Study On The Infuence Which High-temperature Exert On The Mechanical Properties Of Concrete And The Bearing Capacity Of Segment

The fire endangered the safety of human life and property seriously, and as population gathers to the city gradually, the damage caused by fire in the future may be more serious day by day. Concrete is the largest and most widely used building materials in the world; its fire-resistance performance directly decides whether the structure could keep intact and steady in the fire-disaster. The research work of this article is just based on this idea. Two parts are included: First, the mechanical performance of concrete and steel after and under the fire is studied; second, some simple calculations to the load capacity of model reinforced concrete segment have been done, and besides, a test is designed to compare with calculation.In the process of researching on the performance of concrete under and after high temperature, a large number of relative papers are reviewed, and besides, 26 cubical concrete specimens are designed for experiment. Based on the data from experiment, some formulas are suggested for calculating the compressive strength, limit strain and elastic modulus at high temperature. And the material parameters for calculating the bearing capacity can be provided.Because chemical composition and micro structure in steel are comparatively steady, the mechanical performance of steel bar at elevated temperature is more steady than that of concrete. In this article, some research findings about the performance of steel bar under high temperature are summarized. Furthermore, some advices are provided for calculating the strength parameters of steel bar at elevated temperature.There are three main stages in the calculation of bearing capacity of reinforced concrete structural member. First, calculate the temperature field; second, convert the non-homogeneous section into homogeneous section; third, calculating the key point on the envelope line of bearing capacity. And suppose that the curve between the two key points is a straight line, so a comparatively precise and safer result can be gotten. In the final part of the article, the bearing capacity of model segments are tested, the experiment result is coincident with that of the calculations.