郑州黄河公铁两用大桥杆件受力特点分析

ANALYSIS OF MECHANICAL CHARACTERISTICS OF TRUSS MEMBERS IN ZHENGZHOU YELLOW RIVER HIGHWAY-RAILWAY BRIDGE

经过对郑黄桥的全桥进行受力分析认为郑黄桥为矮塔斜拉桥。通过靠近荷载一侧边桁、中桁,远离荷载一侧边桁的斜腹杆、上弦杆和下弦杆的影响线分析,以及与结构相类似的天兴洲桥研究比较得出:1)从3片桁的受力分配上看,中桁杆件的内力明显比边桁杆件的内力大,而靠近荷载一侧的边桁杆件的内力又远大于远离荷载一侧的边桁杆件内力。2)从杆件的受力来看,中桁和边桁的斜腹杆、上弦杆、下弦杆的内力均以轴力为主,其余内力都较小。3)从各杆件的内力影响线来看,它们的荷载影响跨度只局限在相邻的3个跨度内。其中轴力的荷载影响跨度要明显大于剪力和弯矩的荷载影响跨度。4)从与类似结构形式的直桁架桥比较,斜桁架布置对轴向力、剪力、弯矩影响线的形状改变很小,但是它改变了3片桁内力的分配,加大了中桁的受力,减小了边桁的受力。

After the mechanical analysis of full-bridge,the Zhengzhou Yellow River Highway-Railway Bridge can be defined as an extradosed cable-stayed bridge.Through the influence lines analysis of diagonal brace,upper and bottom cord members in the load-closed side truss,middle truss and load-away side truss,and the comparison of mechanical characteristics of Tianxingzhou Bridge with similar structure,some conclusions can be drawn.1）From the stress distribution in three pieces of trusses,it is obvious that the stress in middle truss is greater than the side truss,and the stress in load-closed side truss is much larger than the load-away side truss.2）From the internal force of truss member,it can be observed that the diagonal brace and cord members are mainly in axial force while other internal forces are small.3）From the observation on the influence lines of truss members,the load impact span is limited in the adjacent three spans,and the load impact span of axial force is longer than the load impact span of moment and shear force.4）Comparing with the other similar structure,the diagonal truss girder has little contributions to the influence line shape of axial force,shear force and moment,but it changed the stress distribution in three pieces of trusses,increased the stress in middle truss,and reduced the stress in side truss.