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1

Centrifugal shaking experiments and FEM analytical investigation on masonry block reinforcement of small earth dams

Wang Bohan, Mohri Yoshiyuki, Hidekazu Tagashira, Izumi Akira, Tanaka Tadatsugu

Archives of Civil Engineering

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2024

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Vol. 70, nr 1

443--458

EN

In this research, a series of centrifuge model tests and dynamic response analyses were conducted to elucidate the impact of a composite structure comprised of a reinforced earth-pressure-resistant technique, using both masonry blocks and the reinforced earth method, which was installed at the slope toe end of an aged reservoir. The purpose of the study was to evaluate the seismic response of the embankment. The experimental tests included shaking table tests that were performed on an unreinforced embankment as well as a masonry block reinforced embankment, both in a water storage condition. The dynamic behavior of the embankment, as well as the propagation of slip failure, were compared and verified. Through the use of elasto-plastic dynamic response analysis, using the finite element method, the location of the slip surface, the settlement of the embankment and the dynamic response characteristics, as obtained experimentally, were examined to clarify the effects of the counter measure structure. The results indicate that the implementation of masonry blocks and the reinforcement installed behind them greatly improve the stability of the slope of the embankment, suppress the shear failure of the upper part of the embankment, and effectively prevent overall deformation of the embankment.

2

Influence of vertical ground motion on seismic responses of triple friction pendulum interlayer isolation structures

Fang Zhao, Yan Ping

Archives of Civil Engineering

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2021

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Vol. 67, nr 3

581--597

EN

In order to investigate the influence of vertical ground motion on seismic responses of story-isolation structures mounted on triple friction pendulum (TFP) bearings, the finite element model of a six-story building with various types of interlayer isolation TFP bearings under far field or near fault ground motions is established and analysed. A discrepancy rate function of peak interlayer shear, acceleration and displacement results is adopted to discuss the influence of the vertical seismic motions on isolation structural responses. Furthermore, the isolation form, the isolation period and the friction coefficient of bearings are changed to study their effect on the vertical seismic component’s influence. The results show that the influence of the vertical seismic component is considerable on the isolation layer especially under near-fault ground motions, so it should not be overlooked during the structural design; The change of isolation forms will greatly affect the influence of the vertical seismic component especially in the isolation layer and isolation systems with isolation devices set on higher stories or with less isolation layers will have less vertical seismic effect on story acceleration; The increase of the isolation period will globally result in the decrease of the influence of vertical seismic components, though in some cases it shows some sort of fluctuation before the final decrease; The increase of the friction coefficient will lead to the global decrease in the influence of the vertical seismic component in single-layer isolation structures, while it does not obviously affect those in the multi-layer isolation systems.

3

Seismic evaluation of deficient reinforced concrete weak beam-column joint frames

Rizwan Muhammad, Ahmad Naveed, Khan Akhtar Naeem, Fahad Muhammad

Archives of Civil Engineering

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2020

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Vol. 66, nr 4

429--451

EN

The use of old building design codes and improper execution of recent seismic design practices have caused large amount of substandard and vulnerable reinforced concrete RC building stock majority of which are built with weak beam-column joint connections defect (i.e. joint panel having no transverse reinforcement and built in low strength concrete). In order to understand the seismic response and damage behaviour of recent special moment resisting frame SMRF structures with the defect of weak beam-column joints, shake table tests have been performed on two 1:3 reduced scaled, two story RC frame models. The representative reference code design and weak beam-column joint frame models were subjected to uni-directional dynamic excitations of increasing intensities using the natural record of 1994 Northridge Earthquake. The input scaled excitations were applied from 5% to 130% of the maximum input peak ground acceleration record, to deformed the test models from elastic to inelastic stage and then to fully plastic incipient collapse stage. The weak beam-column frame experienced column flexure cracking, longitudinal bar-slip in beam members and observed with cover concrete spalling and severe damageability of the joint panels upon subjected to multiple dynamic excitations. The deficient frame was only able to resist 40% of the maximum acceleration input as compared to the code design frame which was able to resist about 130%. The seismic performance of considered RC frames was evaluated in terms of seismic response parameters (seismic response modification, overstrength and displacement ductility factors), for critical comparison.

4

Seismic evaluation of mixed steel and RC columns in hybrid high-rise buildings

Kontoni D. P. N., Farghaly A. A.

Archives of Civil Engineering

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2019

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Vol. 65, nr 2

3--17

EN

The growth in high-rise building construction has increased the need for hybrid reinforced concrete and steel structural systems. Columns in buildings are the most important elements because of their seismic resistance. Reinforced concrete (RC) columns and steel columns were used herein to form hybrid structural systems combining their distinct advantages. Eleven 3D building models subjected to earthquake excitation with reinforced concrete beams and slabs of 12 floors in height and with different distributions of mixed columns were analyzed by the SAP2000 software in order to investigate the most suitable distributions of a combination of reinforced concrete and steel columns. Top displacements and accelerations, base normal forces, base shear forces, and base bending moments were computed to evaluate the selected hybrid structural systems. The findings are helpful in evaluating the efficiency of the examined hybrid high-rise buildings in resisting earthquakes.

5

Investigating the performance of isolation systems in improving the seismic behavior of urban bridges. A case study on the Hesarak Bridge

Edalati Ali Akbar, Tahghighi Hossein

Archives of Civil Engineering

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2019

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Vol. 65, nr 4

155--175

EN

This paper investigates the influence of isolation systems on the seismic behavior of urban reinforce concrete bridge. The performance of the Hesarak Bridge constructed in Karaj city, Iran with two isolation systems; i.e. the existing elastomeric rubber bearing (ERB) and a proposed lead rubber bearing (LRB) is discussed. The numerical model was implemented in the well-known FEM software CSIBridge. The isolated bridge has been analyzed using nonlinear time history analysis method with seven pairs of earthquake records and the results are compared for the two isolation systems. The LRB isolators are shown to have superior seismic performance in comparison with the existing ERB systems based on the response evaluation including force on the isolator, pier base shear, deck acceleration, bending moment, pier displacement, and energy dissipation.