Experimental study on critical wind velocity of a 33-meter-span flexible photovoltaic support structure and its mitigation

Flexible photovoltaic (PV) modules support structures are extremely prone to wind-induced vibrations due to its low frequency and small mass. Wind-induced response and critical wind velocity of a 33-m-span flexible PV modules support structure was investigated by using wind tunnel tests based on elastic test model, and the effectiveness of three types of stability cables on enhancing the critical wind velocity of the flexible PV modules support structures was carefully examined. First, an elastic test model of the flexible PV modules support structure was designed and manufactured. Second, a series of wind tunnel tests based on the elastic test model were carried out to obtain the wind-induced responses of the 33-m-span PV modules support structure. Third, three types of stability cables (T1, T2 and T3) were installed on the test model, and a series of wind tunnel tests were carried out to examine the effectiveness of the three types of mitigation countermeasures. Finally, the wind load factor was discussed by using the displacement time histories measured from the wind tunnel tests. The results show that 180° and 0° are the two most unfavorable wind directions, and the critical wind velocity is only about 18.5 m/s for the deformation threshold of 1/100 span. The critical wind velocities for stability cables T1, T2 and T3 (1/100 of the span) are respectively 24.6, 29.3 and 36.7 m/s, which are significantly higher than the value without stability cable (18.5 m/s). The wind load factor at the windward side under wind directions of 0° and 180° are respectively 1.56 and 1.30 for the test case with stability cable T3.