Interstorey drift

The variability of the wind load and model has the most significant influence on the interstorey drift of the budding. A variability of the permanent load G, wind load W, soil stiffness K and model stiffiiess E are important for the stress values in core wall. 

The main experimental results, for both positive and negative load action, are reported in Table 14.1. The maximum shear recorded on the column, Vcmax as well as the relevant drifts have been initially evaluated. Top colunui interstorey drift has been computed as the ratio between beam tip displacement (total displacement... 

In examining Figs. 17.9 and 17.10 it can be observed that there is a steady decrease of the inter-storey shear from about 1,000 kN at the 1st storey to about 400 kN at the top storey. What can be also observed is that while the interstorey drift at the 1st storey is about 20 mm, the interstorey drift for the upper three floors is on the order of 30 mm, which shows the influence of the larger stiffness of the RC... 

Fig. 17.9 Test at 0.25g acceleration (a) 1st storey interstwey drift, (b) 2nd straey interstorey drift...

Deformation limits are expressed herein in terms of interstorey drift ratios that should not surpass predefined limit values, even though other deformation measures... 

It is generally accepted that interstorey drift can be used to determine the expected damage. The relation between the drift limit ratios with the damage state, employed... 

Performance level Damage State Interstorey Drift (% ... 

The above expression is obtained by best fit of known Pi 0>0i) pairs. These pairs correspond to 2, 10 and 50 percent in 50 years earthquakes that have known probabilities of exceedance Pi. The corresponding maximum interstorey drift limit values 0i, for these three earthquakes, are obtained using the pushover analysis. According to Poisson s law the annual probability of exceedance of an earthquake with a probability of exceedance p int years is given by the formula ... 

Regular Building Peak Interstorey Drifts under DBE... 

The aims of the chapter are to find the optimal location of VE dampers and to determine their optimal parameters. Several objective functions, which are minimized, are taken into account. One of the objective functions is the weighted sum of amplitudes of the transfer functions of interstorey drifts, evaluated at the fundamental natural frequency of the frame with such dampers. Another objective functions are taken as the extreme displacement within the structure or as the extreme bending moment in the supporting columns. The optimization constraints are formulated, based on the properties of dampers. The... 

The weighted siun of amplitudes ofthe transfer functions of interstorey drifts, evaluated at the fundamental natural frequency ofthe frame with the dampers... 

The vector H (A)of the frequency transfer functions of interstorey drifts can be calculated from the following formula ... 

The optimal damper distributions in buildings are found for various objective functions. The weighted sum of amplitudes of the transfer functions of interstorey drifts and the weighted sum of amplitudes of the transfer functions of displacements evaluated at the fundamental natural frequency of the frame with the dampers are most frequently used as the objective function. The optimization problem is solved using the sequential optimization method and the particle swarm optimization method. Several numerical solutions to the considered optimization problem are presented and discussed in detail. 

Fujita, K., Yamamoto, K., Takewaki, I. (2010b). An evolutionary algorithm for optimal damper placement to minimize interstorey-drift transfer function in shear building. Earthquakes and Structures, 1, 289-306. 

More recently, Lavan and Dargush (2009) examined a multi-objective seismic design optimization in which the maximum interstorey drift andmaximiun acceleration were considered as the primary control parameters. The multi-objective problem was formulated in Pareto optimal sense (Pareto 1927) and a genetic algorithm based approach was adopted to identify the Pareto front. The endresultofthis multi-objective optimization is a family of Pareto front solutions providing the decisionmakers with an opportunity to understand the tradeoff between the drift and acceleration. 

Damping system may be used in addition to the SFRS in order to meet interstorey drift limits and it may be located external or internal to the structure, while it shares or not the members of SFRS. In Fig. 4 is illustrated a SFRS consisting of one bay moment resisting frame (MRF) and a damping system composed of diagonal braces with installed FDs. The FD system is located independently to the MRF system. 

Calculate the demanded slip force and size the in-line brace by employing simplified methods (e.g., the equivalent static force procedure). Then, the demanded peak interstorey drift (e.g. linear dynamic analysis methods) should be evaluated. 

To evaluate the seismic response of structures equipped with friction-damped braces, the following parameters should be investigated interstorey drift, lateral deflection, and residual interstorey drift. 

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