一前言我国采用离心环形预应力钢筋混凝土电杆建设送电线路已有近二十年的历史,节省了大量的钢材与建设资金,但美中不足的是预应力电杆在运行中出现较多的纵向裂缝,各地电力生产部门反映较为强烈.造成这种情况的原因是多方面的,除制造、运输、施工、运行等原因外,在设计时所取预应力过大,电杆混凝土在未承受工作外力以前,由于钢筋预应力传给它的预压应力σ_h值已超过允许值,使电杆混凝土早已产生微裂缝.投入运行后,大气与地下水中的有害介质沿着微裂缝侵入杆体内部,渐渐导致构件破坏.在预应力钢筋混凝土构件发展过程中,世界各国曾走过弯路.开始多采用“全部预应力”或“有限预应力”构件,由干施加预应 A foreword China has adopted centrifugal annular prestressed reinforced concrete poles to construct transmission lines for nearly two decades. It has saved a lot of steel and construction funds, but the fly in the ointment is that prestressed poles appear more longitudinally in operation. The cracks are reflected in the power production departments around the country. There are many reasons for this. Except for manufacturing, transportation, construction, and operation, the prestressing force is too large during design, and the pole concrete does not work. Before the external force, the pre-compression stress σ_h value transmitted to it by the steel bar prestressed force has exceeded the allowable value, so that the electric pole concrete has already produced micro-crack. After the operation, the harmful medium in the atmosphere and groundwater penetrates into the rod body along the micro-cracks and gradually Lead to the destruction of components. During the development of pre-stressed reinforced concrete components, countries around the world have walked through the detours. We began to use the “all prestressed” or “limited prestressed” components, and the pre-stress applied by the dry.