高强钢与普通钢混合连接抛丸表面抗滑移系数试验研究

Experimental investigation of slip factors for shot-blasted surface of hybrid connections between high strength steel and mild steel

高强度结构钢延性较普通钢差,不宜应用于抗震设计中会出现塑性铰的高延性需求构件。在抗震设防区建筑结构中,高强钢构件宜与普通钢混合使用以满足结构抗震要求。因此,需对高强钢与普通钢混合连接的摩擦面抗滑移性能进行研究。文中以国产Q550、Q690、Q890三种等级高强钢搭配Q235与Q345普通钢制作了30个试件进行混合连接抛丸表面的抗滑移系数测量试验,并将试验结果与同等级高强钢连接抛丸表面抗滑移系数试验结果进行对比。结果表明,混合连接抛丸表面抗滑移系数大于同等级高强钢连接表面抗滑移系数。设计中,建议其取值与同等级高强钢连接表面抗滑移系数保持一致:Q550钢的混合连接抗滑移系数取0.50,Q690与Q890钢混合连接系数可取0.45。为分析抗滑移系数的影响因素,文中测量了同批次试件的钢材硬度、粗糙度、变形能力。分析结果表明,抗滑移系数受到接触表面的粗糙度及摩擦面相对变形能力的影响,而摩擦面相对变形能力受到材料本身塑性及不同材料塑性变形能力匹配度的共同影响;随着钢材等级的增加,抛丸表面粗糙度及钢材变形能力的下降,导致更高等级高强钢混合连接抗滑移系数的降低。

The ductility of high strength steel(HSS) is not as good as mild steel, so that it does not meet the ductility requirement of seismic design. Consequently, the hybrid connection between mild steel and HSS shall be used in the structural design to meet the seismic requirements. In order to evaluate the slip performance of hybrid connections between high strength steel and mild steel, 30 specimens were fabricated from HSS(Q550, Q690 and Q890) and mild steel(Q235 and Q345) to test the slip factors of shot-blasted surface. The test results of slip factors from the 30 specimens were compared with the measured ones from connections with the same steel grade of HSS. According to the test results, the slip factors of hybrid connections are higher than those of connections fabricated by the same grade of HSS plates. In design, it is recommended to take the value of slip factor for hybrid connection the same as that of the connection fabricated by the same grade of HSS plates. The slip factor of 0.50 is recommended for hybrid connections between Q550 and mild steel, while for hybrid connections between Q690(Q890) and mild steel, the slip factor of 0.45 is recommended. Moreover, the hardness, roughness and deformation capability for the same batch of steels were measured to evaluate the effect of steel grade on the slip factor. It is indicated that the slip factor shall be affected by not only surface roughness but also plastic deformation capacity. The deformation capacity depends on both steel plasticity and the difference between steel grades of hybrid connection. With the increase of steel grade, the slip factor of hybrid connection tends to decrease due to the reduction of surface roughness and steel plasticity.