Numerical analysis of the pretension deviations of a novel crescent-shaped tensile canopy structural system

• The pretension deviation may not be disregarded for a crescent-shaped tensile canopy structure.
• A numerical method is developed to calculate and evaluate the pretension deviation.
• Pretension deviations caused by geometrical errors vary with the tensioning schemes adopted.
• Distinct pretension deviation remains if only controlling the lengths of members.
• Effect on controlling pretension deviation validates a tensioning scheme.

The pretension deviation caused by two kinds of geometrical errors, manufacturing error of member length and installation deviation of anchoring joint, is investigated for a novel crescent-shaped tensile system applied as the canopy structure in Yueqing Stadium, Zhejiang, China. The deviation of anchoring joint is transformed into the length error of radial cable, and the member length error is assumed to yield Gaussian distribution. An analytical expression, which reflects the relationship between the member length errors and pretension deviations, is deduced. A different choice of active cables leads to different sensitivity matrix in this analytical expression, which indicates theoretically that the effect for controlling pretension deviation varies with the tensioning scheme adopted in the construction. A cable truss is employed as an illustrative example to investigate the validity of this method. According to the limit values of the two kinds of geometrical errors specified in China standards, the structural pretension deviations under five tensioning schemes are calculated for the crescent-shaped tensile canopy structure. The pretension sensitivity of each member category to the geometrical errors is analyzed by comparing the relative pretension deviations. The control effects on pretension deviations are also compared for these five tensioning schemes. The results indicate that distinct pretension deviations exist in the structure if only controlling the lengths of all members or the tension forces of ring cables during construction. Stretching the upper and lower radial cables and also controlling their tension forces can prominently decrease the structural pretension deviations. However, the pretension deviations of suspenders cannot be effectively controlled for any of the five tensioning schemes.