匝道小半径单箱槽形组合连续梁桥设计关键技术

Key Technologies for Design of On-ramp Small-radius Single-box Slot Composite Continuous Beam Bridges on Ramps

摘要:

长沙市某立交匝道桥曲线半径150 m，采用单箱槽形钢混组合连续梁结构，跨径布置为35 m+53 m+35 m。以此为工程背景，对比分析MIDAS单梁与梁格模型，明确了若采用理想化闭口箱形截面单梁模型，能够解决曲线小半径单箱钢混组合梁在组合前因槽形开口截面计算抗扭刚度不足而导致的计算结果失真问题；同时就负弯矩区桥面板抗裂措施、结构抗倾覆能力提高、负弯矩区组合与叠合技术应用等设计要点进行分析，确认了以上设计措施的有效性。

Abstract:

The curve radius of an interchange ramp bridge in Changsha is 150 m, and a single-box slot steel-concrete composite continuous girder structure is adopted. Its span layout is 35 m+53 m+35 m. Based on this engineering background, the MIDAS single beam and beam lattice models are compared and analyzed to clarify that the problem of calculation distortion caused by insufficient calculation of torsional stiffness of single-box steel-concrete composite beams with small curved radius before assembling can be solved if a single beam model with idealized closed box section is adopted. And the design essentials such as crack resistance measures for bridge deck slabs in negative bending moment zone, improvement of structural overturning resistance, and application of negative moment region combination and superposition technology are analyzed to confirm the effectiveness of the above design measures.