Abstract:The paper presents a technique for retrofitting non-seismically reinforced concrete (RC) masonry-infilled frames with textile-reinforced mortar (TRM) jacketing. In the present study the application of TRM is examined on nearly full-scale, as-built and retrofitted, three-storey frames, subjected to in-plane cyclic loading. The results of testing a 2:3 scale, as-built frame representing typical structures with non-seismic design and detailing characteristics and of a companion frame retrofitted via TRM jacketing are presented and compared in terms of the efficiency of the proposed technique to enhance the strength and deformation characteristics of sub-standard infilled frames.
The effectiveness of RC jacketing or FRP wrapping for seismic retrofitting of rectangular columns having smooth (plain) bars with 180° hooks lap-spliced at floor level is experimentally investigated. The relatively low deformation capacity and energy dissipation of five unretrofitted columns is found not to depend on lap length, if lapping is not less than 15 bar-diameters. Six columns cyclically tested up to ultimate deformation after RC concrete jacketing demonstrate force and deformation capacity and energy dissipation sufficient for earthquake resistance, regardless of the presence or length of lap splicing in the original column. Another ten columns cyclically tested to ultimate deformation after wrapping of the plastic hinge region with CFRP show that FRP wrapping of the splice region is more effective than concrete jackets for enhancement of the deformation and energy dissipation capacity of old-type columns with smooth bars lap-spliced at floor level, provided that wrapping extends over the member length sufficiently to preclude plastic hinging and early member failure outside the FRP-wrapped length of the column.
Abstract:The present paper proposes an analytical approach for modeling the behavior of textilereinforced mortar (TRM)-strengthened masonry-infilled reinforced concrete (RC) frames under seismic loading. The model falls into the discrete diagonal-element type and is based on the use of single-strut and single-tie elements to represent the infill panel. It builds on the results of past experimental studies by the authors in which the application of TRM jacketing was proved to be effective for the seismic retrofitting of masonry infilled RC frames. The model is implemented in the non-linear finite element code Opensees, with the parameters of the diagonal elements being determined from a series of tests on TRM coupons and masonry specimens. Finally, the results of the numerical analyses are compared with the experimental data of cyclic tests on three-story masonry infilled RC frames, as-build and after retrofitting.It is shown that the model developed herein adequately accounts for the TRM-strengthening contribution to the global response of masonry infilled frames.
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