预制节段钢纤维混凝土梁干接缝抗剪性能试验

预制节段混凝土梁的干接缝具有不连续性，是薄弱环节和重要部位，在设计和施工期间需要得到更多的重视。以接缝类型（整体式接缝和单键齿干接缝）、混凝土类型（C60混凝土和CF60钢纤维混凝土）、钢纤维掺量（40，60，80 kg·m^-3）和水平正应力（0.5，1.0，2.0 MPa）作为试验参数，对18个C60混凝土和CF60钢纤维混凝土试件进行直剪性能试验，记录试件开裂载荷、极限载荷和残余载荷，观察试件裂缝形态和破坏模式，研究规范化剪应力-垂直位移曲线以及载荷-水平位移关系，并将极限抗剪强度试验值与AASHTO 2003规范和其他设计公式计算值进行比较。应用有限元分析软件ABAQUS对试验进行数值模拟。研究结果表明：极限剪切荷载模拟值与实测值吻合良好，模拟的键齿裂纹开展情况与试验吻合；使用钢纤维混凝土可提高整体试件和单键齿接缝的抗裂性、抗剪强度、残余载荷和规范化极限剪应力；钢纤维可以改善整体式和单键齿试件的变形能力，并且随着钢纤维掺量的增加，单键齿试件的开裂荷载、极限荷载和残余荷载也随之增大；AASHTO 2003规范和其他设计公式都低估了C60混凝土和CF60钢纤维混凝土单键齿干接缝试件的抗剪能力，公式偏安全，其中Alcalde公式预测值更吻合，Rombach公式预测最保守。

Test on Shear Behavior of Dry Joints in Precast Steel Fiber Reinforced Concrete Segmental Bridges

Dry joint between segments represents the weak location and discontinuity but important of precast concrete segmental bridges (PCSBs), which need to be paid more attention in design and construction period. In this study, the shear behavior of 18 specimens of dry joints cast using the C60 or CF60 steel fiber reinforced (SFR) concrete was investigated. The experimental parameters considered for the investigation were joint type (monolithic joints or single-key dry joints), concrete type (conventional or SFR), aspect ratio of steel fiber (40 kg·m^-3, 60 kg·m^-3, and 80 kg·m^-3), and horizontal confining stress level (0.5 MPa, 1.0 MPa, and 2.0 MPa). Cracking loads, ultimate loads, and residual loads were recorded, and the cracking patterns and failure modes were observed. The normalized shear stress-vertical slip curve and load-horizontal dilation relationship were investigated. Meanwhile, finite element method models were created using ABAQUS to simulate the test. The finite element analysis results and the experimental results demonstrate good agreement in terms of the ultimate shear load and the crack formation sequence. From the results, it can be concluded that the use of SFR concrete can improve cracking load, shear strength, residual load, and normalized ultimate shear stress of both monolithic specimens and single-keyed dry joint specimens. In addition, the deformation capacity of both monolithic specimens and single-keyed dry joint specimens is improved by the use of steel fibers. The cracking load, ultimate load and residual load of all single-keyed dry joint specimens increase with the increasing ratio of steel fiber. The results obtained in these tests, as well as those found in the literature, were compared with the AASHTO 2003 provisions and other design formulae for assessing the load carrying capacity of the dry joints. It is found that the AASHTO 2003 provisions and several other design formulae underestimate the shear capacity of single-keyed dry joint specimens of both C60 and CF60 SFR concrete. The result obtained using Alealde's formula is more consistent with the experimental results than that of the other formulae, while the results obtained using Rombach's formula are the most conservative.