一种梁受弯加固的钢丝绳预应力张拉控制试验研究

Experimental Study on Tension Control of Prestressed Steel Wire Rope for Flexural Strengthened Beam

针对钢丝绳-聚合物砂浆面层加固中钢丝绳预应力张拉需要,提出了一种采用扭矩扳手施加预应力的实用方法.通过在张拉螺杆上施加不同拧紧扭矩,研究了钢丝绳张拉力变化规律和预应力损失机理,得到扭矩系数、有效预应力系数和预应力损失率.结果表明:张拉螺杆的拧紧扭矩与钢丝绳张拉力呈线性关系,扭矩系数k约为0.2192.预应力损失主要集中在张拉锚固结束后的5min内,其损失量约占总损失量的50%;7h之后,钢丝绳张拉力保持不变,有效预应力趋于稳定.基于试验结果,得到不同拧紧扭矩下的钢丝绳张拉力、有效预应力系数和预应力损失率计算公式,计算结果与实验结果吻合良好.

A practical method of applying torque wrench to prestress the steel wire rope in the flexural strengthening with steel wire rope-polymer mortar composite is proposed.The rule of tension change and the prestress loss mechanism of steel wire rope are studied.The torque coefficient, effective prestress coefficient and prestress loss rate are experimentally obtained.The test results show that the tension torque has a linear relationship with the tension force on the wire rope, and the torque coefficient k was about 0.2192.The prestress loss mainly occurred a short period, about 5 min, after the wire rope was tensioned and anchored, and the value accounted for about 50% of the total prestress loss for 72h.After 7h anchoring, the tension of the wire rope basically remains unchanged, and the effective prestress tends to be stable.Based on the test results, the formulas for calculating the tension, effective prestress coefficient and prestress loss rate of the wire rope under different tensioning moments are put forward.The accuracy of the formula is verified by calculation results and experiments.