess and Reduce the Risk Due to Hazardous Materials Transportation by Deploying Roadside Safety Barriers

“…The energy of blast loading can be absorbed by lightweight systems used as sacrificial cladding or, in brief, SC. They can be mounted on the front of a non-sacrificial structure to be protected or serve as a component of a blast wall (Guruprasad and Mukherjee 2000ab;Hanssen et al 2002;Su et al 2008).…”

“…SC is generally designed as a multi-layered structure attached to a non-sacrificial frame (Guruprasad and Mukherjee 2000ab;Hanssen et al 2002;Su et al 2008;Ma and Ye 2007). A building wall to be protected by SC serves as a typical support.…”