大跨度混凝土曲线箱梁横截面正应力分布研究

Study of Normal Stress Distribution in Cross Section of Long-Span Curved Concrete Box Girder

为研究主要荷载对大跨度混凝土曲线箱梁横截面正应力的影响程度,以(58+100+58)m三跨变截面预应力混凝土连续刚构箱梁弯桥——坞家湾大桥为工程背景,利用MIDAS/FEA3.6建立全桥精细化实体模型,分析该桥在自重、预应力、车辆荷载、混凝土收缩徐变和温度作用下,曲线箱梁横截面顶底板法向正应力的横向分布规律。结果表明,对称布置的预应力束对曲线箱梁桥内、外两侧正应力大小影响不等;桥梁宽度较小时,受车辆偏载情况影响不明显;正应力大小在混凝土收缩徐变作用下受挂篮施工周期影响明显;温度对三跨连续刚构桥中跨影响不明显,对边跨底板影响较大。

To study the influential degree of main loads on the normal stress distribution in the cross section of long-span curved concrete box girder, the Wujiawan Bridge, a three-span pres-tressed concrete continuous rigid-frame box girder bridge with span arrangement of （58 ＋ 100 ＋ 58） m and with variable cross section, was taken as the study background. The MIDAS/FEA 3. 6 was used to establish the refined solid model of the bridge, to study the transverse distribution traits of the normal stress in the top and bottom slabs of the curved box girder bridge under the action of self-weight, prestress, vehicle load and concrete shrinkage and creep. The results demonstrate that the symmetrically arranged prestressing tendons have minimal influence on the normal stresses in the inner and outer sides of the curved box girder bridge. The effect of vehicle eccentric loads is not obvious when the deck is not very wide. The variation of normal stress is sensitive to the con-struction cycle of the form traveler under the action of concrete shrinkage and creep. Temperature has no obvious influence on the central span of the three-span continuous rigid-frame bridge, but great influence on the bottom slabs of the side spans.