预应力矮肋T梁桥跨中横隔梁力学性能及计算方法分析

Analysis of Mechanical Properties and Calculation Method of Mid-Span Transverse Beam of Prestressed Low-Ribbed T-Beam Bridge

由于预应力矮肋T梁桥结构高度小,主梁抗扭刚度小,桥梁在受力时,力在桥梁上的横向分布会与普通T梁不同,横隔梁的力学性能也会发生变化。为了解预应力矮肋T梁桥跨中横隔梁的力学性能以及掌握预应力矮肋T梁桥跨中横隔梁的合理计算方法,本文通过全桥有限元分析方法、偏心压力法理论对预应力混凝土矮肋T梁桥跨中横隔梁进行受力性能分析,然后与现场试验结果进行对比分析。结果表明:横隔梁截面应力沿梁高成线性分布;有限元分析方法的计算结果与试验结果的最大误差为9.4%,最小误差为1.5%;运用偏心压力法的计算结果与试验结果的最大误差为27.7%,最小误差为10.5%;采用偏心压力法计算的中性轴位置与实际中性轴位置有偏差。可见横隔梁受力均匀,工作状态良好;全桥有限元分析方法可很好的模拟预应力矮肋T梁桥横隔梁的受力性能,理论计算的横隔梁的应力与试验结果吻合,误差小于9.4%,计算精度高,可用于实际工程设计当中;采用偏心压力法理论对预应力矮肋T梁桥的横隔梁进行内力计算是不太适用的,计算精度不高,不能真实的反应梁的实际受力情况;偏心压力法理论计算不够精确的原因是受压翼缘板的有效翼缘宽度计算不够合理。

Due to the small structural height of the prestressed low-ribbed t-beam bridge and the small torsional stiffness of the main beam,the transverse distribution of the force on the bridge will be different from that of the ordinary t-beam when the bridge is under stress,and the mechanical properties of the transverse beam will also change.In order to understand the mechanical properties of the mid-span transverse beam of the prestressed low-ribbed T beam bridge and master the reasonable calculation method of the mid-span transverse beam of the prestressed low-ribbed T beam bridge,based on the finite element method of the whole bridge and the theory of eccentric pressure,this paper analyzes the mechanical behavior of the mid-span transverse beam of the prestressed concrete low-ribbed t-beam bridge,and then makes a comparative analysis with the field test results.The results show that the cross section stress is linearly distributed along with the beam height.The maximum error of the finite element method is 9.4%and the minimum error is 1.5%.The maximum error of the eccentric pressure method is 27.7%and the minimum error is 10.5%.The neutral axis position calculated by eccentric pressure method deviates from the actual neutral axis position.It is concluded that the transverse beam is in good working condition.The finite element analysis method of the whole bridge can well simulate the mechanical behavior of the transverse beam of prestressed low-ribbed t-beam bridge.It is not suitable to calculate the internal force of the transverse beam of the prestressed t-beam bridge by using the theory of eccentric pressure.The theoretical calculation of eccentric pressure method is not accurate enough,and the reason is that the effective flange width calculation of the compression flange plate is not reasonable enough.