Advanced Materials Research Vols. 255-260

Abstract: Based on experimental research, the bearing performance of the new column (steel tube-reinforced concrete composite columns combination strengthened with angle steel and CFRP) has been studied in detail by finite element method. A finite element model is established based on a series of assumption. The load-displacement curves are obtained. The influence of steel ratio and thickness of CFRP layers to the bearing capacity is analyzed too. The result shows that both the steel ratio and the thickness of CFRP layers have great contribution to the axial load capacity. The finite element analysis results and theoretical analysis which are in good agreement show that simulation results are generally right.

Abstract: The pre-stressed friction loss formula in bending channel recommended by Bridge Rules was based on the uniform distribution hypothesis of contact pressure. From some conflicts in application of the formula, the non-uniform distribution law of the contact pressure was revealed. On the basis of elastic contact analysis, two types of non-uniform distribution hypothesis were proposed, including cosine and second-degree parabola distribution. Then the contact positive pressure expressions were derived respectively and the frictional resistance was calculated to compare with the calculated value under the uniform distribution. The results indicate that the friction resistance under any non-uniform distribution of positive pressure is less than under the uniform distribution. So the uniform distribution assumption of contact pressure does not cause Bridge Specifications formula underestimate friction loss. It is necessary to do further research on the applicability of Coulomb’s law under the contact conditions in the curved channel.

Abstract: Rehabilitation of existing structures with fiber reinforced plastics (FRP) has been growing in popularity because they offer superior performance in terms of resistance to corrosion and high stiffness-to-weight ratio. This paper presents strain coordination results of (two groups)15 reinforced concrete beams strengthened with different methods including external-bonded and near-surface mounted carbon FRP strip in order to investigate the strain coordination of CFRP and steel rebar of RC beam. Because there is relative slipping between RC beam and CFRP, the strain of CFRP and steel rebar of RC beam satisfies the quasi-plane-hypothesis, that is, the strain of longitudinal fiber that parallels to the neutral axis of plated beam within the scope of effective height (h₀) of the cross section is in direct proportion to the distance from the fiber to the neutral axis, the strain of FRP and steel rebar satisfies the equation: , the value of is equal to 1.1~1.3 according to the test results.

Abstract: Deviation rectification of buildings is an arduous task because of its technical difficulty and high risk. So far, the theory of deviation rectification and reinforcement is still incomplete and need to further improvement. In order to investigate the mechanism and construction methods of deviation rectification and reinforcement of buildings, first the paper addressed damage status of inclined buildings in a residential area. And then the causes leading to buildings inclining were analyzed in three aspects. Subsequently, the key construction technologies of rectification and reinforcement were demonstrated. Next, the mechanism of rectifying process was analyzed, and the formula to calculate the amount of steel pipe pile used for deviation rectification and reinforcement was presented. On the basis of research above, some remarkable conclusions are acquired for the engineering rectification and reinforcement, which provide helpful reference information for the similar building rectification engineering.

Abstract: Chimney is the building which is high but the horizontal cross section is small, so the high altitude work surface is small and difficult to construct, in which the stability of the scaffold and the safety of vertical transport equipment are especially important. For the serious problems arising in the prophase construction of the 50m chimney, double rows steel pipe scaffold was designed outside the chimney, and the vertical transportation uses the external grillage hoisting frame. Reformed the internal existing scaffold into pedestrian passage to separate people and material, and a detailed calculation analysis of the structural members such as scaffold, grillage hoisting frame and other structures was carried out. Large deformation, destabilization and other safety problems of the scaffold, grillage hoisting frame and other structures were not arising during the anaphase construction process, which indicates that the construction technical measures and calculation and analysis results are with important guiding significance to guarantee the smooth of the construction, and also can be referenced by other similar projects.

Abstract: The strengthening technique for the aged RC beam was introduced in this paper. A series of measures were utilized to increase the bond strength between CFRP and aged RC beam. The results of experiment indicate that ultimate bearing capacity of the strengthened RC beam increased almost 46%.

Abstract: The introduction of thin-walled stainless steel in buildings has been increased gradually for ensuring the sustainability thanks to excellent corrosion resistance and durability. Many studies on structural behaviors of stainless steel bolted connection fabricated with plane plate have been carried out. This paper is aimed at investigating the ultimate behaviors such as ultimate strength, fracture mode and out of plane deformation(i.e. curling) of channel bolted connection of cold-formed austenitic stainless steel with four bolts (2×2 bolt arrangement). End distance parallel to the direction of applied force is adopted as main variables. Specimens are planned with block shear fracture in ultimate state. In case of bolted connections with a long end distance, curling has also been observed. Ultimate strengths by test results are compared with those of current ASCE design specification and the influence of curling on ultimate strength is discussed.

Abstract: A variety of parametric studies utilizing the finite element analysis (FEA) have been performed by Kim et al in order to predict the mechanical behavior(ultimate strength) of single shear bolted joints in cold-formed(thin-walled) stainless steel. The precedent researches have been conducted with respect to the mechanical behaviors of single shear bolted joints fabricated with four bolts and two bolts. Subsequently, this study has been focused on the comparison of ultimate behaviors between the existing test results and FEA results. In addition, parametric study has been performed in order to investigate the influence of mesh size and washer existence on ultimate behaviors. Therefore, reasonable finite element modelling method and condition were recommended in this paper.

Abstract: Efficiency and stability of forward problem are important in structural optimum design. A real-time algorithm, called inversion reduced-basis method (IRBM), is applied to solve the forward problem in this paper. IRBM is introduced theoretically. Taking a truck frame as an example, results computed from IRBM are obtained. In the optimization process, a modified micro-genetic algorithm (μGA) is adopted to get the global optimum. In the structural reanalysis, IRBM is used, which greatly shorten the design cycle and improve work efficiency.

Abstract: A direct strut-and-tie model to calculate the ultimate shear strength of structural walls based on an interactive mechanical model (C.Y.Tang et al.) is presented. Two common failure modes, namely, diagonal splitting and concrete crushing, are examined in this paper. Ultimate shear strengths of structural walls are governed by both the transverse tensile stresses perpendicular to the diagonal strut, and the compressive stresses in the diagonal strut. Such proposed model is verified aganist three experimental case studies of structural walls. Generally, predictions by the proposed model are not only accurate and consistent in each case study, but also conservative.