损伤拉索的等效弹性模量及其参数分析

损伤拉索会出现线形松弛、应力水平降低的情况,必然会影响拉索的等效弹性模量。本文首先引入损伤程度、位置及范围3个参数,用以描述拉索损伤形态的特征,建立损伤拉索索力和线形计算公式,采用数值方法计算了损伤拉索弦向等效弹性模量精确数值,并和经典的等效弹性模量公式的计算结果进行了比较分析,分析了考虑损伤时两种不同计算方法结果的误差。计算表明,对于500m弦向长度以内的损伤拉索,拉索的弦向长度Lc越大,倾角越小,等效弹性模量的损失越大,并且应用割线模量公式计算的误差也越大,当Lc=500m时,损伤拉索相对误差值在2.5%~4.5%之间。弦向应变越小,等效弹性模量损失越大,弦向应变在0.001,0.004]内,应用割线模量公式计算的相对误差小于3.5%。损伤程度及损伤范围对引用等效弹性模量公式的误差影响较大,倾角对等效弹模公式相对误差的影响也不容忽视。弦向长度、弦向应变、倾角和损伤程度参数都是通过改变拉索的松弛程度进而影响等效弹性模量的数值以及公式的误差。

The equivalent elastic modulus of damaged cables and parameter analysis

Stress loss and linear relaxtion will happen in damaged cables,which inevitably affect the equivalent elastic modules of cable.The damage degree,damage location and damage range are introduced to describe the damage characteristics.The tension and deflection formulas of cables are deduced to calculate the accurate value of the equivalent elastic modules of the damage cable by numerical method.These results are comparied with those calculated by the classical Dischinger secant modulus of elasticity formula,and furthermore,the error between the two methods is declared.The results show that when L_c=500 m for a damaged cable,the loss amount of the equivalent elastic modules is greater in the condition of the damaged cable with larger chord length and smaller inclination angle,so it does to the error induced by the Dischinger secant modulus of elasticity formula.The relative error is between 2.5%~4.5% when L_c=500 m for a damaged cable.The bigger the chord strain,the more the loss of the modulus of elasticity.When the chordwise strain ranges from 0.001 to 0.004,the error is less than 3.5% calculated by Dischinger secant modulus of elasticity formula.The damage degree has a great impact on the error calculated by the original Dischinger formula,as well as the damage range and the inclination angle of the stay-cables.The effect on the accurate equivalent elastic modules of cable and the corresponding error by chord length,chord strain,damage parameter and inclination is all basically induced by changing the sag of the cable due to damage.