【摘要】 本文针对一种半预制U形钢-混组合盖梁（USCCB），制备了2个缩尺比为1∶2的试件并开展四点弯曲试验，通过涂抹脱模剂模拟钢-混界面脱空以探究其对该类型盖梁力学性能的影响。基于典型截面建立了考虑材料非线性关系的正弯承载能力计算公式。试验结果表明：与脱空试件相比，USCCB的钢外壳与核心混凝土协同变形能力强，钢-混界面未出现明显脱空现象。极限荷载下2个试件均表现为跨中混凝土先压溃，随后翼缘板发生不同程度的屈曲变形。脱空试件极限承载力降低约5.9%，跨中挠度、延性系数和塑性系数分别增加24.8%、31.6%和3.2%，在此基础上通过弯曲破坏计算公式对等效矩形应力图高度系数进行了修正，建议取0.7～0.8。更多还原

【Abstract】 In this study, two 1∶2 scale specimens of a semi-precast U-shaped steel-concrete composite cap beam(USCCB) were fabricated and tested under four-point bending. Interfacial debonding between the steel and the encased concrete was simulated by applying a release agent to investigate its impact on the mechanical performance of this type of cap beam. Based on the typical cross-section, a calculation formula for the positive moment bearing capacity was established with consideration of material nonlinearity. The experimental results show that compared with the debonded specimen, the USCCB exhibits strong synergetic deformation between the steel shell and the encased concrete, with no significant interfacial debonding observed. Under ultimate load, both specimens failed due to the initial crushing of the mid-span concrete, followed by varying degrees of buckling in the flange plates. For the debonded specimen, the ultimate bearing capacity decreased by approximately 5.9%, while the mid-span deflection, ductility coefficient, and plasticity coefficient increased by 24.8%, 31.6%, and 3.2%, respectively. Furthermore, the equivalent rectangular stress block height coefficient was refined through the positive moment capacity calculation formula.It is suggested that the correction factor be taken as 0.7 ～ 0.8.更多还原