Experimental Study On Pore Pressure Of High Strength Con Crete Under High Temperature

High strength concretes are liable to burst in the fire, and the high temperature burst is a kind of instantaneous destruction phenomenon which will have a serious impact to the bearing capacity of structures. The paper analyzes several kinds of causes and mechanisms about high temperature burst of high strength concrete. Meantime, design and conduct test on the mechanism of pore vapor pressure, measure the pore pressure change rule and the changing rule of the temperature field with time under high temperature inside the concrete pore structure, and analyze the influence of pore steam pressure to high temperature burst of concrete. Specific content is as follows:1. Summarize the current research status of the concrete temperature burst mechanism, analyze several methods about high temperature burst test of concrete, and design the test targets and test methods.2. Design the steam pressure test device of pore inside concrete under high temperature, measure the pore pressure and the rule of temperature field changing with heating time inside the block of high strength concrete, polypropylene fiber concrete block, steel fiber reinforced concrete block and rubber concrete block under high temperature, and analyze the temperature burst mechanism of concrete, the mechanism of pore steam pressure and the improvement of high temperature burst when fiber is added in the high strength concrete according to test data.3. Use the finite element method to simulate the temperature field change inside concrete block under high temperature, and analyze the influence of temperature field to the mechanism of high temperature burst pore steam pressure according to test data. Establish thin wall spherical pore model with the representative volume ele-ment(RVE), simulate the mathematical model of pore pressure in spherical pore, and explain the burst caused by the pore pressure with mathematical method.