Test Research On Standing Performance Of Concrete After High Temperature And Fireproofing Safety Assessment Of Existing Building

Recently, fire becomes more and more serious with development of economics, acceleration of urbanization, construction of tall building and relative concentration of population. It has been one of the most danger, largest loss and highest frequency catastrophes. It concerns economic development and society stability to assess reliability of structures subject to fire scientifically and reinforce them properly. Many new subjects are put forth with practice of fire engineering on one hand and many new methods are provided with its research deeply on the other hand. So, it is necessary to establish a national standard to guide engineering practice, which should collect the newest research achievements.Central research institute of building & construction of MMI, cooperating with Dalian University of Technology, researched on performance of concrete subject to high temperature and some relative subjects for concrete 'structures with good resistance to fire. Based on establishment of Standard of Reliability Appraisal for Structure after Fire and funded by science research foundation of Central research institute of building & construction of MMI, following works have been done with corresponding tests.1. Fire science in domestic and abroad and assessment of concrete structure subject to fire suitabl e to our country were summarized. Research technical routine is put forth.2. More than 300 prismoid concrete specimens with calcareous aggregate were made. Three factors, temperature in fire, standing time and cooling type and cure methods after cool, were considered to simulate possible appearance in fire and after fire. Many test schemes were planned for different purposes.3. Regularity of some mechanics index such as compressive strength, constitutive relationship of stress to strain and modulus changing with temperature, standing time, cooling and curing process after cool were studied by test. Corresponding regressive equation was obtained with large quantity of data.4. Delayed stable strength was found in different temperature and standing time according to concrete compression test data, which is a relative lowest value. The most proper time for reinforcement after fire was discussed.5. Relationship between concrete compression strength and rebound and ultrasonic speed value was studied by test. Special regressive equation was obtained to predict concrete compression strength. Also, empirical regressive equation was got to predict the temperature acting on concrete structure.ill6. Regularity of concrete petrography changing with temperature, standing time, cooling and curing process was studied by X-Ray diffraction analysis. Microscopic mechanics relative to macroscopic phenomenon after fire was discussed.7. Regularity of Microscopic pattern in concrete after fire changing with temperature, standing time, cooling and curing process was studied by stereoscan test. It was summarized to predict temperature in fire based on microscopic structure subject to fire.8. Concrete compression strength was predicted by Artificial Neural Network (ANN) considered three factors, such as temperature, standing time and cooling and curing process after cool. Also it was predicted in different rebound and ultrasonic values. Fire resisting performance of concrete was studied and predicted.9. Nonline transient temperature field was analyzed for concrete-filled square steel tubular columns. Fire resisting limit of concrete-filled square steel tubular columns was discussed.10. Grading standard of safety assessment and assessment method of fire resistance for existing structure were studied and calculation model of fire risk was presented.