The present study investigated the effects of shear slip on the deformation of steel-concrete composite beams. The equivalent rigidity of composite beams considering three different loading types was first derived based on equilibrium and curvature compatibility, from which a general formula to account for slip effects was then developed. The predicted results were compared with measurements of six specimens tested in the present study and other available test results for both simply supported and continuous beams. It was found that including slip effects has significantly improved the accuracy of prediction. For typical beams used in practice, shear slip in partial composite beams has a significant contribution to beam deformation. Even for full composite beams, slip effects may result in stiffness reduction up to 17% for short span beams. However, slip effects are ignored in many design specifications that use transformed section method except that American Institute of Steel Construction (AISC) specifications recommend a calculation procedure in the commentary. In the AISC procedure, stress and deflection calculations of partially composite girders are based on effective section modulus and moment of inertia to account for slip, while ignoring slip effects in full composite sections. For full composite sections, the effective section modulus and moment of inertia calculated with the AISC specifications are larger than that of present study, meaning that the specifications are not on the conservative side. For partial composite sections, the AISC predictions are more conservative than the present study.

Static loading tests were conducted on 16 steel-concrete composite beams and two steel beams to investigate shear resisting mechanisms and the strength of composite beams. The main experimental parameters were the shear span aspect ratio of the simply supported beams, and the width and thickness of the concrete flanges. Based on strain measurements, stress in the steel beam was analyzed using theories of elasticity and plasticity, and the vertical shear that the steel beam resisted was calculated. The shear resistance of the concrete flange was then obtained by subtracting the steel shear contribution from the total load applied. It was found that the concrete flange could sustain 33-56% of the total ultimate shear applied to the composite beam specimens, contrary to the typical assumption of neglecting the concrete shear contribution in most design codes and specifications. A shear strength equation that considers the shear contributions of both the steel beam and the concrete flange is proposed.

有端横梁约束的简支单向组合梁-板体系在横向荷载作用下，由于剪力连接件的约束，翼缘板中存在剪力滞后现象。结构体系中，端横梁对剪力滞后程度有很大影响。本文采用有限元方法，对翼缘有效宽度的主要影响因素进行参数分析，其中包括宽跨比、荷载类型、滑移刚度、端横梁约束程度等，并拟合出了各种情况下有效宽度的简化计算公式，通过与有限元方法及其它计算方法的对比，说明了本文公式的准确性。

This paper describes an experimental study on behavior of steel and high-strengrth concrete (HSC) composite beams. Seven model HSC composite beams and one normal. strength concrete (NSC) beam were tested under monotonic loading. All beams were designed for a full shear connection between the steel beam and the concrete flange USing shear studs. It was identified that the HSC composite beams had higher initial stiffness and very distinct post. yielding characteristics compared wim the NSC beam. Test results of the HSC specimens also showed several favorabte design aspects such as a larger margin beyond the steel yielding and greater ultimate deformability. Analysis based on the current design codes can providea reasonable estimation to the flerural bzitial stiffness andul timate flexural capaci of the HSC composite beams.

对钢-混凝土组合梁的长期变形问题进行了分析和讨论。指出我国现行（钢结构设计规范）关于组台梁长期变形的计算值偏小。并建立了组合梁的长期剐度计算公式。反映了混凝土徐变系数大小的影响。同时还考虑了混凝土收缩对变形的影响。公式意义明确。形式简单，应用方便。