DUGi

Analysis and experimental measurement of losses in prestressed concrete : definition of a procedure

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Prestressed concrete has become a crucial part in the current architectural and civil engineering world. It is used to produce beams, bridges, floors … Due to the prestressing force these concrete elements can withstand high loads. The ability to cover larger spans than any other regular reinforced concrete parts has been a milestone in today’s engineering possibilities. To maintain this ability it is very important that the compressive stresses inside the element are controlled. When applying a prestressing force to a concrete element it is necessary to take into account that losses will occur, which will decrease the prestressing force. The measurement of these losses in on-site conditions usually is performed in a very elementary way. In this thesis a more accurate and efficient way to measure the compressive stresses and prestress losses inside the element is defined. The objective is to create an autonomous, automatic and remote data acquisition system. To supervise the stresses strain gauges will be attached to the prestressing cables. With the strain gauges the strain in the strand(s) can be measured. The strain is sent to a remote server through the acquisition system, where it can be used to analyse the stresses. First the state of the art is analyzed. The general idea where the problem will be defined and a solution is proposed will then be discussed, followed by the design of a special duct element created to protect the strain gauges. In the next chapter the design of the steel elements is discussed, which are needed to execute the tests. Finally the study, execution and analysis of the tests are described in the case study. To end a general conclusion is made and further research is proposed