自锚式梁下斜张简支桥梁的冲击系数研究

Research on Impact Coefficient of Self-anchored Under-deck Cable-stayed Simply Supported Bridges

以梁下斜张简支梁为研究对象,根据规范计算得到其冲击系数,并与无斜张索的简支梁冲击系数进行对比。基于瞬态响应分析法,通过ANSYS有限元计算,得到在不同速度移动荷载作用下,不同主梁截面形式、不同撑杆布置形式的梁下斜张简支梁桥主梁各点的冲击系数分布规律,并对不同大小的移动荷载作用下的主梁跨中冲击系数进行参数分析。结果表明:①梁下斜张简支梁桥的冲击系数大于相同主梁的简支梁桥;②斜张梁的冲击系数分布规律均为梁端处较大而跨中处较小;③主梁截面形式、撑杆布置形式及移动荷载速度均对冲击系数造成较明显影响,而移动荷载大小对跨中冲击系数的影响不明显。

Impact coefficient of under-deck cable-stayed bridge calculated by the current code was contracted with that of simply supported beam without stay cables. The distribution law of impact coefficient of under-deck cable-stayed simply supported bridges, with different deck sections and different strut arrangements, under moving loads with various speeds, was found out by calculation of ANSYS software according to transient response method. The parameter analysis of impact coefficient at midspan under various moving loads was also done. As the results shown,(1) the impact coefficient of under -deck cable-stayed bridge is larger than that of simply supported beam without stay cables,(2) the impact coefficient at the end of deck is larger than that at midspan,(3) the impact coefficient is greatly influenced by deck section, struts arrangement and moving load speed, and moving load has no obvious effect on the impact coefficient at midspan.