Seismic Behavior of Specially Shaped Column Joints with X-Shaped Reinforcement

To investigate the seismic behavior of specially shaped column joints with X-shaped reinforcement,two groups of specimens with or without X-shaped reinforcement in joint core region were tested under constant axial compression load and low reversed cyclic loading,which imitated low to moderate earthquake force.The seismic behavior of specially shaped column joints with X-shaped reinforcement in terms of bearing capacity,displacement,ductility,hysteretic curve,stiffness degradation and energy dissipation was studied and compared to that without Xshaped reinforcement in joint core region.With the damage estimation model,the accumulated damage was analyzed.The shearing capacity formula of specially shaped column joints reinforced by X-shaped reinforcement was proposed with a simple form.The test results show that X-shaped reinforcement is an effective measure for improving the seismic behavior of specially shaped column joints including deformation behavior,ductility and hysteretic characteristic.All specimens were damaged with gradual stiffness degeneration.In addition,X-shaped reinforcement in the joint core region is an effective way to lighten the degree of cumulated damage.The good seismic performance obtained from the specially shaped column joint with X-shaped reinforcement can be used in engineering applications.The test value is higher than the calculated value,which indicates that the formula is safe for the design of specially shaped column joints.

Influence of Girder Vibration on Cable Damper's Performance of A Cable-stayed Bridge

The model combined by cable,girder and damper is founded to study the influence of girder vibration on cable damper 's performance of a cable-stayed bridge. The complex mode method and nondimensionalization are used to analyze the relationship between the girder's parameters and the performance of cable-related damper. The results indicate that the performance of cable-related damper will decrease greatly when the girder frequencies are near the frequencies of cable. The smaller absolute displacement of damper's piston caused by the very small vibration phase shift of girder and cable is the physical cause of the negative impact mentioned above.

Construction scheme comparison with comprehensive evaluation of independent perspectives

Considering both the characteristics of construction scheme evaluation and the lack of consideration of index proportionality after introducing comprehensive evaluation of independent perspectives into construction scheme evaluation, a construction scheme evaluation model of independent perspectives was put forward through the study and optimization of comprehensive evaluation of independent perspectives. The feasibility and rationality of the optimized method were illustrated through a case study and the evaluation results were compared between the optimized method and non-optimized method. The optimized method has the practical value in construction scheme comparison.

Predicting unstable toughness of concrete based on initial toughness criterion

研究目的:研究混凝土失稳韧度的理论预测方法。创新要点:1.提出混凝土失稳韧度的理论预测方法;2.利用楔入劈拉试件计算不同级配混凝土的失稳韧度;3.研究失稳韧度受拉伸软化曲线的影响。研究方法:1.基于起裂韧度扩展准则,采用理论分析手段研究混凝土的失稳韧度计算方法;2.利用楔入劈拉试件(见图3)计算不同级配混凝土的失稳韧度。重要结论:1.基于起裂韧度准则可合理地预测峰值荷载状态及失稳韧度;2.混凝土失稳韧度受断裂能的影响较小;3.拉伸软化曲线对混凝土失稳韧度的影响较小。