The Damping Effect on Constant-Ductility Seismic Demand Spectra of Inelastic Structures

2007 ◽  
Vol 348-349 ◽  
pp. 649-652
Author(s):  
Chang Hai Zhai ◽  
Mao Hua Zhang ◽  
Li Li Xie
Keyword(s):  
Damping Ratio ◽  
Linear Regression Analysis ◽  
Damage Mechanism ◽  
Seismic Demand ◽  
Displacement Ductility ◽  
Damping Effect ◽  
Inelastic Structures ◽  
Lateral Strength ◽  
Displacement Based ◽  
Ductility Capacity

The constant-ductility seismic demand spectra can provide high-sight of seismic damage mechanism of inelastic structures under the earthquake. And in the displacement-based seismic design, the constant-ductility seismic demand spectra are very useful for the preliminary design of new structures where the global displacement ductility capacity is known, which can provide the required inelastic lateral strength of new structures from the required elastic lateral strength. An in-depth investigation of damping effect on constant-ductility seismic demand spectra of inelastic structures is presented in this paper. A statistical study is performed of inelastic response computed for different damping ratio SDOF systems with different levels of lateral yielding strength required to maintain the given displacement ductility when subjected to a large number earthquake accelerations. It is concluded that the damping effect on constant-ductility seismic resistance spectra is rather complex. It depends on not only site conditions but also the structural period. Finally, results from non-linear regression analysis are presented that provide a simplified expression to be used to approximately quantify the damping effect.

scholarly journals Simplified Data-Driven Model for the Moment Curvature of T-Shaped RC Shear Walls

2019 ◽  
Vol 2019 ◽  
pp. 1-16 ◽  
Author(s):  
Bin Wang ◽  
Wenzhe Cai ◽  
Qingxuan Shi
Keyword(s):  
Cross Sections ◽  
Limit State ◽  
Shear Walls ◽  
Load Ratio ◽  
Ultimate Limit State ◽  
Limit States ◽  
Displacement Ductility ◽  
And Performance ◽  
Displacement Based ◽  
Ductility Capacity

Sectional deformation quantities, such as curvature and ductility, are of prime significance in the displacement-based seismic design and performance evaluation of structural members. However, few studies on the estimates of curvatures at different limit states have been performed on asymmetric flanged walls. In this paper, a parametric study was performed for a series of T-shaped wall cross-sections based on moment-curvature analyses. By investigating the effects of the axial load ratio, reinforcement content, material properties, and geometric parameters on curvatures at the yield and ultimate limit state, we interpret the variation in curvature with different influencing factors in detail according to the changes of the neutral axis depth. Based on the regression analyses of the numerical results of 4941 T-shaped cross-sections, simple expressions to estimate the yield curvature and ultimate curvature for asymmetric flanged walls are developed, and simplified estimates of the ductility capacity including curvature ductility and displacement ductility are further deduced. By comparing with the experimental results, we verify the accuracy of the proposed formulas. Such simple expressions will be valuable for the determination of the displacement response of asymmetric flanged reinforced concrete walls.

Response of Liquid in Cylindrical Tank with Rigid Annual Baffle Considering Damping Effect

2011 ◽  
Vol 255-260 ◽  
pp. 3687-3691 ◽  
Author(s):  
Jia Dong Wang ◽  
Ding Zhou ◽  
Wei Qing Liu
Keyword(s):  
Free Surface ◽  
Dynamic Response ◽  
Potential Function ◽  
Natural Frequencies ◽  
Damping Ratio ◽  
Cylindrical Tank ◽  
Generalized Coordinates ◽  
Damping Effect ◽  
Total Potential ◽  
Free Surface Wave

Sloshing response of liquid in a rigid cylindrical tank with a rigid annual baffle under horizontal sinusoidal loads was studied. The effect of the damping was considered in the analysis. Natural frequencies and modes of the system have been calculated by using the Sub-domain method. The total potential function under horizontal loads is assumed to be the sum of the tank potential function and the liquid perturbed function. The expression of the liquid perturbed function is obtained by introducing the generalized coordinates. Substituting potential functions into the free surface wave conditions, the dynamic response equations including the damping effect are established. The damping ratio is calculated by Maleki method. The liquid potential are obtained by solving the dynamic response equations of the system.

scholarly journals Reinforced concrete bridge pier ductility analysis for different levels of detailing

2017 ◽  
Vol 10 (5) ◽  
pp. 1042-1050
Author(s):  
R. W. SOARES ◽  
S. S. LIMA ◽  
S. H. C. SANTOS
Keyword(s):  
Reinforced Concrete ◽  
Axial Loading ◽  
Structural Element ◽  
Reinforced Concrete Column ◽  
Elastoplastic Behavior ◽  
Response Modification Factor ◽  
Concrete Confinement ◽  
Plastic Displacement ◽  
Displacement Based ◽  
Ductility Capacity

Abstract The structural design under seismic loading has been for many years based on force methods to consider the effects of energy dissipation and elastoplastic behavior. Currently, displacement-based methods are being developed to take into account elastoplastic behavior. These methods use moment-curvature relationships to determine the ductility capacity of a structural element, which is the deformation capacity of the element before its collapse. The greater the plastic displacement or rotation a structural member can achieve before it collapses, the more energy it is capable of dissipating. This plastic displacement or rotation capacity of a member is known as the member ductility, which for reinforced concrete members is directly related to efficient concrete confinement. This study investigates at which extents transverse reinforcement detailing influences reinforced concrete column ductility. For this, a bridge located in Ecuador is modeled and analyzed, and its ductility evaluated considering several cases of axial loading and concrete confinement levels. After the performed displacement-based analyses, it is verified whether the response modification factor defined by AASHTO is adequate in the analyzed case.

Dynamic Vibration Absorber for a Ropeway Carrier

1997 ◽  
Author(s):  
Hiroshi Matsuhisa ◽  
Osamu Nishihara
Keyword(s):  
Natural Frequency ◽  
Damping Ratio ◽  
Vibration Absorber ◽  
Moving Mass ◽  
Dynamic Vibration Absorber ◽  
Damping Effect ◽  
The World ◽  
Dynamic Absorber ◽  
First Time ◽  
Suspended Bridge

Abstract Ropeways such as gondola lifts have attracted increasing interest as a means of transportation in cities. However, swing of ropeway carriers is easily caused by wind, and usually a ropeway cannot operate if the wind velocity exceeds about 15m/s. The study of how to reduce the wind-induced swing of ropeway carriers has attracted many researchers. It had been said that it was impossible to reduce the vibration of pendulum type structures such as ropeway carriers by a dynamic absorber. But in 1993, Matsuhisa showed that the swing of carrier can be reduced by a dynamic absorber if it is located far above or below from the center of oscillation. Based on this finding, a dynamic absorber composed of a moving mass on an arc-shaped track was designed for practical use, and it was installed in chairlift-type carriers and gondola type carriers in snow skiing sites in Japan in 1995 for the first time in the world. It has been shown that a dynamic absorber with the weight of one tenth of the carrier can reduce the swing to half. The liquid dynamic absorber was also investigated. It has the same damping effect as the conventional solid absorber. It is easy to adjust the natural frequency and the damping ratio, and the structure is simple. Therefore, it will be applied for not only ropeway carriers but also ships and rope suspended bridge and others.

Seismic response of structural walls: recent developments

2001 ◽  
Vol 28 (6) ◽  
pp. 922-937 ◽  
Author(s):  
T Paulay
Keyword(s):  
Reinforced Concrete ◽  
Seismic Response ◽  
Seismic Design ◽  
Limit State ◽  
Lateral Force ◽  
Structural Walls ◽  
Structural Class ◽  
Response Component ◽  
Displacement Ductility ◽  
Ductility Capacity

It is postulated that for purposes of seismic design, the ductile behaviour of lateral force-resisting wall components, elements, and indeed the entire system can be satisfactorily simulated by bilinear force–displacement modeling. This enables displacement relationships between the system and its constituent components at a particular limit state to be readily established. To this end, some widely used fallacies, relevant to the transition from the elastic to the plastic domain of behaviour, are exposed. A redefinition of stiffness and yield displacement allows more realistic predictions of the important feature of seismic response, component displacements, to be made. The concepts are rational, yet very simple. Their applications are interwoven with the designer's intentions. Contrary to current design practice, whereby a specific global displacement ductility capacity is prescribed for a particular structural class, the designer can determine the acceptable displacement demand to be imposed on the system. This should protect critical components against excessive displacements. Specific intended displacement demands and capacities of systems comprising reinforced concrete cantilever and coupled walls can be estimated.Key words: ductility, displacements, reinforced concrete, seismic design, stiffness, structural walls.

Experiment Study on Reinforced Concrete Spatial Joints Subjected to Cyclic Loading

2011 ◽  
Vol 250-253 ◽  
pp. 2744-2748
Author(s):  
Chun Yang Liu ◽  
Zhen Bao Li ◽  
Hua Ma ◽  
Jian Qiang Han ◽  
Shi Cai Chen
Keyword(s):  
Reinforced Concrete ◽  
Energy Dissipation ◽  
Damage Mechanism ◽  
Experiment Study ◽  
Reinforced Concrete Frame ◽  
Displacement Ductility ◽  
Concrete Frame ◽  
Oblique Direction ◽  
Earthquake Effect ◽  
Designing Method

Experiments on reinforced concrete frame spatial joints are conducted under low level cyclic loadings.The seismic performance of the spatial joints is investigated,including failure mode,hysterisis curve, stiffness degradation,energy dissipation and displacement ductility.The experiment result shows that the column-hinge damage mechanism had happened and the bearing capactity ,energy dissipation character and displacement ductility had decreased under the oblique direction earthquake effect.The aseismic designing method should consider the oblique direction earthquake effect.

Response Characteristics of Piping System Supported by Visco-Elastic and Elasto-Plastic Dampers

1990 ◽  
Vol 112 (1) ◽  
pp. 34-38 ◽  
Author(s):  
T. Chiba ◽  
H. Kobayashi
Keyword(s):  
Energy Dissipation ◽  
Seismic Design ◽  
Damping Ratio ◽  
The Other ◽  
Piping System ◽  
Response Level ◽  
Response Characteristics ◽  
Damping Effect ◽  
Component Test ◽  
Piping Systems

Improving the reliability of the piping systems can be achieved by eliminating the mechanical snubber and by reducing the response of the piping. In the seismic design of piping system, damping is one of the important parameters to reduce the seismic response. It is reported that the energy dissipation at piping supports contributes to increasing the damping ratio of piping system. Visco-elastic damper (VED) and elasto-plastic damper (EPD) were developed as more reliable, high-damping piping supports. The dynamic characteristics of these dampers were studied by the component test and the full-scale piping model test. Damping effect of VED is independent of the piping response and VED can be modeled as a complex spring in the dynamic analysis. On the other hand, damping ratio of piping system supported by EPD increases with the piping response level. So, these dampers are helpful to increase the damping ratio and to reduce the dynamic response of piping system.

Optimal Trends in Seismic Design of Single Column Circular Reinforced Concrete Bridge Piers

1994 ◽  
Vol 10 (3) ◽  
pp. 589-614
Author(s):  
Ravindra Verma ◽  
M. J. Nigel Priestley
Keyword(s):  
Axial Load ◽  
Load Ratio ◽  
Bridge Piers ◽  
Column Height ◽  
Column Diameter ◽  
Displacement Ductility ◽  
Reinforced Concrete Bridge ◽  
Axial Load Ratio ◽  
Single Column ◽  
Ductility Capacity

An algorithm is developed to incorporate seismic capacity design philosophy in a computer program for the optimal design of single column circular reinforced concrete bridge piers for seismic loading. The program designs the circular column as a single degree of freedom system under the combined effect of axial and lateral seismic loads over a broad range of axial load ratio, column height and design displacement ductility capacity. Flexural, confinement and shear reinforcement requirements are then assessed for the entire range of parameters and cost calculations performed. For a given column height, design displacement ductility and axial load level, results indicate the existence of an optimal column diameter and ductility level. As the column diameter is reduced, cost savings are effected by reduced volume of concrete, but tend to be offset by P-Δ effects, increased longitudinal reinforcement for flexure, and increased transverse reinforcement for confinement and shear. Based on common trends, solutions are provided for the most economical range of the axial load ratio and design displacement ductility capacity for a given column height.

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