Cyclic behavior and hysteretic model of steel ring restrainers

In this paper we have analyzed the influence of the strain hardening behavior of High Damping Rubber Bearings (HDRBs) adopted for a base isolation system of a Reinforced Concrete (RC) isolated structure. For the modeling of the rubber isolators we have adopted an evolution of the Bouc-Wen’s hysteretic model taking into account the incremental hardening effect which appears when the shear strain of the HDRB exceeds the limit value around 100% usually adopted in design practice. The incremental hardening effect is sometimes neglected in the design but it is an important aspect because it ensures a seismic protection of the base isolated structure also in presence of exceptional seismic events for intensity or frequency content. In this paper we have highlighted the significant influence of this phenomenon in the seismic response of the isolated structure by reporting the cyclic behavior of a HDRB respectively neglecting and considering this aspect.

Download Full-text

Cyclic performance of frames with prestressed steel–concrete composite beams

Canadian Journal of Civil Engineering ◽

10.1139/l08-040 ◽

2008 ◽

Vol 35 (10) ◽

pp. 1064-1075

Author(s):

Weichen Xue ◽

Kun Li ◽

Renguang Zheng ◽

Liang Li

Keyword(s):

Composite Beam ◽

Composite Beams ◽

Cyclic Behavior ◽

Small Contribution ◽

Hysteretic Model ◽

Cyclic Performance ◽

High Deformation ◽

Failure Patterns ◽

Composite Frames ◽

The Common

This paper presents a study of the cyclic performance of moment-resisting frames with prestressed steel–concrete composite beams subjected to cyclic displacement reversals. The failure patterns, failure mechanism, hysteretic model, ductility, energy dissipation capacity, stiffness degradation, and deformation-restoring capacity of two composite frames are discussed. Larger slip could be observed along the beam span of the frame with the common composite beam in comparison with the prestressed composite beam. A four-linear hysteretic model with descending branches and two pinching pivot points is proposed for the two composite frames. Tests show that both the test frames failed in a beam side-sway mechanism within the plane of the frame, and the frame with the prestressed composite beam develops relatively high deformation restoring capacity. The applied prestressing in the composite beam has a small contribution to cyclic behavior of the composite frame. Studies also show that more energy is dissipated by the frame with the prestressed composite beam than that with the common composite beam.

Download Full-text

New Metallic Damper with Multiphase Behavior for Seismic Protection of Structures

Metals ◽

10.3390/met11020183 ◽

2021 ◽

Vol 11 (2) ◽

pp. 183

Author(s):

Amadeo Benavent-Climent ◽

David Escolano-Margarit ◽

Julio Arcos-Espada ◽

Hermes Ponce-Parra

Keyword(s):

Energy Dissipation ◽

Large Deformations ◽

Cyclic Behavior ◽

Displacement Curve ◽

Hysteretic Model ◽

Reinforced Concrete Structure ◽

Shake Table Tests ◽

Energy Dissipation Capacity ◽

Multiphase Behavior ◽

Metallic Damper

This paper proposes a new metallic damper based on the plastic deformation of mild steel. It is intended to function as an energy dissipation device in structures subjected to severe or extreme earthquakes. The damper possesses a gap mechanism that prevents high-cycle fatigue damage under wind loads. Furthermore, subjected to large deformations, the damper presents a reserve of strength and energy dissipation capacity that can be mobilized in the event of extreme ground motions. An extensive experimental investigation was conducted, including static cyclic tests of the damper isolated from the structure, and dynamic shake-table tests of the dampers installed in a reinforced concrete structure. Four phases are distinguished in the response. Based on the results of the tests, a hysteretic model for predicting the force-displacement curve of the damper under arbitrary cyclic loadings is presented. The model accurately captures the increment of stiffness and strength under very large deformations. The ultimate energy dissipation capacity of the damper is found to differ depending on the phase in which it fails, and new equations are proposed for its prediction. It is concluded that the damper has a stable hysteretic response, and that the cyclic behavior, the ultimate energy dissipation capacity and failure are highly predictable with a relatively simple numerical model.

Download Full-text

Evaluation of the MPA Procedure for Estimating Seismic Demands: RC-SMRF Buildings

Earthquake Spectra ◽

10.1193/1.2945295 ◽

2008 ◽

Vol 24 (4) ◽

pp. 827-845 ◽

Cited By ~ 20

Author(s):

Hugo Bobadilla ◽

Anil K. Chopra

Keyword(s):

Ground Motions ◽

Pushover Analysis ◽

Cyclic Behavior ◽

Hysteretic Model ◽

Practical Application ◽

Seismic Demands ◽

Modal Pushover Analysis ◽

Moment Resisting Frame ◽

Moment Resisting ◽

Special Moment Resisting Frame

The modal pushover analysis (MPA) procedure is extended for analysis of reinforced concrete special moment resisting frame (RC-SMRF) buildings, after demonstrating that the theory, assumptions, and approximations underlying this procedure are valid for such systems. The principal extension of the procedure is in the hysteretic model for modal SDF systems, chosen as the peak-oriented model to represent the global monotonic and cyclic behavior of such buildings, characterized by deterioration of stiffness and strength under cyclic deformation. The median seismic demands for 4-, 8-, 12-, and 20-story RC-SMRF buildings—designed to comply with current codes—due to an ensemble of 78 ground motions scaled to four intensity levels were computed by MPA and nonlinear RHA, and compared. It is demonstrated that, even for the most intense ground motions that deform the buildings far into the inelastic range, the MPA procedure demonstrates an adequate degree of accuracy that should make it useful for practical application in estimating seismic demands for RC-SMRF buildings. In contrast the FEMA-356 force distributions are inadequate in estimating seismic demands for the 8-, 12-, and 20-story buildings at all excitation intensities, from the weakest that causes response essentially within the linearly elastic range, to the strongest that drives the buildings far into the inelastic range.

Download Full-text