Research on Partition-Multi-Objective Equivalent Static Wind Load Method for Roof Structure

The roof structure has the characteristics of light weight, large span and low stiffness, which makes it sensitive to wind load. In this kind of structural design, wind load often plays a major control role. In addition, there are many members in structural joints, and many target responses are concerned. Consequently, the traditional single-objective equivalent method is difficult to achieve the equivalent of multiple responses.
In view of the uncertainty of the control points and the equivalent static wind load of the roof structure, a partition-multi-objective method is proposed in this paper. The partition is based on the roof structure shape and the average wind pressure coefficient of the measuring point. A small amount of partition fluctuating wind pressure is used as the basic vector of the load distribution. When the equivalent static wind load is calculated using the multi-objective equivalence theory, the equivalence of the target response can be ensured. However, the distribution of the equivalent static wind load may be unreasonable, and the static wind pressure in the local area may be far beyond the actual situation. Therefore, in order to ensure the reasonableness of the partition equivalent static wind pressure distribution, the weighting factor is introduced to determine the distribution of equivalent static wind loads by solving the minimum of constraint equation. In this paper, the wind vibration response calculated by the time-history method is assumed as the accurate value, which is compared with the vibration response calculated by the partition-multi-objective method to verify the calculation accuracy. Finally, taking the practical engineering of roof structure as an example, the equivalent response accuracy and applicability of the proposed method are analyzed.
Conclusionsare drawn as following:1) For the multi-objective equivalent static wind load of the actual roof structure, the multi-objective equivalent method without constraint conditions has the highest equivalent response accuracy and the lowest overall error. However, this method facing the problems of unreasonable extreme wind pressure, the wind pressure changes violently and intensively, which is not applicable to practical engineering. Therefore, constraint conditions should be introduced for the multi-objective equivalent equation. 2) After the constraint conditions are set for the multi-objective equivalent equation, the overall equivalent response accuracy is slightly lower than that of the unconstrained multi-objective method, but the errors are acceptable. The maximum equivalent wind pressure is effectively constrained, and the wind pressure changes gently. In the weighted constraint multi-objective method that setting the critical equivalent objective, the equivalent response of the critical objective is in good agreement with the wind vibration response, and the distribution pattern of equivalent wind pressure can be further improved. 3) In practical application, the distribution coefficient can be used to constrain the partition fluctuating wind pressure. Generally, the peak factor is taken as the constraint range of the distribution coefficient, or the constraint range can be appropriately extended to ensure the equivalent response accuracy. The results show that the basic vector of this method can well describe the wind field characteristics of the roof. In addition, the equivalent static wind load distribution obtained by this method is reasonable, and the change of wind pressure in the partition is uniform and continuous. In conclusion, the equivalent response is high, and it is convenient for engineering application.