高烈度区地铁上盖结构层间隔震设计研究

以西安某地铁上盖项目为工程背景,对高烈度地区采用下部框架+隔震层+上部剪力墙体系的地铁上盖结构设计的关键技术要点进行介绍.本项目主体结构存在大底盘多塔、刚度突变、扭转不规则、承载力突变等多项超限;同时存在首层为软弱层和薄弱层、隔震层下一层框架刚度难以满足对隔震层上一层剪力墙结构的嵌固要求、楼面超长、裙房框架和地基基础的抗震设计要求高等众多设计难点.针对以上结构超限项和设计难点,在合理调整结构体系、采用层间隔震技术减小上部结构地震作用的基础上,对盖上盖下各部分结构构件进行抗震性能化包络设计,并结合罕遇地震动力弹塑性分析结果对结构的抗震性能进行了详细的分析与评价.结果 表明,在高烈度地区应用上述结构体系的地铁上盖项目技术可行,采用隔震技术结合构件性能化设计等技术措施可有效保证结构的抗震性能.     

首开万科中心超高层结构抗震设计

大兴首开万科中心为超高层建筑,建筑基本形态呈切角三角形,结构抗倾覆能力相对较弱,角部设置跨度约15m的斜拉式观景平台。结合工程特点,对超高层结构设定合理抗震性能目标,针对该目标提出抗震措施及抗震构造措施。通过调整合适的结构刚度,有效降低核心筒墙体在设防地震作用下的拉应力峰值。对悬挂结构关键部位进行水平及竖向的承载力专项分析,并考虑防连续倒塌要求。结果表明,结构在各地震水准下满足规范要求,结构安全可靠。     

复杂超限高位大跨连体结构设计

项目是由左右两塔与高位大跨连廊组成的三位一体的复杂高层建筑。连体结构部分的位置高、跨度大,且两侧塔楼与中间连体结构层高不同,有局部错层,同时因主体结构和连体部位采用两种不同类型材料,给结构设计带来了较大的挑战。设计采用了多项有效抗震技术措施,详细分析了连体结构、高位大跨连廊的受力性能,通过振动台模型试验验证了所采取的抗震措施的可行性,工程设计顺利通过超限建筑专项审查。     

基于单元应变模态差的网架结构损伤诊断研究

对具有一定程度损伤的网架结构来说,常规的结构有限元分析或实验模态分析得到的位移模态和频率难以有效地反映结构的损伤状况。为了提高诊断效率与诊断结果的可靠性,根据空间杆系结构的受力特点,利用两节点空间铰接杆单元有限元法,由节点位移模态推导出单元应变模态,提出采用结构损伤前后的单元应变模态差作为网架结构损伤定位的识别指标,并以损伤单元应变模态的差值大小确定损伤程度。通过对一个典型网架结构的数值模拟研究表明:该方法能够在低阶模态条件下,有效识别网架结构不同位置和程度的局部损伤;且在一定噪声水平下具有较强的鲁棒性,适用于实际观测条件下的网架结构损伤定位。     

Test research and computer simulation analysis of construction state during form finding for suspen-dome system

A novel construction method without scaffold work called as assembly-prestressing form finding loop by loop is presented.Based on the theory of finite displacement,the cycle-forward analysis method is presented for its construction calculation,which adopts the finite element method of generalized geometric nonlinearity combined with the application in the real construction process.By means of the combination of the forward analysis according to real construction sequence and the cycle iteration according to the initial strain increment method of cable force adjustment,the influence of the structural geometric nonlinearity and the loss of prestress are taken into account due to prestressing of tendons in turn and so on.If the initial cable forces derived from the method were used for construction,expected cable forces and shape could be assured easily.Simulation analysis achieved real-time tracking and controlling of the construction status.Finally,according to the procedure and parameters in simulating,a model experimental research on the stage of form finding(namely prestressing)was carried out for suspen-dome structure.The feasibility on the assembly-prestressing form finding method loop by loop was testified.The cycle-forward analysis method was established and numerical simulation was performed,and the results show that it was useful for the design and the construction of similar suspen-dome structure.