Current Issue : October - December Volume : 2017 Issue Number : 4 Articles : 5 Articles
Three recycled aggregate concrete (RAC) beam-column interior-joint specimens (including two modified recycled aggregate\nconcrete interior joints with replacement of fly ash ratio of 15%) were tested under cyclic loading in order to study the bond behavior\nof the longitudinal steel bar at RAC joint. The tests obtained load-strain hysteresis curves of longitudinal bars. The relative bond\nstrength of longitudinal bar in characteristic stages was calculated.The test results indicated that the longitudinal steel bar in RAC\njoint is able to supply a stable bond stress both in the full crack stage and in the ultimate stage, meaning that the requirements of\nstress transferring and displacement coordinating between RAC and reinforcements can be satisfied. The larger the diameter of\nsteel bar, the more serious the bond strength degradation. The RAC with fly ash can improve the interface compactness and bond\nstrength of recycled aggregate in full crack stage. When beam-column interface of concrete compression zone reaches ultimate\nstrain, the compressive stress of the longitudinal reinforcement cannot be exerted.The bond stress of the steel bar cannot realize\nthe pull and compressive stress conversion in the length of the core area of the joint owing to the stress hysteresis of the compression\nrebars....
This paper presents a new-type of fabricated beam-column connections with end plates.Thejoint details are as follows: the concrete\nbeams are connected to column by end plates and six high strength long bolts passing through the core area. In addition, in order to\nincrease the stiffness and shear strength, stirrups are replaced by the steel plate hoop in the core zone. To examine the fail behavior of\nthe fabricated beam-columnconnection specimens, a quasi-static test is conducted for nine full-scalemodels to obtain the hysteresis\ncurves, skeleton curves, ductility, energy dissipation capacity, and other seismic indicators. The experimental results show that all\nspecimens failed in bending in a malleable way with a beam plastic hinge and the hysteresis curves are excellently plump for the\nend plate connections. From the seismic indexes, the fabricated connection specimens exhibit better seismic performance, which\ncan provide reference for the application of prefabricated frame structure in the earthquake area....
Forensic building is needed to examine the affected building\nstructure components to assess the structural integrity. This paper\nhighlights some of the studies involved on affected concrete structures in\nvarious building types where the non-destructive test (NDT) and\ndestructive tests. The structural integrity can be evaluated based on the\nextent of deterioration from the experimental results for instance the cause\nof the corrode reinforcements was due to inadequate concrete cover,\nwhereas the failure of the concrete wall was due to structures� under design\nwhich leads to the collapse of the wall. The condition of the floor slab that\nexperience vibration was assessed from the Laser Doppler Vibrator test\n(LDV). Based on the test results the peak acceleration of the particular\nfloor slab is higher....
The nonlinear stiffness matrix method was incorporated to investigate the structural performance of steel portal frames with semirigid\nconnections. A portal frame with unstiffened extended end-plate connection was designed to demonstrate the adequacy of\nthe proposed method. Besides, the seismic performance of steel portal frames with semirigid connections was investigated through\ntime history analysis where kinematic hysteresis model was assigned to semirigid connections to account for energy dissipation\nand unloading stiffness. Based on the results of the study, it was found that generally semirigid connections influenced the force\ndistribution which resulted in the decrease in base shear and lighter frame compared to the rigid one. The results also indicated\nthat there was no direct relationship between maximum displacement at the top and connection stiffness in high-rise frames....
Timber platform-frame shear walls are characterized by high ductility and diffuse\nenergy dissipation but limited in-plane shear resistance. A novel lightweight constructive system\ncomposed of steel columns braced with oriented strand board (OSB) panels was conceived and\ntested. Preliminary laboratory tests were performed to study the OSB-to-column connections with\nself-drilling screws. Then, the seismic response of a shear wall was determined performing a\nquasi-static cyclic-loading test of a full-scale specimen. Results presented in this work in terms of\nforce-displacement capacity show that this system confers to shear walls high in-plane strength and\nstiffness with good ductility and dissipative capacity. Therefore, the incorporation of steel columns\nwithin OSB bracing panels results in a strong and stiff platform-frame system with high potential for\nlow- and medium-rise buildings in seismic-prone areas....
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