The calculation of theoretical value of elongation for prestressing tendons layout of various shape

According to prestress loss due to friction, several formulas that can be use to calculate pre-stressing tendon elongation are derived under the arrangement in straight line, circular curve or parabola layout in this paper, the solutions were proposed for different tensioning tendon and spatial pre-stressing tendon and we discussed the recurrent problems that existed in the calculation, especially when asymmetrical arrangement of pre-stressing tendon, calculating expressions are also obtained where is the point of stress balance (fixed point in theory) for prestressing tendons layout of various shape.