L型及J型地脚螺栓抗拔试验及理论分析

Experimental Study and Its Calculation Theory of L-type and J-type Anchor Bolts

基于对国内外地脚螺栓抗拔承载力的归纳分析,针对不同锚固长度、锚固型式,本文分别开展了光圆型地脚螺栓、90°L型和180°J型地脚螺栓的抗拔承载力试验,并将试验结果与相关文献规范进行对比分析。试验表明,地脚螺栓在上拔荷载作用下,基于不同的锚固长度,有三种典型的破坏形式:(1)地脚螺栓达到抗拉承载力极限;(2)基础混凝土与地脚螺栓杆的粘结破坏;(3)圆锥形混凝土达到抗拉承载力极限。锚固长度为5d时,地脚螺栓抗拔承载力试验值约为理论值的40%～60%,锚固长度为10d,15d时,试验值约为理论值的20%～30%;且采取机械锚固措施的地脚螺栓可以极大地提高其抗拔承载力。地脚螺栓应变在混凝土内部分布是不均匀的,在混凝土表面处锚栓应变最大,随着锚固长度增加,应变逐渐减小。

Based on the analysis of uplift bearing capacity of domestic and foreign anchor bolt induction,pullout tests are carried out with single round anchor bolt 90 degrees L and 180 degrees J type anchor bolts in different single anchorage depth,and results are comparatively analyzed with related literature specification.The test shows that there are three typical failure modes of anchor bolt under uplift load,based on different anchorage length:(1)anchor bolt achieve the ultimate uplift capacity;(2)bonded concrete foundation and foundation bolt rod failure;(3)conical concrete reaches the tensile bearing capacity limit.When the anchorage length is 5 d,the experimental value of the uplift bearing capacity of the anchor bolt is about 40%~60%of the theoretical value.When the anchorage length is 10 d and 15 d,the experimental value is about 20%~30%of the theoretical value.And the anchor bolt with mechanical anchorage measures can greatly improve the uplift bearing capacity.The strain distribution of the anchor bolt is not uniform in the concrete.The strain of anchor bolt is the largest on the surface of concrete,and the strain decreases with the increase of anchorage length.