Numerical study of Strengthening of RC Deep Beams using Post-Tensioned CFRP cables

نوع: Type: thesis

مقطع: Segment: masters

عنوان: Title: Numerical study of Strengthening of RC Deep Beams using Post-Tensioned CFRP cables

ارائه دهنده: Provider: Soroush Anbarian

اساتید راهنما: Supervisors: Freydoon Rezaei (Ph. D)

اساتید مشاور: Advisory Professors:

اساتید ممتحن یا داور: Examining professors or referees: دکتر مصطفی مقدسی - دکتر محمد شوشتری

زمان و تاریخ ارائه: Time and date of presentation: November, 2020

مکان ارائه: Place of presentation:

چکیده: Abstract: Nowadays, many of RC structures have been subjected to depreciation so that they are losing their design capacity, serviceability and safety; therefore, engineering measures and intervention is needed promptly to rehabilitate them. The rehabilitation of structures is not the only aspect of repairs, but in the projects that include user changes and capacity increase of the structure is also needed. Deep beams are one of the most important RC members that need to be rehabilitated. The purpose of rehabilitating deep beams in this study was to increase their load - bearing capacity by a strengthening method called; externally unbonded post-tensioning. Externally unbonded post-tensioning is a way of pre-stressing a RC member in which, the pre-stressing cable or rod is connected to the outer surface of the member at anchorage points, after the establishment of the structure. In this research, deep beam post-tensioned with deviated CFRP cables was analyzed and the results of it were compared to deep beam post-tensioned with straight CFRP rods. In order to analyze the post-tensioned deep beams in this research, two methods namely; finite elements and strut and tie model were selected. Help was taken from a numerical analysis software called; "ABAQUS", because of the complexity of finite elements computations. In all steps of the post-tensioned deep beams analysis, design and control requirements were carried out by ACI 318 - 19 building code for structural concrete. In order to interpret and evaluate the results obtained from the analysis of post-tensioned deep beams, processed output data are presented in; bivariate diagrams and graphic images. According to the obtained results, it must be acknowledged; while strengthening the deep beams, any amount that the load - bearing mechanism is approached to the shear - pressure mechanism, high shear capacity along with low ductility is provided. Now if the load - bearing mechanism tends towards the bending mechanism, lower shear capacity with high ductility is achieved. Accordingly, the deep beam post-tensioned with deviated cables contains elevated ductility whereas, deep beam post-tensioned with straight rods contains elevated shear capacity. At the end of this thesis, the results obtained from post-tensioned deep beams analysis are compared to a similar lab study to determine the validity of the data. The comparison of shear capacities achieved from; analysis of the deep beams using finite element ABAQUS modeling and strut and tie model, to measured experimental capacities, demonstrates the accuracy and conservatism of the two chosen methods for estimating the shear capacity of deep beams. Key Words: RC Deep Beam, Strengthening, Externally Unbonded Post-Tensioning, Strut and Tie Model, ABAQUS software

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