بررسی افت لرزه ای ساختمانهای بلندمرتبه مجهز به دیوار پرده ای
Abstract
1- Introduction
2- Material and methods
3- Calculation: Finite element modelling scheme
4- Results and discussion
5- Conclusions
References
Abstract
The dynamic interaction between glazed curtain wall stick systems and modern high-rise mega-frame buildings is investigated. In the present paper, four moment resisting frames (MRFs), consisting of thirty- and sixty-storey steel-based prototypes, are designed according to European standards: internal concentrically braced frame (CBF) core, outriggers and belt trusses are adopted to limit inter-storey drift and second order effects. Force-displacement relationships are derived from available full-scale test data performed on non-structural aluminium façade units. Therefore, 3D finite element (FE) models are developed to interpret the physical phenomena involved in façade dynamics: as a result, equivalent 1D nonlinear links are calibrated to simulate these phenomena independently. Nonlinear time history analyses (NLTHAs) are executed to investigate the potential combination of stiffness and strength of such hybrid systems, i.e. achieved through the integration of glazed curtain walls on the MRF lateral force resisting system (LFRs). Local and global performance will be shown in terms of inter-storey drifts and displacement peak profiles, forces and percentage peak variations, highlighting static-to-seismic load ratios in critical members and the sensitivity to the structural height. Conclusions point out that, even if accurately designed according to current standards, the façade omission from the seismic analyses of high-rise structures may lead to a crucial underestimation in the dissipation capacity of the building.
Introduction
Tall buildings have become the symbol of national economic welfare, restyling skylines and facing the scarcity of land, emphasized by the growing need for business and residential areas. A deeper insight on high-rise systems, innovative computational techniques, as well as high-strength and smart materials have led to exploration beyond traditional structural designs, posing novel challenges for civil engineers [1–3]. For instance, as the building height increases, longer periods and higher mode effects become dominant factors, demanding stiffness and stability design criteria instead of strength requisites [4,5]. Moreover, passive and active dissipation properties represent a supplementary principle in controlling the structural behaviour toward human comfort, safety and cost-effectiveness under lateral actions [6]. However, due to the broad nature of Codes, these necessarily reveal shortages in practical tools for structure-specific design [7–9]. Hence, ad hoc tools are required to predict and ensure the achievement of target performance levels. In fact, traditional approaches do not normally conduct toward an optimum in high-rise design: since uncertainties are commonly treated introducing simplifications in numerical modeling and analysis techniques, balancing the lack of confidence with weight coefficients that usually satisfy project requirements against economical needs [7,9]. Therefore, the use of scaled shaking table and wind tunnel testing, together with more conventional research tools such as finite element (FE) simulations, have been extensively adopted in dynamic response assessment [10,11]. Recently, the curiosity on non-structural elements has increased significantly, stimulated by the related reparation cost that commonly represents the highest investment, as highlighted in Fig. 1 and [12–15].