Study On Behavior Of Steel Tube Short Columswith High Water Material-filled Under Axial Compression

High moisture material，as a new material and has been poorly studied at domestic and abroad,is of low price and high performance. It has many advantages such as its filling with high water ratio, rapid hardening and strengthening,high compactness and excellent pumpability,etc. Nowadays, domestic and international researches about this material mainly focus on raw material、characteristic、 mechanical property and application. As been seen in amounts of domestic and international studies, high moisture material has low strength, and been mainly applied in mining engineering. This paper investigates the strength of high moisture material, aims at applying high moisture material in structural engineering, and provides references for future studies. Concrete-filled steel structure is a composite structure with many merits, filling this high moisture material in steel tube,which combines the advantages of steel tube and high moisture material,improves the strength of the composite structure and shortens the hardening period. This composite structure is of high economic efficiency and high early strength.Based on previous studies, this researched can be divided into two parts. In the first stage, this paper studies the performance and mechanical property of the high moisture material with sand and cement in various proportions. In the second stage, the high moisture material has been applied in steel tube to make a composite structure, then some preliminary experimental investigations towards the mechanical property of the composite structure have been conducted.Study begins with mixing high-water material with sand in different proportion to investigate how different sand content effects on the mechanical properties of high-water material and to analyzes the influence of sand contend, water/cement ratio and cure age on high-water material comprehensively.In the next stage, by comparing high-water material with concrete,425cement in different proportion are used to replace different ingredient of high-water material. Then experiments on the influence of cement substituting clinker, plaster with clinker and plaster on the mechanical property of material are respectively performed in order to analyze the reaction mechanism of high-water material.After that, high-water material is penetrated into steel tube to form a structure with high wate material.Axial compression tests on the short column of the composite structure are performed to study the failure modes of the specimens, ultimate bearing capacity and deformation features. The influences that core material, the water/cement ratio of core material and thickness of steel wall have on the mechanical property of specimens are comprehensively analyzed. Through regression analysis towards test results, numerical methods about the ultimate bearing capacity of the composite-type short column is obtained. This paper also compares this numerical method with methods in specifications for concrete-filled steel tube.Eventually this paper gives direction for further research and content.