Accurate calculation and measurement method for elongation of pre-stressed strand of Bridges

Abstract

In the pre-stressed construction of bridge strands, tension stress is used as the control and strand elongation is used as the calibration and the elongation of strands directly affects the performance of the bridge structure. So, it must be very precise. In actual construction, due to inadequate grasp of basic theory by technicians, improper measurement methods or inaccurate selection of calculation formulas, neglecting the relationship between the actual elongation value and the tool/job clip withdrawal amount, resulting in the deviation between the actual measured value and the theoretical design value is beyond the standard, which is very unfavorable to the quality of the engineering structure. This article starts with the basic science theory, through numerical calculation and theoretical analysis, explains the work stress compensation retracting amount of the Work anchor and tool anchor, and the compensation stress calculation method due to the stress loss caused by the retraction. It shows the working principle of the pre-stressed equipment, and proposes and validates accurate calculation and measurement method of strand extension.