斜度对多梁式连续斜交小箱梁桥力学性能的影响

基于斜交箱梁桥弯扭耦合的受力特点,利用梁格法求解了自重作用下0°,10°,20°,30°,45°,60°共6种情况下多梁式连续小箱梁的弯矩、扭矩、应力和位移,对比分析了斜度对斜交连续小箱梁桥力学性能的影响。研究结果表明,在常用斜度范围(θ60°)内,主梁跨中截面的弯矩、位移随斜度的增大先减小后增大,而墩顶截面的弯矩、跨中截面的扭矩随斜度的增大先增大再减小;各截面上缘应力随斜度的增大先增大后减小,而下缘应力则随斜度的增大先减小后增大;当斜度达到临界斜度45°时,各截面的内力、位移均达到最值,此时,跨中截面扭矩值与正桥跨中截面的扭矩值相差倍数达到了100以上;斜度为0°~10°时,主梁弯矩、应力和位移变化均较小,可近似按直桥计算。在设计中,应充分考虑斜度对斜交箱梁弯扭耦合性能的影响,合理布置墩顶截面和跨中截面的抗弯、抗扭预应力钢束,使设计更经济、安全。

Mechanical behavior of skew contionuous small box multi-girder bridges by skew angle

Based on the mechanical characteristics of bending and torsion coupling,the ben-ding moment,torque,stress and displacement with different skew angles under its own weight were calculated with grillage method and were contrasted with those of right bridge to analyse the mechanical behavior of skew contionuous small box multi-girder bridges af-fected by skew angle.The results show that within the normal range of skew angles,as the skew angle increases,the bending moment and the displacement of the midspan section first decrease and then increase,the bending moment of the pier top section and the torsion of the midspan section first increase and then decrease,the stress at the top first increases and then decreases,the stress at the bottom first decreases and then increases.When the skew angle arrives the critical skew angle 45°,the inner force and displacement of the cross-section are to achieve the most value.In this case,the midspan section torque value is 100 times more than that of the right bridge.When the skew angle is 0°~ 10°,the changes of ben-ding moment,stress,displacement are small,the skew bridge can be approximated by right bridge.It is suggested to reasonably arrange pre-stressing tendons of the pier top sec-tion and the midspan section while designing.