This paper references the structural design of the novel oblique frame-grid multi-ribbed composite (MRC) wall in studying the seismic performance of frame-supported MRC (FSMRC) walls. Two 1/2-scale FSMRC wall specimens with first floors composed of frame-shear walls and second floors composed of MRC walls were tested under cyclic loading. The failure processes and force-transfer mechanisms of both the orthogonal and the oblique frame-grid specimens were then investigated. Concurrently, the hysteresis of the vertex-horizontal displacement and inter-storey displacement, the skeleton curves, the loading-strain curves of the reinforcing bars of the members, and the residual deformation ratios of the specimens were analysed. The results indicate that the FSMRC wall exhibited good seismic performance and that the oblique frame-grid design was able to improve the overall ductility, deformation capacity, seismic resistance and repairability of the wall.
A building structure comprising a prefabricated lightweight concrete-filled steel tubular (CFST) framework composite slab structure is proposed. Five full-scale specimens (i.e., one empty framework and four-walled frameworks) were tested under reversed cyclic loading to study their earthquake-resistance performance. Of the four wall specimens, three were walled using composite slabs, one had no openings, one had a window opening, and one had a door opening. One was walled with a concealed steel-truss slab. A comparative study on the strength, stiffness, ductility, hysteresis characteristics, and dissipated energy of the specimens was performed. The working mechanism of the framework and slab was then analyzed. The results show that, if reasonably assembled and connected, the framework and slab work in a well-coordinated manner. The walled framework had greater lateral load-bearing capacity, better energy-dissipation, greater stiffness reduction, and better deformability than an empty framework. The area and type of slab opening had a significant impact on structural performance because a door or window opening contributed to a smaller lateral load-bearing capacity and initial secant stiffness of the structure. However, this had no clear impact on the accumulative dissipated energy of the structure.
Abstract:In this paper, we carry out low-reversed cyclic loading tests on differently-structured frame-supported concealed multi-ribbed wall panels with energy-efficient blocks. Models for evaluating damage performance are introduced for comparative study, in an effort to identify the preferable model for such a structure. To this end, the paper uses OpenSees, a nonlinear finite element software that can accurately depict the mechanical performance of a structure, both to calculate the necessary mechanical parameters and to verify the damage model of interest. In this paper, we determine the numerical ranges for the damage index at different stages of accumulative damage, attaching detailed descriptions on a stage-by-stage basis. Then, we offer suggestions for structure restoration according to these indices.
As part of the search for a seismic isolator for low-rise buildings, this paper proposes a marble-graphite slide seismic isolation system composed of marble-graphite slides, an upper foundation beam, the lower counterpart of the upper beam, and the corresponding stop blocks, with the stop blocks consisting of restrictive screws, positioning plates, nut connectors and stop holes linking the two foundation beams. To provide the desired isolation performance, plain mortar bars can be included at the beam interface to better control the initiating loads for foundation slippage. Tests of low-reversed cyclic loading were performed on four different masonry specimens: a recycled brick wall, a clay brick wall, an integrated recycled brick wall with flay ash blocks sandwiched between, and its clay brick counterpart. The four specimens were provided with marble-graphite slide isolators placed at the foundations. The isolator thickness was 20 mm, and the graphite and the marble served as a lubricant and a bearing, respectively. This paper then analyses all of the specimens in terms of the damage that occurred, the initiating load for slippage, the hysteretic performance, the bearing capacity and the performance of the stop blocks. The results indicate that mortar bars embedded in the marble-graphite slide isolator offer effective control of the initiating load, and the isolation system delivers good hysteretic performance. The stop blocks are capable of withstanding a large-magnitude earthquake and are a good choice for constraining the slippage displacement. Damage or failure of the specimens occurs only when the low-reversed cyclic loading continues after slippage takes place. The design is shown to be an outstanding and flexible seismic scheme for use in low-rise buildings.
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