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Rehabilitating damaged concrete elements can be called a more attractive alternative to rebuilding and demolishing existing structures based on the present national economic climate .In certain projects retrofitting is the only option because of budgetary restrictions that bridge owners are facing (1)(2)(3).
Up to now based on availability of materials, cost, level of damage and environmental condition several methods of repair have been developed. These methods include attaching external plate by using bolting or epoxy, bonding external reinforcement, chemical grouting, Portland cement grouting (4) (5), resin based repair mortar, high flow concrete, jacketing technique, patch repair, low slump dense concrete, Fiber Reinforced Polymer (FRP) and fiber shotcrete (2) (6) (7).
This study is performed to provide an alternative method for retrofitting the flexural bridge elements by attaching a layer of UHPC shell to damaged areas. This method may provide a predictable behavior for the beam and significantly increase the flexural capacity of the beam in allowable serviceability criteria. Some of the advantages of using UHPC shell in retrofitting include, having high tensile strength and shorter development length compared to regular concrete. The expected outcome of this project is a design guideline for retrofitting the beam with UHPC shell.
A comprehensive development plan and procedure is proposed to achieve the objectives of the research. The research plan is divided into eight tasks to provide a logical sequence of development.
Task 1: Literature Review: A detailed literature review on different aspects of the research, such as properties of UHPC, current method of retrofitting, and finite element analysis, will be discussed. This work will continue to ensure that latest research results are included in the literature search.
Task 2: First Testing of the Proposed UHPC shell (Feasibility Study): three test specimens were tested first one without any damaged, and second one with damage and third one retrofitted with UHPC without any preparation of beam surface.
Task 3: Second Testing of the Proposed UHPC shell: Six test specimens were constructed to check the effect of different thickness of the shell in sides, using mechanical connection and preparation of beam surfaces with sand blasting
Task 4: Third Testing of the UHPC Shell: Four test specimens were constructed to check the effect of adding rebar to the damaged area and decreasing the length of cut rebar compering to the length of retrofitted portion.
Task 5: Numerical Investigation: The numerical analysis is perform using ATENA finite element software. By simulating the previous experimental tests, the effect of different parameter will be evaluated and next matrix of test specimens based on productivity of the idea will be developed.
Task 6: Forth Testing of UHPC Shell: Based on numerical model a test specimen of a deck will be constructed and tested.
Task 7: Data Reduction and Interpretation: The test data will be reduced and interpreted. This task will specify general behavior and the effect of some parameters of the UHPC shell.
Principal Investigator (PI): Dr. Atorod Azizinamini
Research Assistant: Alireza Valikhani