Applied Mechanics and Materials Vols. 166-169

Abstract: A 3-D finite element model (FEM) using ABAQUS was established to simulate the performance of the composite joints with reinforced concrete and steel. Accurate material model, element type, and solution method were discussed in the model. Some composite joints, concrete-filled steel tubular (CFST) column to steel beam, steel tube confined concrete (STCC) column to reinforced concrete (RC) beam and reinforced concrete (RC) column to steel beam were modeled based on the model, respectively. The results from FEM are good agreement with the test results. The mechanism of the composite joint was investigated based on the FEM.

Abstract: The optimization problem of building structure has the technical difficulties of nonlinear, discrete, indifferentiable and nonconvexity character, the traditional algorithm based on MATLAB can not solve practical engineering optimization problem accurately. Based on general genetic algorithm is as the foundation in this paper, the theory basis of modified algorithm is applied based on the application of functional analysis and analyses the genetic algorithm for the iterative characteristics is analyzed, and the three stem rod calculation is verified based on application of functional analysis improved genetic algorithm, which solves the optimized design of common rod technical problem and achieves good calculation accuracy and efficiency.

Abstract: This paper presents symplectic method for the derivation of exact solutions of functionally graded piezoelectric beam with the material properties varying exponentially both along the axial and transverse coordinates. In the approach, the related equations and formulas are developed in terms of dual equations, which can be solved by variables separation and symplectic expansion in Hamiltonian system. To verify advantages of the method, numerical examples of bi-directional functionally piezoelectric beam are discussed.

Abstract: Bond between steel and concrete is surely one of the most important aspects in reinforced concrete (r.c.) structures. The structural behavior in general and the formation of the resistant mechanisms in particular, for r.c. structures depends on bond. Normally bond performance has always been related to the relative rib area; in the recent years, a continuous discussion on code specifications regarding the lowering of the limits for the relative rib area (bond index) is under way. The previous values were based on a wide experimental campaign. In general the latter should guarantee a good level of bond in all the common situations. Moreover building industry increased the use of rebar straightening by means of machines used to straighten and shape rebar in coils for use on construction sites. The straightening produces a damage on the ribs that modifies their geometrical properties, essentially due to the action of the rolling line in which a permanent deformation is induced. In the present work, the experimental results of 60 pull-out tests, carried out according with the RILEM testing method, on ribbed reinforcing bars with different reduced rib profile systematically reproducing the straightening process of coil-reinforcing bar produced are shown. Three different diameters are considered: 8, 12 and 16 mm. The behavior in terms of bond strength response is also compared to the Code provisions and then discussed.

Abstract: In this study, a full-scale lightweight concrete shear wall was tested under monotonic loading, and overall behavior and failure mode of the test specimen was discussed. Results of this study will provide useful information regarding the performance of lightweight concrete shear walls and similar systems subjected to static lateral loads.

Abstract: To investigate the axial compressive behavior of reinforced concrete columns with strong confinement, a total of five full-scale reinforced concrete columns with stirrup characteristic values in the range 0.22~0.47 and section dimension 600mm×600mm were tested under concentric compression loading. The test results indicated that all specimens failed in a similar way. The longitudinal bars buckled in compression; the peripheral stirrups bowed out and several stirrups fractured; the cover concrete in the mid-height section of specimens spalled seriously; however, the core concrete of specimens was not crushed. The axial compressive bearing capacity and deformation ability of reinforced concrete columns could be improved by strong confinement. When specimens reached the ultimate bearing capacity, the longitudinal reinforcement yielded and provided axial bearing capacity for specimens; the transverse reinforcement reached tensile yield strength and provided effective confinement for the core concrete.

Abstract: It is known from previous experiments that the load-carrying capacity for RC slabs at large deflection is governed and enhanced by the tensile membrane action. However, due to the intrinsic complexity of concrete properties, it is hard to capture the history of the load-deflection relationship for RC slabs. After reviewing several analytical reinforced concrete models, the author develops a simplified load-displacement semi-analytical model for laterally unrestrained simply supported RC slabs. Three stages have been identified for this model, which are elastic stage, transition stage and pure tensile membrane action stage. Compared with the existing RC slab tests, the author's model shows good agreement with the previous test results.

Abstract: The in-plane seismic performance has been studied by many researchers all over the world, whereas few studies have been done on the out-of-plane behavior of the infilled RC frames. In this paper, a separate finite element model for simulating the out-of-plane failure mode and capacity of masonry-infilled RC frames is developed using 3-D elements with damage-plasticity material model and the surface-based contact cohesive interaction model simulating the interface between blocks. Comparison between the results of analysis and experiment indicates that the present model can successfully simulate the out-of-plane behavior of the structure.

Abstract: In order to measure attaching performance of the suction fan against a concrete wall, test apparatus measuring suction force of the fan was developed. Using this test apparatus, four types of concrete wall specimens were tested to measure the attaching force. The test apparatus consisted of a fan motor, a pneumatic cylinder, a load cell, and sensors for vacuum pressure and a rotating speed of the fan. Vertical wall surface of concrete material were manufactured to four different shapes that is flat, step, rib and embossing type. When the fan is rotating in the fan-housing which is fixed by metal frame, the wall specimen is moved near to fan-housing edge by the pneumatic cylinder. And the specimen may be attached to fan-housing edge by suction force of the fan, and the wall specimen is reversely moved away from the fan-housing edge by the pneumatic cylinder. Then suction force of the fan was measured using a load cell. And the suction force was measured depending on specimen types and varying the rotation speed of the fan. Test result shows that the fan speed is proportional to the suction force, and interestingly, suction force is almost independent from the specimen shapes. The maximum suction force was equally measured with 231.9 N on the step and embossing type surface with 1,800 rpm.

Abstract: Concrete filled steel tube (CFST) reinforced concrete (CFSTRC) columns subjected to axial compression were experimentally investigated in this paper. A total of ten specimens were tested. The main parameters varied in the experiments were steel tube ratio and concrete strength. It was found that, under axial compression, the column ultimate strength increases with the increasing of steel tube ratio and concrete strength. The work in this paper provides a basis for the further theoretical study on the behavior of CFSTRC columns.