Elastic Seismic Analysis Of RC Frame-shearwall Structure With A Steel Tower Atop Involving Non-classical Damping

With the development of Television, broadcasting and communication, especially the development of the mobile communication, more and more steel towers have been built on the top of reinforced concrete constructions. The damping ratio of steel structure and reinforced concrete structures is different. A steel tower atop a reinforced concrete building composes a non-proportional damping system. The dynamic responses of the system can't be obtained by classical modal superposition method, as its result in a coupled equation group. The dynamic analysis of this kind of system by direct integral method is time-consuming. The non-classical modal superposition method is used for the elastic earthquake response analysis of this system in this paper.Furthermore, a new kind of wall element is presented in this paper and some interrelated programme is also developed for more accurate analysis of shearwall structure. This kind of wall element is made up of a kind of membrane element and a kind of plate element, neglecting the coupling between the two kinds of elements. The corner nodes of the membrane element have rotation freedom in the plane. The wall element has all six freedoms and can be interlinked with any other members. The wall element has some advantages. First, it has high accuracy, namely one element call imitate one span wal1. Second, it can deal with the holes on the wall easily. Besides, it can cooperate with beam's elements very well. It makes up the deficiencies of the other elements and suited to analyzing shear-wall structures, especially the finite element analysis of the high building.The accuracy of the programme related to the wall element is demonstrated in this paper. An example, referring to a reinforced concrete building with a steel tower on its top, is calculated with equivalent damping ratio and real damping ratio. Some comparisons between two kinds of damping ratio are performed and indicate that the result with equivalent damping ratio will tend towards waste of resource or insecurity. The real damping ratio should be used to analyzing the constructions made up of materials of different damping ratio.