In many seismically active regions of the world there are large numbers of masonry buildings. Most of these buildings have not been designed for seismic loads. Recent earthquakes have shown that many of these building...In many seismically active regions of the world there are large numbers of masonry buildings. Most of these buildings have not been designed for seismic loads. Recent earthquakes have shown that many of these buildings are seismically vulnerable and should be considered for retrofitting. Different conventional and unconventional retrofitting techniques are available to increase the strength and/or ductility of unreinforced masonry （URM） walls. This paper reviews and discusses seismic retrofitting of masonry walls with emphasis on the conventional techniques. Retrofitting procedures are discussed with regard to a case study： a stone masonry building in lrpinia region, damaged by the 1980 earthquake. The interventions are evaluated by means of finite elements with a macroelement obtained with a homogenization technique. Linear and nonlinear procedures are compared, and peculiarities of each procedure are shown.展开更多
To evaluate the effect of treating long cracks with the impact crack-closure retrofit(ICR)technique,three rib-to-deck welded specimens with a crack length of about 100 mm were tested.The metallographic structure,crack...To evaluate the effect of treating long cracks with the impact crack-closure retrofit(ICR)technique,three rib-to-deck welded specimens with a crack length of about 100 mm were tested.The metallographic structure,crack section,crack propagation life,and stress variation were analyzed.Finite-element models were also developed,and some optimal values of certain parameters are suggested according to the simulated results.The results show that new crack sources are generated on both sides of the ICR-treated region because of the stress distribution.The fatigue lives of cracked specimens with long cracks are significantly improved by the technique.Considerable residual compressive stress is also induced,and so it is suggested that the optimal impact angle to be applied to real bridges should be 70°.The stress at the weld root is distributed uniformly with the crack closed,and the optimal crack-closure depth is 4 mm.To evaluate the effect of different crack-closure depths in tests,it is recommended that a hot-spot stress method which is extrapolated by three reference points should be adopted.展开更多
文摘In many seismically active regions of the world there are large numbers of masonry buildings. Most of these buildings have not been designed for seismic loads. Recent earthquakes have shown that many of these buildings are seismically vulnerable and should be considered for retrofitting. Different conventional and unconventional retrofitting techniques are available to increase the strength and/or ductility of unreinforced masonry （URM） walls. This paper reviews and discusses seismic retrofitting of masonry walls with emphasis on the conventional techniques. Retrofitting procedures are discussed with regard to a case study： a stone masonry building in lrpinia region, damaged by the 1980 earthquake. The interventions are evaluated by means of finite elements with a macroelement obtained with a homogenization technique. Linear and nonlinear procedures are compared, and peculiarities of each procedure are shown.
基金Projects(51478163,51678216)supported by the National Natural Science Foundation of ChinaProject(2017Y09)supported by the Transport Science Research Project of Jiangsu Province,China
文摘To evaluate the effect of treating long cracks with the impact crack-closure retrofit(ICR)technique,three rib-to-deck welded specimens with a crack length of about 100 mm were tested.The metallographic structure,crack section,crack propagation life,and stress variation were analyzed.Finite-element models were also developed,and some optimal values of certain parameters are suggested according to the simulated results.The results show that new crack sources are generated on both sides of the ICR-treated region because of the stress distribution.The fatigue lives of cracked specimens with long cracks are significantly improved by the technique.Considerable residual compressive stress is also induced,and so it is suggested that the optimal impact angle to be applied to real bridges should be 70°.The stress at the weld root is distributed uniformly with the crack closed,and the optimal crack-closure depth is 4 mm.To evaluate the effect of different crack-closure depths in tests,it is recommended that a hot-spot stress method which is extrapolated by three reference points should be adopted.
