Yong-Hui Huang

Unified Practical Formulas for Vibration-Based Method of Cable Tension Estimation:

In this paper, unified practical formulas are proposed to estimate cable tension for vibrations under different boundaries. Correction coefficients are applied to the cable tensions calculated from the taut string theory. In these formulas, a dimensionless parameter η is introduced to represent the relative bending stiffness of the cable in lieu of the dimensionless parameter ξ in the previous formulas found in practice. Results have shown that the proposed formulas are accurate. For the fixed-fixed boundaries, the error in the estimated cable tensions for various frequencies is less than 3% for η ≤ 0.88, and less than 1% for η ≤ 0.55. For the fixed-hinged boundaries, the error in the estimated cable tensions for various frequencies is less than 1% for η ≤ 0.9. If there are multiple frequencies in the in-situ measurement, the proposed formulas can be used to identify the cable tension and bending stiffness simultaneously by solving a quadratic equation. The proposed formulas have been validated against several numerical examples as well as practical test cases.

Experimental Study on the Welding Residual Stresses of Integral Joint Using Full-Scale Joint Model of a Steel Truss Bridge:

In order to study the residual stress distribution of the welded integral joint of steel truss bridge, a full-scale model was fabricated with the same welding process, same material as the real bridge in the bridge workshop. The residual stress state and distributions of residual stresses in the full-scale model were measured using blind-hole strain-gage method. The tested results show that high residual stress is caused during the welding process and the maximum tensile residual stress may reach the yield strength of the steel. Longitudinal tensile residual stress appears in the regions near the welding bead and changes to compressive stress at a certain distance from the welding bead, with the maximum tensile residual stress being in the centre of the welding bead. In butt-welding between two plates with different thicknesses, the value of welding residual stress in the thinner plate is lower than that of the thicker one. The results presented in this paper would be useful as references for developing measures of reducing the residual stress of integral joint in the fabrication of a real bridge.

A Method of Reinforcement and Vibration Reduction of Girder Bridges Using Shape Memory Alloy Cables

Bending and torsional vibrations caused by moving vehicle loads are likely to affect the traffic safety and comfort for girder bridges with limited torsional rigidity. This paper studies the use of cables made of shape memory alloy (SMA) as the devices of reinforcement and vibration reduction for girder bridges. The SMA cables are featured by their small volume, expedient installation. To investigate their effect on the vibration of girder bridges, theoretical analysis, numerical simulation and experimental study were conducted in this paper. For bending vibration, the governing equations of the girder with and without SMA cables subjected to moving vehicle loads were derived, while for torsional vibration, the finite element (FE) simulations were used instead. The results of bending and torsional vibrations obtained by the analytical approach and FE simulations, respectively, were compared with the experimental ones from model testing. It was confirmed that the SMA cables can restrain the vibration of the girder bridge effectively.

An Analytical Solution for Lateral Buckling Critical Load Calculation of Leaning-Type Arch Bridge

An analytical solution for lateral buckling critical load of leaning-type arch bridge was presented in this paper. New tangential and radial buckling models of the transverse brace between the main and stable arch ribs are established. Based on the Ritz method, the analytical solution for lateral buckling critical load of the leaning-type arch bridge with different central angles of main arch ribs and leaning arch ribs under different boundary conditions is derived for the first time. Comparison between the analytical results and the FEM calculated results shows that the analytical solution presented in this paper is sufficiently accurate. The parametric analysis results show that the lateral buckling critical load of the arch bridge with fixed boundary conditions is about 1.14 to 1.16 times as large as that of the arch bridge with hinged boundary condition. The lateral buckling critical load increases by approximately 31.5% to 41.2% when stable arch ribs are added, and the critical load increases as the inclined angle of stable arch rib increases. The differences in the center angles of the main arch rib and the stable arch rib have little effect on the lateral buckling critical load.

A proposed model for creep in mass concrete under variable ambient conditions

Abstract The creep characteristic of the concrete used in real structures is different from that of those test specimens in the laboratory because of the remarkable hydration heat resulting in the big bulk and the service condition with varying temperature and relative humidity. A creep model had been proposed to describe the creep characteristic of the massive concrete under the natural climatic variations. The equivalent age of loading and the equivalent duration of loading are introduced to include the effects of the variable temperature and relative humidity on creep. The experiment has been conducted to prove the proposed creep model and the effects of the hydration heat and the change of the service condition on creep have been discussed. It has been found that the hydration heat causes the decrease of the creep and the variations in temperature and relative humidity have obvious influence on the creep characteristic of concrete.