Study On Evaluation And Repair Of Fire-Damaged Concrete Structures Quality

Fire usually brings greater damages to the structure of the reinforced concrete, but it can be used continuously by means of reconstruction and reinforcement. Only under seldom condition (such as the structure brings about serious thermal deformation and the component steel has been seriously bent etc.), it will be economical for dismantlement and reconstruction. Therefore, for the component parts and structures of the reinforced concrete after the fire, a reasonable evaluation to the damage extent of the component parts and structures should be made through the on-site detection and the necessary calculation and analysis, as well as the comprehensive evaluation of the performance of its excess force and the state of the force tolerance and then the corresponding tactics of reconstruction should be worked out and the specific measurements of reinforcement should be adopted.As soon as a fire breaks out in the building, the fire temperature will firstly be transmitted to the surface of the structural component parts by means of the thermal radiation, thermal convection and thermal conduction and then spread inside the components via thermal conduction. The development process of the indoor fire temperature and the study of the interior temperature field of the components as well as the study of the main technical data after the fire are the basis for the analysis of the structure after the fire and the evaluation of the damage extent of the structure and reconstruction and consolidation after the fire and at the same time it is one of the chief distinctions between the study of resisting the fire and the other studies of resisting the natural calamities (such as the studies of resisting the quake and the wind etc.).The mechanical characteristics of the steel and the concrete will be reduced in varying levels under the high temperature and after the high temperature and cause the resisting force of the structural components and the whole structure drop, and further affect the safety of the structure in and after the fire. To ensure the safety of the reinforced concrete structure in the fire and provide with the scientific foundation for the evaluation of damage and the reconstruction and consolidation of the structure after the fire, this article carries out a quantitative analysis to the attenuation of the resisting force of the components and the whole structure in and after the fire.The fuzzy comprehensive evaluation is an effective method adopted for evaluating the reliability of the structural quality of the building after the fire, preventing the blindness and subjectivity of the evaluation results and particularly in the complicated factors, reflecting effectively and precisely the actual circumstances. If the adoption of the on-site detection to determine the technical data and the fuzzy comprehensive evaluation to determine the reliability of the structure is a kind of the more precise way of evaluation, this is also the innovation and characteristics of this project. The effectiveness of the method has been set up and verified by fuzzy comprehensive evaluation of the actual circumstances of the fire happened on site of Shenyang Commercial City.The prediction of the remnant lifespan of the reinforced concrete structure after the fire is of great worth to the site. After some constructions got a fire which has been regarded not too serious and no treatment had been taken upon actually, this will affect very much the lifespan of the whole reinforced concrete structure. The prediction method is used not only for the fire, but also for the damage of the reinforced concrete structure caused by some other natural calamities. The prediction of the lifespan for the reinforced concrete structure after the fire is also put forward for the first time by this project.The measures taken for the reconstruction of the reinforced concrete components after the fire should be determined by the damage level and range of the components. The sticking of the carbon fiber to consolidate the repaired reinforced concrete components possesses the features of high intensity and high effect and the carbon fiber material has its superior physical dynamic features with its tensile strength of over ten times than that of the steel products. The features of its high intensity and high modulus can be used in the consolidation of the reinforced concrete structure to improve the bearing capacity and ductility of the structure so as to achieve the goal of high effective consolidation. Meanwhile, it possesses the features of corrosion resistance and endurance after the reconstruction and consolidation. The chemical feature of the carbon fiber material is stable and will neither react with the chemical materials of the acid-base salts, nor increase the dead weight and dimensions of the components. The carbon fiber cloth is light in mass, thin in thickness and the weight after sticking will not reach1.0kg/m2(including the weight of the adhesive). The sticking of about1.0mm in thickness will hardly increase the dead weight and dimensions of the components. It is a kind of more advanced technology of consolidation and reconstruction in China which can be widely used particularly for the consolidation of components after the fire.