Wind-resistant Structural Optimization Of A Super-tall Building Considering Wind Direction And P-Δ Effects

Wind loads have increasingly become one of the key loads in the procedure of structural design with the super-tall buildings have becoming taller. The aerodynamic measures, increasing the damping device and optimum structural is adopted to improving the wind-resistance of super-tall buildings. Wind-resistant structural optimization of super-tall buildings is refers to adjust the size of structure members to minimize the cost of the structure on the premise of the structure meet the strength, stiffness, stability, comfort, construction requirements, etc. Super-tall buildings have a complex stress state and need lots of material, there have been literature shows that a complex tall building cost decreased a lot through structural optimization. Therefore, the work presented in this study would be great of theoretical and practical significance.At present, studies on structural optimization of super-tall buildings stay in the stage of theoretical research. The design load are calculated based on the load code that without considering the influence of wind direction and P-Δ effects. And most of the illustrative examples is too simple and idealized, there are only rectangular section. However, the actual super-tall buildings is extremely complex that always contains variety of cross section type, such as concrete-filled steel tube, I-section, box section, etc. But there are few literature reported the displacement formula by the optimization design variables of these section type. The gap between the theoretical studies and actual demands caused relevant optimization theory is difficult to apply in practical engineering. In order to solve the problem of the above mentioned, the equivalent static wind theory and optimum structural theory was apply to this thesis for wind-resistance design of super-tall building. Our works is listed as follows:1. The influence of wind speed reduction on wind-induced response have been studied. Frequency domain method and newmark-β method was to calculate the displacement response, acceleration response and equivalent static wind loads of super-tall buildings. The results indicate the necessity to consider the wind speed reduction of optimize structure design.2.Formula of geometric stiffness to analyze P-Δ effects is deduced. The newmark-β method was to calculate displacement response, acceleration response, the base overturning moment and equivalent static wind load of super-tall buildings considering P-Δ effects. The results show the necessity of considering the impact of P-Δ effects when analyze the wind-induced vibration response.3.Formula to solving displacement of rectangular section, I-section and box section is deduced based on principle of virtual work. The correctness of these formula are verified through an example, a 30-story frame structure comprises rectangular section, circular section, box section and I-section.4.A 103-story super-tall building of frame-core tube structure is taken as an example to show the procedure of structural optimization. Each structure-member’s sectional dimensions is selected as design variables, the total material cost is selected as the optimization objectives, and the drift and the story drift on y direction of structure is selected as constraint optimization. And the iterative process of sectional dimensions and cost, the change of constraint optimization are given in article. After optimization, the total cost of the structure has decreased 20.56%.