A Study Of Pre-stress Strengthening T-shape Beam Carrying Capability Based On Model Test

With the development of our country, many various types of highway bridges, railroad bridges, highway-railroad dual purpose bridges, urban bridges and overpasses had been built. Because of the long period reiteration function of vehicle load on the old bridges, which had led to many inevitable flaws or damages in the bridge structure, and some of them may be already serious.The influence of reiteration function to changes of bridge carrying capability is unknown. Current design method of criterion cannot achieve this request satisfyingly. Therefore, further improvement to this method is indispensable.This paper conducts study of the extensively applied pre-stressed reinforced beam at present time based on consulting plenty of domestic and overseas research products, and the main work of test were carried out as follow.(1)Five pre-stressed concrete T-shape beam models were designed with conducting relevant fatigue test. Based on the experiment, this paper discovers the law of the pre-stress strengthening losings caused by reiteration function of vehicle load on the states of full pre-stressing concrete component and partial pre-stressing concrete component.(2)Through the static loading test on the beam with fatigue damage, ultimate load of model beam with different initial damage beam and relationship between the bearing rate and the average crack width by linear regression was obtained.This paper explains the finite element method of the concrete structure nonlinear analysis in detail through the introduction of modeling method of reinforced concrete, concrete failure criteria, material constitutive relation, crack model of concrete and so on. ANSYS, a finite element program, was used to make model of the pre-stressed concrete beam by separating entity in order to analyze the beam's whole process of stress and deformation from loading to destruction. Following results were obtained by comparing the experiment results with finite element model results.After all pre-stressed state of fatigue loading, the beam's ultimate strength decreased by about 8%; after A class pre-stressed state of fatigue loading, the beam's ultimate strength decreased by about 27%.Moreover, on fatigue tests, effective long-term loss of pre-stress was measured by using the self-made pre-stress loss measuring instrument. On the static loading test, to obtain a more precise result, the HJ series of concrete sensor was used to measure concrete crack width.