Advanced Materials Research Vols. 163-167

Abstract: Ceramsite is a typical representation of artificial lightweight aggregates and the new energy saving and soil building materials. It has great prospects for development new material in the field of wall materials innovation and building energy efficiency. Ceramsite prepared from fly ash, coal gangue, sludge and other solid wastes were studied. Its crushing strength was 3.4~13MPa and water absorption was 2.0% ~ 18.0%, which are consistent with national performance targets. And we discussed ceramsite’s main problems in the preparation and application and prospect. To use solid wastes to prepare ceramsite can provide a new space for resource utilization and has better social environment and economic benefits.

Abstract: A mathematic model for semi-rigid joint frame is proposed, in which, both the moment-rotation and shearing-deformation characteristics of joint are taken into account. For element with simi-rigid joints, the stiffness matrix is derived, and some equivalent nodal force vectors are obtained when the element is subjected to different loads. The internal force distribution and the deformation in structure are greatly affected by the moment-rotation and shearing-deformation relationships of joints.

Abstract: The section of the column under axial compression used in a certain electrostatic precipitator is composed of double H shaped steel limbs and the stiffened connecting web by weld. As the width of connecting web usually exceeds 3 times of the section height of H shaped steel, the axis which connecting web lies in is the weaker axis for the stiffness of column section, while the midperpendicular of connecting web is the stronger axis. In consideration of initial geometrical imperfections and weld residual stresses, the study on stability round the stronger axis of column subjected to axial compression by nonlinear finite element method is conducted. The research results indicate that the column doesn’t present the flexural buckling round the stronger axis, but present the elasto-plastic flexural-torsional buckling. A buckling factor is produced to measure the stability performance of column round stronger axis. When the connecting channel shaped steels between two limbs and the stiffeners located on connecting web are strengthened, the buckling factor increases slightly. When the width-thickness ratio of connecting web increases, the buckling factor decreases significantly. When the slenderness of H shaped steel round the stronger axis is kept constant and the height-thickness ratio of H-shaped steel web increases, the buckling factor increases. Based on a great many computation results, the regressed recommendation is proposed how to evaluate the design buckling bearing capacity of column under axial compression round stronger axis.

Abstract: Both total potential energy and buckling equation of two-span continuous beam with lateral elastic brace under uniform load are deduced, based on energy variation method and the principle of minimum potential energy. Buckling of H-beams is simulated by ANSYS software, then compared to theoretical value, validated its rationality. High precision buckling moment formula is regressed using 1stOpt which is a famous mathematical optimization analysis software in China. The relationship between lateral brace stiffness and buckling moment is obtained. Results: with lateral brace stiffness increases, critical bending moment of beam increases within up-limit, e.g. when lateral brace stiffness increases to certain extent, buckling moment no longer increases.

Abstract: Based on Dongting Hu three-tower cable-stayed bridge on high-speed railway, stiffness ratio of middle tower to side tower (SROMTTST), vertical bending resistance stiffness (VBRS) of girder, height of tower, area of cable were studied by using FEM. The results show that the structure is more economical on condition of the SROMTTST less than 3.0. With the increase of VBRS of girder, the tensile forces of the cables near mid span increase and decrease near towers. Meanwhile, both the moments of the tower and the deflection of the girder get smaller. The ratio of tower height to span (ROTHTS) has great influence on the bridge rigidity. Every 0.01 increase of the ROTHTS can decrease a ratio of deflection to span (RODTS) about by 3%～5%.

Abstract: 18 specimens of cold-formed steel three limbs built-up section members are tested under axial compression load in this paper. The section forms are divided into two categories: A and B. Load-displacement (P-Δ) curves and failure characteristics of specimens are obtained. The results show that: As to section A members, the failure characteristics of LC, MC and SC series of specimens are flexural-torsional buckling, torsional buckling and distortional buckling, local buckling and distortional buckling. As to section B members, the failure characteristics of LC, MC series of specimens are flexural buckling, while local buckling and distortional buckling for members of SC series.

Abstract: As a limit analysis method lately presented, the elastic modulus reduction method (EMRM) has the advantages of simplicity and high efficiency. In this paper, the strategy of elastic modulus adjustment of the EMRM is studied in order to extend the method applicable to the limit analysis of structures containing flaws (SCF). Two new algorithms of the reference element bearing ratio, reference element bearing ratio based on reference stress (REBS) and reference element bearing ratio based on integral element bearing ratio gradient (REBG), are proposed. Numerical examples show that the problems of instability and non-convergence in iterative process of limit analysis of SCF are improved, when the REBS or REBG is used in the strategy of elastic modulus adjustment of the EMRM.

Abstract: The temperature field of a 600MW supercritical boiler water-wall in burner zone is calculated based on finite-element method. Bilinear quadrilateral is used in meshing. Flux rate of the fire-facing side is calculated in section. The work condition of working medium is determined based on inlet medium and outlet medium. And heat transfer coefficient is defined. Temperature field in different working conditions is calculated to analyse the safety of the boiler.

Abstract: Four groups (12 in total) of welded hollow spherical joints with ribbed stiffener were tested under uniaxial loads in this paper. With the adoption of elasto-plastic model and consideration of geometric and material nonlinearity, the whole loading process of the specimens was simulated by ABAQUS. Through combining the test data and computing results, two recommendations used to quantitatively determine the ultimate failure load of spherical joint in test are proposed. The relationships between bearing capacity and various influence factors, which include the thickness and diameter of hollow sphere, diameter of steel tube are analyzed and illustrated at the end of this paper.

Abstract: The profiled steel structure of cold-formed square steel tubular has better seismic behavior and is suitable for reconstruction in seismic disastrous area. The joint is the key to the design of structure, so it needs further research on the mechanical properties. Using finite element software ANSYS to analysis two kinds of welding joints which under monotonic loading, the results show that: (1)The ultimate bearing capacity and yield load of improved joints greatly enhanced compared to conventional joints, and the plastic hinge moved to outward from the beam and column interface. (2)Until loading to the yield load, the improved joints has longer yield platform and better ductility. (3)The axial compression ratio has stronger effect on the conventional joints than improved joints on bearing capacity and initial stiffness.(4)Until loading to the ultimate load, degree of stress concentration on the improved joints is less than conventional joints, and the plastic hinge moved to outward, avoid brittle fracture of the joint.