超500 MPa级高强钢抛丸及抛丸后生赤锈表面抗滑移系数试验研究

Experimental investigation of slip factors of grit-blasted surface and rusted surface after blasting for high strength steel over 500 MPa grade

为研究高强钢构件摩擦型螺栓连接抛丸和抛丸后生赤锈两种表面的抗滑移性能,以Q550、Q690、Q890三种等级国产高强钢制作30个试件并进行抗滑移系数测量试验。为了与普通强度钢材进行对比,还增加了Q345钢抛丸表面试件组作为对照。试验结果表明：对于抛丸表面,Q550钢抗滑移系数与规范GB 50017—2003《钢结构设计规范》Q345钢系数取值一致,可取0.50;而Q690和Q890钢的抗滑移系数相对减小,可取0.45。对于抛丸后生赤锈表面,建议设计中不宜考虑生赤锈导致的抗滑移系数增长。另外,为了分析摩擦面抗滑移性能的影响因素,试验测定了各等级钢材的硬度、在相同抛丸条件下的表面粗糙度以及塑性变形能力。分析结果表明,钢材等级越高,表面硬度越高,相同条件抛丸后表面粗糙度越小;抗滑移系数并非表面粗糙度的单一函数,钢材塑性变形能力也显著影响抗滑移系数。

In order to evaluate the performance of the slip critical bolted connection of high strength steel （ HSS ） members, 30 specimens were fabricated from HSS （ Q550, Q690 and Q890 ） to test the slip factors of shot-blasted surface and rusted surface after blasting. For comparison, a group of specimens fabricated from normal strength steel Q345 were tested. According to the test results of the specimens with blasted surface, the suggested slip factor of Q550 steel is the same as the specified slip factor of Q345 steel in GB 50017--2003 ＇ Code for design of steel structures＇ , which is 0.50. For Q690 and Q890 steel, the slip factors tend to be lower and the recommended value is 0.45. The specimens with rusted surface after blasting show an increment in the slip factor owing to the increased surface roughness by rusting. However, because of the relatively large scattering of test results, the increase of the slip factor due to rusting is not recommended to be considered in design. In addition, to investigate the effect of steel grade on slip factor, hardness, roughness and capacity of plastic deformation were measured and analyzed. It is found that, under the same blasting condition, the surface roughness tends to decrease with the increase of steel strength and steel hardness. Moreover, the slip factor is not only decided by surface roughness, but also affected by the capacity of plastic deformation of the contacting materials.