X型超高层建筑的三维风荷载及风振响应

3-D wind load and wind-induced response of X-shaped tall building

以某X型超高层建筑为工程背景,研究了该超高层建筑顺风向、横风向以及扭转风荷载系数沿高度方向的分布规律.以质量和刚度相同、动力特性相近为原则使用简化的自由度缩聚模型代替结构精确有限元模型,计算结果显示结构位移与加速度响应均以一阶模态响应为主,该模型代替精确有限元模型能够满足工程计算需要.对质量中心和刚度中心重合的结构,扭转加速度响应在合加速度响应中占有的比例较小,结构在3个方向上振动的耦合程度不高.提出的合成位移投影方法计算出的沿坐标轴方向的风振系数能够保证X和Y方向最大位移与合成位移最大值的同步性,并考虑了横风向风振的影响略大于顺风向风振系数.

Taking a X-shaped tall building for example, the distribution of 3-D wind load model was studied. Relationship between average value and turbulence value of along-wind load, across-wind load and torsion wind load was also analyzed. Simplified calculation model were substituted for precise finite element model on the premise that the quality and stiffness of two models must be the same and kinetic characteristic must be exactly approximate. It is proved that tensional acceleration response only takes a small part in composition of acceleration response and structural vibration at three direction couples little on account of superposition of quality center and stiffness center. Resultant dis- placement projection method proposed in this text which can ensure the synchronization of maximum displacement projected to X and Y axis is used to calculate wind load factor along X and Y axis. In view of the influence of across-wind excited vibration, the calculated result is a bit larger than wind load factor only taking along-wind vibration into account.