Establishing optimal gap size for precast beam bridges with a buffer-gap-elastomeric bearings system

Farag, Mostafa M.; Mehanny, S. S. F.; Bakhoum, Mourad M.

doi:10.12989/eas.2015.9.1.195

Cited by 13 publications

(6 citation statements)

References 11 publications

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“…Dashpots are installed at the base, to simulate the half‐space below the 20 m of the soil. The damping coefficient is calculated as follows:

C_{b} goodbreak= ρ V_{S} A

where ρ = 2.1 t/m 3 the clay material density, V s the shear‐wave velocity corresponding to half‐space, and A the effective area of each dashpot. In addition, ‘node‐to‐node’ kinematic constraints are applied along the lateral boundaries of the model (forcing two nodes to have identical displacements).…”

Section: Numerical Test Casementioning

confidence: 99%

“…1 Essentially, horizontal isolation is achieved by decoupling the superstructure from its base during shaking and hence, preventing load transfer to the structural members. 2 To this end, a variety of seismic isolation devices have been developed, mainly for applications in bridges and structures of high importance, comprising from simple elastomeric bearings (with and without lead core 3 ) to more sophisticated roller bearings and viscous dampers. However, the solution of the base isolation is not panacea and cannot be implemented in every structural application; accelerations are controlled and maintained within reasonable limits, but the demand for large base displacements renders this technology inadequate for a number of cases.…”

Section: Introduction and Scopementioning

confidence: 99%

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A negative stiffness dynamic base absorber for seismic retrofitting of residential buildings

Mantakas

Kapasakalis

Alvertos

et al. 2022

Structural Contr & Hlth

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In this study, a negative stiffness-based passive vibration absorber is developed and implemented as a seismic retrofitting measure for typical reinforced concrete (RC) residential buildings. The device, namely, the extended KDamper for retrofitting (EKD-R), is introduced at the base of the structure, between the foundation level and the first story of the building. The design of the EKD-R device and the selection of its properties are undertaken by incorporating a harmony search (HS) algorithm that provides optimized parameters for the mechanism, following constraints and limitations imposed by the examined structural system. Nonlinearities due to the plastic behavior of the structural members and soil-structure interaction (SSI) effects are modeled and taken into consideration during the process. Subsequently, a realistic case study of a benchmark three-story RC building is examined, and the performance of the EKD-R system is assessed. The building superstructure is designed according to Eurocodes. The structure-foundation system, along with the EKD-R, is explicitly modeled using finite elements (FE) that may realistically capture structural nonlinearities and SSI effects. The HS algorithm is employed, and optimized EKD-R components are obtained and implemented in the benchmark structure. Finally, a series of recorded real ground motions are selected, and nonlinear time-history dynamic analyses are conducted aiming to assess the behavior of the controlled system. Results indicate the beneficial role of the novel dynamic absorber, hence rendering the concept a compelling seismic retrofitting technology.

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“…Dashpots are installed at the base, to simulate the half‐space below the 20 m of the soil. The damping coefficient is calculated as follows:

C_{b} goodbreak= ρ V_{S} A

Section: Numerical Test Casementioning

confidence: 99%

Section: Introduction and Scopementioning

confidence: 99%

A negative stiffness dynamic base absorber for seismic retrofitting of residential buildings

Mantakas

Kapasakalis

Alvertos

et al. 2022

Structural Contr & Hlth

View full text Add to dashboard Cite

show abstract

“…However, these structures still suffer from permanent drifts and increased top storey accelerations, which can result in loss of serviceability, material and equipment damage, and potential degradation of the structural members [1]. To this end, seismic isolation has been one of the main approaches to decouple the superstructure from the foundation level and thus, protect the structure from the loads transferred during earthquake excitation [2][3][4][5]. The main drawback of such approach is the required large base displacement and complex implementation, rendering the system expensive and inadequate for retrofitting of existing structures.…”

Section: Introductionmentioning

confidence: 99%

Performance Evaluation of Negative Stiffness-Based Vibration Control Devices for Seismic Protection of Building Structures

Kapasakalis,

Mantakas,

Kalderon

et al. 2023

Proceedings of the 8th International Conference on Computational Methods in Structural Dynamics and Earthquake Engineering (COM

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In this research work, the KDamper concept is extended and applied to multiple floors of an existing midrise storey benchmark building. Inspired by the concept of MTMDs, multiple EKDs (d-EKDs) are installed and distributed along the height of the aforementioned structure, aiming to seismically protect it. The design and spatial allocation of the EKDs is based on a Harmony Search (HS) algorithm that provides optimal parameters of the device based on constraints and limitations imposed by the structure and the installed mechanisms. A number of Eurocode 8 compatible accelerograms are generated and introduced as input to the optimization process of the EKDs installed in the benchmark structure. Based on the numerical results obtained, the d-EKD concept, outperforms the d-TMD in reducing the structural dynamic responses, introducing one order of magnitude smaller added oscillating masses.

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“…Isolation systems in the bases of the structures essentially provide horizontal isolation from the effects of earthquake shaking by decoupling the superstructure from the base‐foundation during earthquakes. In this context, a variety of isolation devices including elastomeric bearings (with and without lead core), frictional/sliding bearings, and roller bearings have been developed.…”

Section: Introductionmentioning

confidence: 99%

Performance assessment of the KDamper as a seismic Absorption Base

Kapasakalis

Antoniadis

Sapountzakis

2020

Struct Control Health Monit

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Summary The KDamper is a novel passive vibration absorption concept based essentially on the optimal combination of appropriate stiffness elements, one of which has a negative value. In this paper, the implementation of the KDamper as a seismic Absorption Base (KDAB) is considered. The performance of the KDAB is assessed in three characteristic test cases, namely, a rigid body and two flexible buildings with fundamental periods of 0.5 and 1.0 s, respectively. In all three cases, the structures are excited by real and artificial accelerograms. The performance of the KDAB is compared not only with the original structure but also with the cases of conventional and highly damped base isolation systems, as well as with the case of a tuned mass damper inerter. Alternative options for the selection of the KDamper nominal frequency are considered, leading to two cases. In the first one, the nominal KDamper frequency is selected equal to the low frequency of a conventional base isolation system, resulting in a drastic improvement of the overall structural performance (i.e., superstructure accelerations and base drifts). In the second one, the KDAB is implemented with a much higher nominal frequency, leading to a drastic reduction of the relative base displacement, in the order of few centimeters, combined with acceptable structural performance. As a consequence, the KDamper can be implemented as a supplement of a conventional base isolation system or, alternatively, as a “stiff absorption base,” overcoming the disadvantages of seismic isolation approaches, leading towards new seismic protection technologies.

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Establishing optimal gap size for precast beam bridges with a buffer-gap-elastomeric bearings system

Cited by 13 publications

References 11 publications

A negative stiffness dynamic base absorber for seismic retrofitting of residential buildings

A negative stiffness dynamic base absorber for seismic retrofitting of residential buildings

Performance Evaluation of Negative Stiffness-Based Vibration Control Devices for Seismic Protection of Building Structures

Performance assessment of the KDamper as a seismic Absorption Base

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