Deformation capacity of unreinforced masonry walls subjected to in-plane loading: a state-of-the-art review

Abstract

Rehabilitation of weak and damaged structures has been considered widely during recent years. A relatively modern way of strengthening concrete components is to confine parts under tension and shear by means of carbon fiber reinforce polymer (CFRP). This way of strengthening due to the conditions of composite materials such as light weight, linear elastic behavior until failure point, high tensile strength, high elastic modulus, resistance against corrosion, and high fatigue resistance has become so common. During structural strengthening by means of not pre-stressed FRP materials, usually, it is not possible to benefit from the maximum capacity of FRP materials. In addition, sometimes, the expensive cost of such materials will not make a suitable balance between rates of strengthening and consuming spending. Thus, pre-stressing CFRP materials has an undeniable role in the effective use of materials. In the current research, general procedure of simulation using finiteelement method (FEM) by means of the numerical package ABAQUS has been presented. In this article, 12 reinforced concrete (RC) models in two states (strengthened with simple and pre-stressed CFRP) under cycling loading have been considered. A parametric study has been carried out in this research on the effects of parameters such as CFRP surface area, percentage of tensile steel rebar and pre-stressing stress on ultimate load carrying capacity (ULCC), stiffness, and the ability of depreciation energy for the samples. In the current article also, for design parameters, percentages of tensile steel rebars, surface area of CFPR sheets, and the effective pre-stressing stress in RC beams retrofitted with pre-stressed CFPR sheets have investigated. In this paper, it was investigated that using different amount of parameters such as steel rebar percentage, CFRP surface area percentage, and CFRP pre-stressing, the resulted ULCC and energy depreciation of the specimens was observed to be increasing and decreasing. Results from examined specimens with optimum steel rebar percentage, CFRP surface area percentage, and CFRP pre-stressing which had the most enhancement on ULCC and energy depreciation are reported in the current article.

In-Plane Shear Performance of Masonry Walls after Strengthening by Two Different FRPs

“…In specimen RWS2 no shear-slip was observed rather the crack propagated in a stepped fashion and travelled all the way to the toe and a faster crushing at the wall toe was observed which caused a rapid decrease in load. This kind of failure in URM wall under shear is reported in a number of papers (Stratford et al 2004;Salmanpour et al 2013;Bosiljkov et al 2003;ElGawady et al 2007 etc).…”

Damage indicators for unreinforced masonry building walls subjected to seismic actions

“…Određivanje ili bolje rečeno, procjenjivanje tačne krutosti veoma je važno, na primjer, za projektovanje zidanih konstrukcija na osnovu metode proračuna, koja se zasniva na deformacijama [12,17]. Histerezna krivapetlja može se koristiti za procjenu deformacionog kapaciteta zidova.…”

“…Determining, or rather estimating the correct stiffness is of the utmost importance, for example for the deformation-based design of masonry structures [12,17]. It is the hysteresis curve that can be used for the estimation of the deformation capacity of masonry.…”

On the Use of CFRP Sheets for the Seismic Retrofitting of Masonry Walls and the Influence of Mechanical Anchorage

“…However, the horizontal loads induced by earthquake loading result in the development of in-plane and out-of-plane forces [2]. Recent work by Salamanpour et al [3] indicates that performance of unreinforced masonry (URM) in structurally-designed low-rise URM buildings may be considered adequate for the category of ordinary buildings even in regions with appreciable seismic hazard. Nevertheless, the recent seismic events of Modena, 2012, Christchurch, 2011, and L'Aquila, 2009 [4][5][6][7][8][9], which not only caused extended material damage but also significant human toll, have critically pointed out the urgent need for appropriate strengthening of existing masonry structures.…”