为研究波形钢腹板PC组合箱梁抗火性能及抗火设计方法，采用ANSYS软件建立热-力耦合分析模型，分析了受火工况下组合箱梁的挠度、侧向位移、钢束张力以及抗弯承载能力的变化规律，并以组合箱梁的挠度和腹板侧向位移为判定指标，提出了一种关于波形钢腹板组合箱梁的抗火设计方法。结果表明：荷载比是影响组合箱梁挠度发展的关键因素；受火全过程中，钢束张力的变化对组合箱梁挠度、侧向位移以及承载能力的变化影响较大；组合箱梁受火初期挠度增长缓慢，在横隔板处形成塑性铰后，跨中挠度快速增大，然后在加载处形成塑性铰，随即组合箱梁因顶板被压碎而破坏；采用抗力准则判断组合箱梁的耐火极限偏于不安全；通过在组合箱梁的波形钢腹板转角处增设立柱，能够减缓组合箱梁挠度和腹板侧向位移的发展，有效提高该类组合箱梁的抗火性能，当无立柱组合箱梁达到耐火极限时，有立柱组合箱梁跨中挠度为无立柱组合箱梁跨中临界挠度的64.3%。研究成果可为该类型组合箱梁的抗火设计提供参考。
Steel–concrete composite box beams are widely used in bridge engineering, which might bear transverse and longitudinal bending moments simultaneously under vehicle loads. To investigate the fatigue performance of joints between the steel girders and the top reinforced concrete (RC) slabs under transverse bending moments, a reduced scale joint between the weathering steel girder with the corrugated steel web (CSW) and the top RC slab was designed and tested under constant amplitude fatigue loads. Test results show that the joint initially cracked in the weld metal connecting the CSW with the bottom girder flange during the fatigue loading process. The initial crack propagated from the longitudinal fold to the adjacent inclined folds after the specimen was subjected to 7.63 × 105 loading cycles and caused the final fatigue failure. Compared with the calculated fatigue lives in the methods recommended by EC3 and AASHTO, the fatigue performance of the details involved in the joint satisfied the demands of fatigue design. Meanwhile, finite element (FE) models of joints with different parameters were established to determine their effect on the stress ranges at the hot spot regions of the joints. Numerical results show that improving the bending radius or the thickness of the CSW helps to reduce the stress ranges in the hot spot regions, which is beneficial to enhance the fatigue resistance of the investigated fatigue details accordingly.
为了解多主梁钢箱-叠合板组合梁桥的受力特性及其影响参数,以某 60m跨多主梁钢箱-叠合板简支组合梁桥右幅桥为背景,开展成桥试验及有限元分析.对该桥分别进行静载试验、环境振动试验、无障碍行车试验,结合有限元计算结果,分析主梁应变、挠度、模态及冲击系数等,并研究钢箱梁高度、混凝土板厚、横向联系梁高度对结构横向受力的影响.结果表明:多主梁钢箱-叠合板组合梁桥在设计荷载下结构均处于弹性状态,钢箱梁与叠合板可以实现协同工作,整体性能良好;钢箱梁高度越小、横向联系梁高度越大,结构整体性能越好,混凝土板厚对结构横向受力的影响较小.
针对传统短束预应力筋存在的问题,提出一种主要由中空管和穿过中空管的反力钢棒等组成的自平衡预应力中空管构造.为了解采用自平衡预应力中空管的混凝土梁的传力特性,采用有限元与试验相结合的方法分析锚垫板设置情况、混凝土强度、中空管尺寸、有效预应力对中空管预应力传递长度的影响,提出中空管预应力传递长度简化计算公式.结果表明:自平衡预应力中空管可作为有锚垫板的先张预应力钢筋传递预应力;预应力传递长度与中空管尺寸、有效预应力近似成正比,与混凝土抗拉强度近似成反比;现有国内外规范均不适用于中空管预应力传递长度的计算,所提出的简化计算公式计算的中空管预应力传递长度与实测值吻合良好;实桥应用结果显示采用自平衡预应力中空管的混凝土梁预应力传递特性和试验结果相符,预应力传递可靠.
为了解波形钢腹板箱梁高墩连续刚构桥的抗震性能,以某最大墩高 85.14m的波形钢腹板箱梁三跨连续刚构桥为背景进行有限元分析.采用A baqus软件建立该桥有限元模型,基于反应谱法分析其在E1 和E2 地震各向(横桥向、顺桥向、竖向)作用下的桥梁结构受力及变形性能,并与等效预应力混凝土箱梁连续刚构桥模型的计算结果进行对比.结果表明:波形钢腹板箱梁连续刚构桥与等效预应力混凝土箱梁连续刚构桥的主梁沿地震输入方向上的位移大于其它 2个方向的位移,相较于等效预应力混凝土箱梁桥,波形钢腹板箱梁桥的抗震性能更优,但其边跨底板正应力更大,需要重点关注.
