部分外包混凝土组合梁负弯矩区翼缘板裂缝试验研究

Experimental Study on Slab Cracks in the Negative Moment Regions of Partially Concrete Encased Composite Beams

为了研究部分外包混凝土组合梁在负弯矩作用下混凝土翼缘板裂缝分布及发展情况,对6根部分外包混凝土组合梁和两根普通钢-混凝土组合梁进行了静力加载试验研究。通过对比试验发现:与普通钢-混凝土组合梁相比,部分外包混凝土组合梁负弯矩区截面刚度较大,混凝土翼缘板的裂缝开展比较缓慢,且具有较大的开裂弯矩值;随着组合梁负弯矩区综合力比的增加,混凝土翼缘板的平均裂缝间距与最大裂缝宽度均有减小的趋势。在试验研究的基础上,提出了部分外包混凝土组合梁负弯矩区混凝土板开裂弯矩和裂缝宽度计算公式,对开裂截面混凝土翼缘板的塑性发展与钢筋应变不均匀现象进行了探讨,为部分外包混凝土组合梁在实际工程中的应用提供参考和理论依据。

In order to investigate the distribution and development of slab cracks in the negative moment regions of partially concrete encased composite beam（PECB）,six PECBs and two common steel-concrete composite beams are tested under static loading.Experimental results show that compared with common composite beams,PECBs have higher stiffness with reinforced concrete encased in the web of the joist,which contributes to bigger crack moment and slower crack development.Crack distance and maximum crack width of concrete slab decrease gradually with increasing combined force ratio in negative bending region.Formulas for calculating crack moment and crack width of concrete slab are established.Besides,the uneven distribution of reinforcement strain and plastic development of concrete slab are discussed.The analysis results can provide references to the application of PECBs in real projects.