Forward directivity near-fault and far-fault ground motion effects on the behavior of reinforced concrete wall tall buildings with one and more plastic hinges

Struct. Design Tall Spec. Build.

Kheyroddin

Kafi

2016

Self Cite

In this study, different energy components in the tall reinforced concrete core-wall buildings with numerous plastic hinges over the height are investigated using nonlinear time history analysis. The effect of near-fault and far-fault earthquakes is compared. The idea of one-plastic, two-plastic, three-plastic and whole-plastic hinge approaches along the core wall is examined. The input energy, inelastic, damping, kinetic and elastic strain energy during the earthquakes are studied. The results show that a large energy quantity transfers to the structure at the arrival time of the near-fault motion pulse. Inelastic energy distribution over the height shows a considerable amount of inelastic energy dissipation occurring at the base and above the mid-height of the walls.The 20-story, 30-story and 40-story core-wall structures with fixed bases and with a typical story height of 3.5 m are considered here in this research. For the design purpose, a three-dimensional linear 802 H. BEIRAGHI, A. KHEYRODDIN AND M. A. KAFI

Section: Discussionmentioning

confidence: 99%

“…Figure shows the general view of the models. More information on designed buildings could be found elsewhere (Beiraghi et al, ).…”

Section: Rc Core‐wall Designmentioning

confidence: 99%

Energy dissipation of tall core-wall structures with multi-plastic hinges subjected to forward directivity near-fault and far-fault earthquakes

Struct. Design Tall Spec. Build.

Kheyroddin

Kafi

2016

Self Cite

“…Commonly, in the RSA procedure, modal responses are reduced by an identical R factor for all modes. Several researchers have demonstrated that the formation of plastic hinges at the base of the cantilever walls essentially reduces response of the first vibration mode, while higher vibration modes are not reduced to the same degree as the first mode (Beiraghi et al ., ). Therefore, the conventional RSA procedure is not an appropriate approach for designing of cantilever walls with plasticity at the base (Priestley et al ., ).…”

Section: Introductionmentioning

confidence: 97%

Seismic assessment of RC core-wall building capable of three plastic hinges with outrigger

Struct Design Tall Spec Build

Siahpolo

2016

Self Cite

In a core-wall structure with buckling restrained braces (BRB) outrigger, locations of the plastic hinges are influenced by the outrigger action. Therefore, the designer should consider the issue and use suitable details in the plastic hinge area. The essential questions that arise here are the plastic hinge location and the design moment demand used for design of this kind of structure. In this paper, responses of the core-wall buildings with BRB outrigger designed by using the traditional response spectrum analysis procedure are assessed by implementing the nonlinear time history analysis. The result demonstrates that the plasticity can extend over anywhere within the core-walls specially, at the base and above or below the outrigger levels. Formation of three plastic hinges in the core-wall is recognized suitable for the system. To control the plasticity extension in the core-wall, it is recommended that a new modal combination method be applied to calculate the moment strength of the three plastic hinges over the height. A capacity design concept is used to design other regions of the core-wall where the plasticity does not extend to. The proposed procedure improves behavior of the system by restricting the plasticity extension to the predefined plastic hinge regions. levels in the first case. Therefore, placement of the outrigger at 0.5H is not recommended according to the displacement demand. CAPACITY DESIGN APPROACHThe philosophy of capacity design in structural seismic engineering ensures that during an earthquake, the structure responds in a favorable ductile manner. This is achieved by pre-selecting an appropriate plastic mechanism and then providing special detailing to the plastic hinge regions. Providing enough ductility in these regions leads to energy dissipation under severe earthquakes (Park and Paulay, 1975;Paulay and Priestley, 1992). Capacity design approach can keep the large portion of the core-walls elastic and facilitate the detailing of the reinforcement there. The ease of detailing and reduction in Figure 11. Average of the (a) curvature ductility, (b) moment, (c) shear, (d) inter-story drift ratio and (e) lateral displacement envelop, in 40-story core-wall.

“…These ground motions, called pulse-like ground motions, have been identi ed as the cause of severe demands in structures, which can exceed the expected demands typically resulting from Response Spectrum Analysis (RSA) procedure [26][27][28][29][30]. Many studies have demonstrated that buildings located in an NF zone undergo highly inelastic responses caused by velocity pulses in the fault normal component of some seismic ground motions [31][32][33].…”

Section: Introductionmentioning

confidence: 99%

Forward directivity near-fault and far-fault ground motion effects on the responses of tall reinforced concrete walls with buckling-restrained brace outriggers

2017

Scientia Iranica

Self Cite

Abstract. In this study, the responses of reinforced concrete core-wall structures connected to the outside columns by Buckling-Restrained Brace (BRB) outriggers in tall buildings were investigated. The buildings were subjected to forward directivity Near-Fault (NF) and ordinary Far-Fault (FF) ground motions. According to the current codes for the DBE level, the response spectrum analysis procedure was applied to analyze and design the structures. The nonlinear ber element approach was used to simulate the reinforced concrete core-walls. Nonlinear time history analysis was implemented using 14 NF as well as 14 FF records at MCE level. In the core-wall, the results showed that the mean moment demand envelope and the mean shear demand envelope obtained from the NF records were approximately similar to the corresponding demand envelopes from FF records. The reason had to do with extending plasticity all over the RC core-wall, which was subjected to both sets of records. The overall responses of the reinforced concrete core-wall with BRB outrigger system were in acceptable range both for NF and FF earthquakes. In this study, the largest curvature ductility demand in the reinforced concrete core-wall took place at levels just above the outriggers.