使用超强材料的高恢复混凝土柱的抗震试验研究

最近发生的强震表明，传统的延性结构在超过设计水准强震作用下会产生过大的残余变形而导致结构难以修复. 为保证结构在大变形阶段具有正刚性和较小残余变形，采用低黏结高强度的钢绞线用来代替混凝土柱中的纵向普通钢筋. 为了验证方法的有效性，以钢绞线的布置数量和混凝土的约束方式作为试验变量，对5根缩尺比例为1/3、横截面为250 mm × 250 mm、净高为1 000 mm、剪跨比为2.0和轴压比为0.25的高强混凝土方柱进行拟静力试验. 试验结果表明:低黏高强的钢绞线作为柱纵筋可使混凝土柱的水平承载力在层间位移角达3.5%之前持续保持上升趋势，同时可以有效减少柱的残余变形，并使残余层间位移角控制在相应峰值层间位移角的1/5以下；碳纤维布外包混凝土柱可防止保护层混凝土剥落，进一步减小柱在经历大变形后的残余变形. 

Experimental Study on Seismic Performance of RC Columns Made of Ultra-High-Strength Materials

As recent strong earthquakes have revealed, the excessive deformation of the traditional ductile structures under mega-earthquakes far more than design intensity makes the structures hard to be repaired after earthquakes. To assure sufficient resilience of concrete columns, i.e., stable response and small residual deformation under mega-earthquakes, low-bond and ultra-high-strength (UHS) prestressed concrete (PC) strands rather than deformed reinforcing barsare adopted as the longitudinal reinforcing bars. To verify this method, pseudo-static tests were conducted for five 1/3-scale concrete columns with asquare section of 250 mm × 250 mm, height of 1 000 mm, shear span ratio of 2.0, and axial load ratio of 0.25. The steel amount of UHS PC strand and confinement configuration of transverse reinforcement were experimental variables. Test results indicate that when low-bond and UHS PC strands was used aslongitudinal reinforcement, the lateral resistance of concrete columnskept increasing trend before the drift level reached 3.5%, which effectively reduced residual deformation and limited residual drift below one-fifth of the corresponding peak drift. It is also indicated that carbon fiber reinforced polymer wrapping prevents stripping of concrete cover and further reduces the residual deformation after large deformation of concrete columns.