型钢混凝土十形柱空间节点受剪机理及抗剪强度研究

Shear mechanism and shear strength of steel reinforced concrete(SRC)cross-shape 3D column-beam joints

为了研究型钢混凝土(SRC)十形柱空间节点在斜向荷载作用下的受剪机理、抗裂承载力及抗剪承载力,开发一套加载装置,采用柱端斜向加载方式对5个型钢混凝土十形柱空间节点进行低周反复荷载试验。观察节点核心区剪切面破坏形态,分析节点区两个主轴方向的箍筋、水平腹杆、钢腹板的应变分布规律及空间节点受剪机理和抗剪影响因素。结果表明:节点受剪面破坏为典型的剪切斜压黏结破坏;两主轴方向的箍筋、水平腹杆及钢腹板应变分布规律基本相同;空间节点受剪机理与型钢混凝土异形柱框架平面节点有着共性,但斜向荷载作用下,空间节点抗剪能力变弱,受力更为复杂。斜向加载角度对抗裂承载力影响不明显,而对抗剪承载力的影响应予以考虑,抗剪承载力与斜向荷载角度相关曲线近似于菱形。最后,基于各种配钢形式的SRC十形柱空间节点单向受剪下(沿工程轴)抗剪承载力计算方法的研究,提出在斜向荷载作用下节点抗裂承载力及抗剪承载力计算公式,计算结果与试验值吻合较好。

To investigate the failure modes,shear mechanism,crack resistance and shear bearing capacity of SRC crossshape 3D column-beam joints,the experimental investigations were conduced based on the studies of the 5 joints under oblique low-cycle repeated loading at the column end,and a set of novel loading device was developed. Strain distributions along two axial directions in the stirrups,web members,and steel web,the shear mechanism and the influencing factors of shear resistance for 3D joints were then analyzed. The test results indicate that the typical failure mode of the joint was shear diagonal compression failure. The strain distributions along two axial directions in the stirrups,web members and steel web were identical. The shear mechanism of SRC cross-shape 3D column-beam joints was similar to that of 2D planar joints. Under the oblique loading,however,the shear resistance of 3D joints may attenuate and the stresses were more complicated. The effect of oblique loading angle on crack resistance was not obvious,but its effect on shear resistance should be considered the relationship between shear bearing resistance and oblique loading angle was approximate diamond-shaped. In the end,based on the shear analysis of different SRC crossshape 3D column-beam joints under unidirectional loading,the formulas for crack resistance and shear resistance of 3D joints under the oblique loading were put forward. By the comparisons,it was found that the calculation results agreed well with the test results.