中文摘要：

以某钢筋混凝土箱梁为原型，按截面主要尺寸基本相似的原则，制作了1：10与1：5两种比例4片钢筋混凝土试验梁。试验主要研究了箱形截面梁与等效工字形截面梁抗剪性能的差异，并比较不同比例下试验梁的尺寸效应。试验及分析结果表明：箱梁抗剪承载力比相同配筋率等效工字形截面梁约低8．5％，薄壁箱梁的抗剪承载力利用等效工字形梁的公式进行计算是偏于不安全的；试件尺寸增加一倍，箱梁抗剪承载力试验值与理论值之比降低3．9％，工字梁降低3．O％，实际结构中，箱梁截面尺寸更大，现有规范公式的适用性值得进一步研究。

英文摘要：

Four reinforced concrete girders, two with box sections and the other two with equivalent I sections, manufactured at the scale of 1：10 and 1：5, respectively, to study the different shear resistance behaviors between the box girder and the equivalent I-shape girder, and compare the size effect between them. The result shows that the shear resistance of the box girder is about 8.5% lower than those of the equivalent I-shape girder, therefore, it is not completely safe to measure the shear resistance of the box girder with the formula for the equivalent I-shape beam. When the size is doubled, the shear resistance ratio of the experimental value to theoretical value is reduced by 3.9% for the box girders and 3.0% for the I-shape girders. According to the comparison, and taking account that the size of box girders in actual structures is much larger, the adequate safety margins of employing existing method for shear resistance