连续钢桁结合梁桥负弯矩区桥面系受力影响因素和改善方法研究

以1座下承式连续钢桁结合梁桥为例,采用有限元法研究了桥面系的受力特性,考察了中支座区域桥面系受力状态与混凝土板板厚、纵梁抗拉刚度及抗弯刚度的关系;针对纵横梁及混凝土板在中支座区域受力比其他区域突出的问题,探讨解决方案。研究结果表明:在中支座两侧节间内,随着纵梁抗拉刚度的增加,纵梁轴力增加速度逐渐减慢,且低于抗拉刚度的增加速度;随着纵梁抗弯刚度的增加,纵梁竖向弯矩也增加;采用较高的纵梁或增加混凝土板厚对降低中支座区域纵横梁的应力效果并不明显,相对而言,选择合适的纵梁高度并增加翼缘厚度或采用4根小纵梁的方法均可降低该区域纵横梁的应力水平,在中支座两侧节间内再布置横梁时纵横梁的应力可进一步降低。

The effect factor and improving method of the mechanical state of the floor system in a negative moment area of a continuous truss composite bridge

Based on a continuous through truss composite bridge,several problems including mechanical behavior of the floor system,the influence of the deck's thickness and the longitudinal beam's tension/bending stiffness on the load applied at the middle support region,were studied with the finite element method.Improving methods were introduced to reduce stresses of the floor system at the region.The results show that in the two panels near the middle support,the increasing speed of the longitudinal beam's axial force turns slow and is less than that of tension stiffness with the growth of tension stiffness;The longitudinal beam's bending moment gets large with the increase of bending stiffness;The transversal beam at middle support bears more load with the increase of the longitudinal beam's tension/bending stiffness and the deck's thickness.So it is ineffectual to reduce stresses of the longitudinal/transversal beam in the middle support region by increasing the deck's thickness or the longitudinal beam's height.On the contrary,the methods,such as choosing appropriate height of the longitudinal beam or adopting four longitudinal beams can reduce stresses of the longitudinal/transversal beam in the region.And adding transversal beam within the two panels near the middle support region,the stresses can reduce further.