A Study on the Existence of an Optimal Distribution of Stiffness over the Height of Mid-to High-Rise Buildings to Minimize the Seismic Input Energy

2009 ◽  
Vol 10 (1) ◽  
pp. 45-51 ◽  
Author(s):  
Farzan Haddad Sha ◽  
Mahmood Hosseini
2013 ◽  
Vol 275-277 ◽  
pp. 1184-1189 ◽  
Author(s):  
Xiao Nong Duan ◽  
Neng Tang ◽  
Xue Ting Chen ◽  
Zhu Juan Yang

It was optimized that the lateral stiffness of an under-designed super high-rise building located in 0.30g seismic fortified regions, with 58 stories above the ground and 235.80 meters total structural height. By having adequately adjusted the wall thicknesses of the core-wall and the cross sectional dimensions of the frame columns, a more reasonable structural scheme was obtained. It was then discussed the suitable numbers and heights of the strengthening stories set for controlling the building’s story drifts. Finally, it was explored that the efficiency of seismic input energy dissipation via viscous dampers installed at the right places of the structure.


2004 ◽  
Vol 04 (02) ◽  
pp. 197-221 ◽  
Author(s):  
RAJEEV DUA ◽  
A. K. JAIN

The response of a structure to a seismic activity depends on the characteristics of the structural system and the seismic activity. To improve the seismic response of a structural system, it is bifurcated into two subsystems: a flexible one, catering to the primary function/occupancy of the system and a stiff one, taking care of the lateral strength requirements and housing major services of the system. Low stiffness associated with large mass in the flexible subsystem results in shifting of natural periods of the system to zones of low seismic input energy. The difference in lateral stiffness of the two subsystems results in differential response, which is utilized by placing floor-level links between the two subsystems; these links absorb and dissipate a substantial part of seismic input energy leading to a minimal structural distress. Three types of structural systems, viz. conventional system, seismically bifurcated system with rigid links (SBS-RL) and seismically bifurcated system with damping links (SBS-DL), are analyzed for various parameters. The study shows that seismic bifurcation (SB) helps in controlling the seismic response of tall building structures. The study further shows that SB technique is useful in improving seismic performance of conventionally-designed existing structures by way of seismic retrofitting.


2021 ◽  
pp. 136943322110105
Author(s):  
Ahmet Gullu ◽  
Ercan Yuksel ◽  
Cem Yalcin ◽  
Oral Buyukozturk

Seismic input energy per unit mass ( EI/m) imparted into a structure is a function of earthquake (duration, frequency content, amplitude etc.), soil (shear velocity, dominant period etc.) and the structural (vibrational periods etc.) characteristics. Generally, the damping properties of the structure is assumed negligible for seismic input energy. Most of the existing spectral equations derived for SDOF systems generally use a constant damping ratio of 5%. In this study, the damping effect on EI/m is investigated experimentally and numerically on SDOF systems with distinct damping ratios. Experimental investigation and numerical computations proved that seismic input energy is very sensitive to variation of damping within the vicinity of fundamental frequencies. Specifically, up to 50% increment was observed in the plateau region of the input energy spectrum, where maximum EI/m values occur, by variation of damping from 2% to 10%. Hence, a novel damping modification factor ( DMF), which could be utilized for existing energy spectra, is proposed in this paper. Validation studies of the proposed DMF are achieved through the various energy spectra found in the literature.


Buildings ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 143
Author(s):  
Kenji Fujii

The test results obtained for reinforced concrete columns by several studies have revealed that the peak displacement and cumulative hysteresis energy are important parameters for evaluating the damage of columns under horizontal bidirectional and unidirectional loading. Therefore, the seismic parameters related to the nonlinear peak displacement and cumulative hysteresis energy with regard to horizontal bidirectional seismic input should be investigated. In this study, the bidirectional seismic input to an isotropic nonlinear one-mass two-degree-of-freedom system was evaluated. First, a dimensionless parameter γ, which controls the low-cycle fatigue effect, was formulated as a function of two energy input parameters (the maximum momentary input energy and total input energy) and a nonlinear system (ductility and normalized hysteresis energy absorption during a half cycle). Then, the maximum momentary input energy and total input energy were evaluated according to the ground motion characteristics (Fourier coefficient of horizontal ground motion components) and system properties. Finally, the nonlinear peak displacement and parameter γ of the nonlinear system were evaluated on the basis of the maximum momentary input energy and total input energy. The results revealed that the nonlinear peak displacement and parameter γ can be properly evaluated using two energy parameters.


2011 ◽  
Vol 413 ◽  
pp. 46-50
Author(s):  
Yu Li ◽  
Hua Bai ◽  
Tao Wang

The energy equations of MDOF bridges are established based on the energy equilibrium theory. With considering the seismic characteristics, the FEA model of one double-column pier of passenger dedicated line is established in order to research the seismic energy response and its distribution rules when MDOF bridges entry the nonlinear state. The study results are obtained as follow: Bridge subjected to minor ground motion is depended on damping energy dissipation to consume seismic input energy. On the contrary, a large number of inelastic deformation is generated when bridge is subjected to strong ground motion. So the seismic input energy is mainly consumed by hysteretic energy dissipation. So, some meaningful references are provided for the seismic design for bridge by using energy concept.


Symmetry ◽  
2020 ◽  
Vol 12 (12) ◽  
pp. 2091
Author(s):  
Sabatino Di Benedetto ◽  
Antonella Bianca Francavilla ◽  
Massimo Latour ◽  
Giovanni Ferrante Cavallaro ◽  
Vincenzo Piluso ◽  
...  

In the last few decades, increasing efforts have been devoted to the development of beam-to-column connections able to accommodate the local ductility demand dissipating, contemporaneously, the seismic input energy. Among the typologies proposed, the so-called RBS (Reduced Beam Section) has gained wide acceptance in the construction market, leading to easy-to-construct and cost-effective solutions. As an alternative, new proposals based on the inclusion of friction devices in beam-to-column joints have recently been made. Such a practice has the merit, in case of destructive events, of exhibiting wide and stable hysteretic cycles concentrating damage in elements that undergo only minor yielding. Both RBS and friction joints have been widely studied, carrying out experimental tests on sub-assemblies investigating their cyclic rotational response. Nevertheless, the available experimental results on full-scale structures equipped with these connections are still quite limited. This is the reason why two experimental campaigns aimed at performing pseudo-dynamic testing of a full-scale two-storey steel building equipped with RBS and friction connections have been planned at the STRENGTH (STRuctural ENGineering Test Hall) Laboratory of the University of Salerno. The first experimental campaign with the structure equipped with RBSs has already been performed; the connections showed higher resistance than expected, and exhibited brittle fracture due to cyclic fatigue. The second campaign has not yet been carried out, but in this paper the blind analysis of the supposed behavior is reported. It is expected that the friction joints allow to dissipate the seismic input energy without any structural damage in the members, but only through the friction pads of the devices, which can be easily replaced at the end of a severe seismic event.


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