盲孔法识别拉(压)弯钢管内力的分析与试验

Analysis and experimental study on identification of inner force of steel tube under tension(compression) and bending using blind-hole method

为了解在役拉(压)弯钢管的内力情况,在盲孔法测量钢结构应力的基础上,提出了拉(压)弯钢管的内力识别方法.采用盲孔法对不同外径、不同荷载下的3组9根钢管试件进行了2种不同方式下的钻孔试验,研究了不同钻孔方式、不同外径、不同表面应力分布情况下的钻孔释放规律.试验结果表明:钻孔加工应变对测量精度影响较大,计算应力时应消除钻孔加工应变的影响;在应力超过fy/2时需对释放系数进行塑性修正;钢管表面应力的测量精度随钢管直径的增大而提高.盲孔法用于拉(压)弯钢管的表面应力检测和杆件内力识别,无论理论上还是实际操作都是可行的,识别精度满足工程应用要求.

To find out the inner force of existing steel tube under tension（compression） and bending,a method based on stress measurement of steel structure using blind-hole method is proposed to identify the inner force of the member.Experimental investigations with two different hole-drilling manners were carried out on nine steel tubes of different diameter and loading.The rules of the strain release were studied under different diameters,hole-drilling manners,and distributions of surface stress when the holes were drilled.The experimentation indicates that the measurement precision is greatly influenced by the strains induced by drilling hole（as called drilling strain）,the influence of drilling strains should be eliminated when stress is calculated;the strain release factors should be corrected when the stress exceeds fy/2;the measurement precision of the surface stress is improved with the steel tube diameter increasing.Surface stress measuring and inner force identification of steel tube under tension（compression） and bending are practical and feasible by using blind-hole method,and the accuracy can meet the need of the engineering application.