Examination And Evaluation Methods Of Post-fire Concrete Girder Bridges

Nowadays, the Infrastructure construction of roads and bridges has a rapid development,not only the bridges have a high proportion in highways, but also they are cononcrete beambridges. Followed by various types of bridge disasters, the fire disasters bring about a veryserious threat on the structural safety of the bridge, there is even a risk of causing even bridgecollapse. Therefore, it is necessary to the extent of damage the bridge structure for systemanalysis and research.As a Western-Project topic "Girder bridge fire detection and evaluation TechnicalGuide" part of this article, summarizes the high temperature mechanical properties of thematerial, fire temperature and the test methods to detect material strength after fire in thecourse of fire systematically;offer evaluation of the technical condition of the concrete beambridge after fire.Firstly, combined with relevant research results at home and abroad, summarized themechanical properties of the concrete materials, ordinary steel and prestressing steel in theprocess of fire. Compared with the mechanical properties of the concrete materials, ordinarysteel and prestressing steel in the process of fire proposed by Various scholars at home andabroad, the relevant norms,and analysis to determine the required mechanical index applicableto the bridge of reinforced concrete beams, including strength, elastic modulus and stress-strain constitutive relationship.Secondly, based on the methods of the existing relevant fire of fire temperature, concretestrength, the strength of ordinary steel and prestressing tendons effective, analyze thecharacteristics and applications of various detection methods.Finally, based on the evaluation system and method of calculation in current《Standardsfor Technical Condition Evaluation of Highway Bridges》（JTG/T H21-2011）, The bridge inaccordance with the common form of the upper structure is divided into these kinds:reinforced concrete slab bridge, prestressed concrete girder bridges, reinforced concrete beambridge rib, ribs prestressed concrete girder bridges, reinforced concrete and prestressedconcrete box girder bridge box girder bridge. When the damage Beam Bridge, substructure,deck department of each component, component are evaluated., on the basis of the originalevaluation of the project adds damage and fire damage evaluation of projects relatedcomponent part of the fire: after the fire strength of concrete, reinforced strength after fireafter fire effective prestressing tendons, tendon after fire spalling leak case, after the fireburned area members, the fire burning after the concrete bridge deck concrete depth and firedamage, etc. Members of the bridge fires burned in accordance with section and not bepenalized were partially burned, put the points situation into two parts formula finally, andcalculate the component’s technical condition score and rating.Application cases show that after the fire of bridges the technical condition evaluationmethod is easy to implement concrete in this study, make assessing the technical condition ofthe bridge is more targeted after the fire.