Analytical study of reinforced concrete slabs with ferrocement under blast load

Authors
K. Nasserasadi
A. tajvar
J. moradlou
Abstract
Reduction of social and financial losses and rehabilitation in important buildings as a result of terrorist attacks and accidental blast is vital. In this regards, using concrete slabs as a protective shield is one of the main methods of protection. Currently, many methods have been used for improve the behavior of this element such as FRP sheets, fibers, high strength concrete and composite concretes. Using these methods is not favorable due to several reasons such as: increase the dead load of structure, increase the cost of project, employ high-tech methodology and needed high skilled worker for implementation. Therefore, for ordinary projects and households, these methods may not cost effective and a simple and more cost effective method needed to be implemented. In this paper, the behavior of RC slabs reinforced with steel wire mesh which is easy to implement and cheap was studied analytically under blast loads. To this goal, effect of different parameters such as number of wire meshes, slab thickness and concrete strength on maximum slab displacement, damage areas and performance of slabs were studied numerically. First the model was built in general FEM software and calibrated to existing experimental and analytical studies. Then numerous slabs with different thickness (40, 60 and 80 mm), concrete strength (30, 40 and 50 MP), different layers of wire mesh (0, 1, 2, 3) where considered and analyzed with a general FEM software. The results have shown that increasing of slab thickness, concrete strength and adding different layers of wire mesh reduces the slab displacement and the damage area. Due to higher damage in thin slabs (4 Cm) and low concrete strength (30 MP), the effect of adding wire were higher. Generally, the slab thickness is the most important parameter in controlling the damage in the salbs under blast load, but increasing the concerete strength and adding different layer of wire mesh, reduced this damages. From the viewpoint of slab performance, which is defined by the amount of displacement and plastic rotation of hinges, it is observed that the performance of thicker slabs (60 and 80 mm) were in the life safety or immediate occupancy state which is quite good for ordinary purposes. Using wire improved the performance of these slabs. In the thinner slab (40 mm) the performance of slab with concerete strength of 30 MP, was not satisfy the life-safety requirement, therefore it is needed to improve this performance. The result of analysis were shown that adding different layer of wire mesh improve the performance of the slab and limits that. Although different layer of wire mesh did not have significant effect on improvement of the slab performance, it limits the performance of slabs to the code’s value in several occations. Generally, it can be concluded that adding the wire mesh could reduce the amount of damage to the slabs under blast loads, which was expected results, but this reduction, is not that much significant for many occations. This method is more effective in thin slabs with lower concerete strnght.

Keywords

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Modares Civil Engineering journal
Volume 18, Issue 1
May and June 2018
Pages 31-42