These days the amount of demolished concrete waste has been increasing due to reconstruction and redevelopment of aged buildings. So the use of recycled aggregates is recommended to solve environmental problems. Some investigations have been carried out to study the flexural behavior of reinforced concrete beams with recycled aggregates. But these have some limitation due to the use of low quality recycled aggregates and small-scale specimens in the laboratory. The purpose of this experimental study is to evaluate the flexural behavior of simply supported RC beams subjected to four-point monotonic loading and made with recycled aggregates. Seven full-scale RC beams were manufactured with different replacement level of recycled aggregates. The main parameters of the study are combination of aggregates. From the test results, the flexural behavior of the beam is described in terms of crack patterns and failure modes. And the flexural strength of RC beam with different types of recycled coarse aggregates and recycled fine aggregates is compared with the provision of KCI code.

This paper will describe the experimental results on the shear behaviors of reinforced concrete (RC) beam with recycled coarse aggregate (RCA). The primary objective of this research is to evaluate the influences of different RCA replacement percentage (i.e, 0%, 30%, 60%, and 100%) on the shear performance of reinforced concrete beams without shear reinforcement. Eight large-scale RC beams without shear reinforcement were manufactured and tested to shear failure. All had a rectangular cross-section with 400mm width × 600mm depth and 6000mm length, and were tested with a shear span-to-depth of 5.1. The results showed that the deflection and shear strength were little affected by the different RCA replacement percentage. Actual shear strength of each RCA beam was compared with the shear strength predicted using the provisions of ACI 318 code and Zsutty'e equation for shear design of RC beams. ACI 318 code predicted the shear strength of RCA reinforced concrete beams well.

Unreinforced masonry (URM) buildings that are characterized by brittle, heterogeneous, and anisotropic responses have complex nonlinear dynamic behavior and high vulnerability under seismic loading. While masonry confined by tie‐columns and lintel beams can achieve better ductility and stability, the wall openings induce stress concentration around the corners and diminish the strength. Furthermore, the interacting in‐plane and out‐of‐plane responses of masonry walls could significantly affect the post‐cracking behavior and increase the collapse risk. To attain reliable seismic design of confined masonry buildings with openings, the collapse fragility under bi‐directional seismic loading shall be addressed and thoroughly investigated in this study. Advanced discrete finite element models (DFEM) with coupled damage‐plasticity traction‐separation law, which can simulate complex nonlinear dynamic behavior such as disintegration and progressive collapse, were developed for the masonry structures and validated against experimental results. Four one‐storey residential masonry buildings: (1) unconfined (UCM), (2) confined by tie‐columns at four building corners (CM‐I), (3) confined by toothed tie‐columns (CM‐II), and (4) confined by toothed tie‐columns and lintel beams (CM‐III) were considered. A series of incremental dynamic analyses (IDA) with 15 bi‐directional ground motions and fragility analyses were performed to investigate the dynamic characteristics, base shear, hysteresis behavior, failure mechanism, collapse probability, and exceedance probability for different drift limits were studied in‐depth. CM‐II with toothed tie‐columns had the lowest collapse probability and fragility at different drift limit states. The introduction of lintel beams to CM‐III lead to an increase of the storey‐drift‐based fragility compared to CM‐II, as a result of the increased maximum base shear of CM‐III with higher post‐damage stiffness. The lintel beams also inflicted short‐column effects on the tie‐columns. Nevertheless, the lintel beams could delay the out‐of‐plane collapse of the masonry walls by shortening the effective wall arching length. In some cases, the CM‐III could achieve better performances than CM‐II even in terms of storey drifts. The response variations of CM‐III to the changing of the non‐intensity related ground motion parameters are also lower than CM‐II.

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-Cyclic loading tests for beam-to-column weak-axis connections were performed to investigate the seismic performance. In this study, the connections were developed to improve the constructability on the basis of investigation for existing small-size steel structures. The primary test parameter is the number of high-tension bolts which are used to connect steel beam and column using exterior and interior flange plates. Test results showed that the number of bolts had a significant effect on the cyclic behavior of beam-column weak-axis connections. From the analysis of test results, it is concluded that more than four bolts in the connections can satisfy the requirements of semi-rigid connection presented in current design codes. All of specimens showed the bearing failure around bolt holes and fracture at the beam flange. However, when the web height and the flange width is relatively small, the number of the bolts used in the connections might be limited. Thus, the additional research in this area is needed.