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In this paper, the effect of cyclic loading on punching strength of flat slabs strengthened with Carbon Fiber Reinforced Polymer (CFRP) sheets is studied. Experimental results of ten slab specimens under monotonic and cyclic loading are analyzed. Eight specimens were strengthened with CFRP sheets on the tensile face of the slabs and the two other specimens were kept un-strengthened as control specimens. The width of CFRP sheets varied in different specimens. After the tests, the punching shear strength of specimens under cyclic loading was compared with those with monotonic loading. The comparison of results shows that cyclic loading decreases the effect of CFRP sheets on punching shear strengthening. This decrease was more for the specimens with a larger value of reinforcing steel ratio. Therefore, it can be concluded that for specimens with large reinforcing steel ratios, cyclic loading may completely eliminate the effect of CFRP sheets on shear strengthening of slabs.

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The torsional capacity of unreinforced masonry brick buildings is generally inadequate to provide a stable seismic behavior. The

torsional strength is believed to be the most important parameter in earthquake resistance of masonry buildings and the shear

stresses induced in the bed joints of such building’s walls is an important key for design purposes. Brick buildings strengthened

with wire-mesh reinforced concrete overlay are used extensively for building rehabilitation in Iran. Their quick and simple

applications as well as good appearance are the main reasons for the widespread use of such strengthening technique. However,

little attention has been paid to torsional strengthening in terms of both experimental and numerical approach. This paper reports

the response and behavior of two single-story brick masonry buildings having a rigid two-way RC floor diaphragm. Both

specimens were tested under monotonic torsional moment.Numerical work was carried out using non-linear finite element

modeling. Good agreement in terms of torque–twist behavior, and crack patterns was achieved. The unique failure modes of the

specimens were modeled correctly as well. The results demonstrate the effectiveness of reinforced concrete overlay in enhancing

the torsional response of strengthened building. Having evaluated the verification of modeling, an unreinforced brick building

with wall-to-wall vulnerable connections was modeled so that the effect of these connections on torsional performance of brick

building could be studied. Then this building was strengthened with reinforced concrete overlay and the effect of strengthening

on torsional performance of brick buildings with vulnerable connections was predicted numerically.

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In this paper, an experimental study has been conducted on strengthening of reinforced concrete (RC) connections by FRP sheets. The innovation of this research is using narrow grooves on critical regions of connection to increase the adherence of FRP sheets and prevent their early debonding. Therefore, four RC connections were made and tested under a constant axial load on the column and an increasing cyclic load on the beam. The first specimen, as the standard reference specimen, had close tie spacing in ductile regions of beam, column and panel zone based on seismic design provisions, and the second specimen, as the weak reference specimen did not have these conditions in all regions. Two other weak specimens were strengthened using two different strengthening patterns with FRP sheets one by ordinary surface preparation and the other with surface grooving method for installing FRP sheets on the connection. The results showed that ultimate load and ductility of the weak specimen compared to standard specimen decreased 25% and 17%, respectively. The shear failure and concrete crushing were prevented in the ductile regions of the beam and panel zone in both strengthened specimens. Also, it was observed that early debonding of FRP sheets was prevented in the strengthened connection with grooving pattern and so had desirable ductility and bearing capacity similar to the standard specimen.