建筑钢架构用聚氨酯胶粘剂的阻燃性能分析

建筑钢架构的阻燃性能要求较高,为此研究了建筑钢架构用聚氨酯胶粘剂的阻燃性能。将不同聚氨酯丙烯酸酯预聚体、多种有机阻燃剂、无机填料氢氧化铝以及纳米氧化锌等作为主要原料,将其以不同添加量混合,实现建筑钢架构用聚氨酯胶粘剂的制备,分别测试试样的力学指标、极限氧指数、垂直燃烧等级等参数,分析各主要原料添加量对聚氨酯胶粘剂阻燃性能的影响。实验结果表明:三种预聚体以1∶1∶1比例添加,试样可达到难燃烧等级,且剪切强度、硬度、极限氧指数各指标综合最优;单独添加15%、30%三聚氰胺(分析纯)(ME)、25%、30%三聚氰胺焦磷酸盐(MPP)、10%、15%磷酸三(2-氯丙基)酯(TCPP)可起到阻燃效果,将ME、TCPP、MPP以15%、15%、25%添加量复配,其断裂伸长率、拉伸强度分别比不添加阻燃剂试样增长18.1%、22.09%,损坏长度最小;氢氧化铝、纳米氧化锌添加量分别为45%、2%时试样阻燃性能最突出。

Design of Dissipative Braces for an Existing Strategic Building with a Pushover Based Procedure

The research presented in this paper deals with the seismic protection of existing frame structures by means of passive energy dissipation. An iterative displacement-based procedure, based on capacity spectrum, to design dissipative bracings for seismic retrofitting of the frame structures is described, and some applications are discussed. The procedure can be used with any typology of dissipative device and for different performance targets. In this work, the procedure has been applied, with both traditional pushover （load profile proportional to first mode） and multimodal pushover, to an existing RC （reinforced concrete） frame building. In the application, the buckling restrained braces have been used in order to prevent damages to both the structure and non structural elements. The use of multimodal pushover proves to be more effective than pushover based on single mode in case of medium rise RC frame building （higher than 30 m） but, once this building is retrofitted, and therefore regularized, with a bracing system, the difference between using monomodal or multimodal pushover becomes insignificant.