Contraction Of Steel Research Articles

Multi-stepwise thermal prestressing using a cover-plate in steel structures

This paper introduces an innovative prestressing method for steel structures utilizing a multi-stepwise thermal prestressing method (M-TPSM). The proposed prestressing method is founded on a simple concept of thermal expansion and contraction of steel. A cover-plate, a high strength steel cover-plate used as a post-tensioning member in this method, is heated by electrical heaters before it is attached to the main member. After the cover-plate is attached to the main member by using high tension bolts at several points or by welding, the electromagnetic induction heaters are removed, and the resulting contraction force of the cover-plate induces eccentric axial forces to the main member. In this study, a fundamental investigation involving analytical and experimental study is carried out to evaluate the feasibility of the M-TPSM for steel structures. Also, static loading tests were performed on the rolled beam specimens for assessment of the behavior of the steel beam prestressed with M-TPSM.

콘크리트 교량의 보강을 위한 온도 프리스트레싱 공법의 실험적 연구

Traditional external post-tensioning method using either steel bars or tendons is commonly used as a retrofitting method for concrete bridges. However, the external post-tensioning method has some disadvantages such as stress concentration at anchorages and inefficient load carrying capability regarding live loads. Thermal prestressing method is a newly proposed method for strengthening and rehabilitation of concrete girder bridges. Founded on a simple concept of thermal expansion and contraction of steel, the method is a hybrid method of external post-tensioning and steel plate bonding, combining the merits of two methods. In this paper, basic concepts of the method are presented and an illustrative experiment is introduced. From actual experimental data, the thermal prestressing effect is substantiated and the FEM approach for its analysis is verified.