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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

Real-time hybrid test of a LNG storage tank with a variable curvature friction pendulum system

Lin Shu-chao, Wang Jingxuan, Gao Shan, Zhao Hong-tie

Archives of Civil and Mechanical Engineering

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2021

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Vol. 21, no. 3

44--62

EN

To accurately reproduce the seismic response of the liquefied natural gas (LNG) storage tank equipped with the variable curvature friction pendulum system (VCFPS), a real-time hybrid (RTH) experiment, also known as a real-time substructure experiment, is conducted on it in this study. A typical LNG storage tank with a capacity of 160,000 m3 is employed as the numerical substructure simulated using the MATLAB/Simulink, while the variable curvature friction pendulum bearing (VCFPB) is utilized as the experimental substructure tested using the compression-shear equipment. Thereafter, the validity and feasibility of the RTH experiment are verified using the SAP2000 results. Finally, the working performance of the VCFPB is evaluated scientifically, comprehensively, reasonably, and efficiently. The results show that the VCFPB is very effective in avoiding the resonance phenomenon. It can be seen from the displacement of isolation layer that the VCFPB meets the design requirement. The maximum relative deviations between the RTH test results and the SAP2000 results are 3.45% for the displacement of isolation layer, 4.27% for the base shear, and 1.49% for the liquid sloshing height, respectively. The RTH test is stable and reliable and the predicted results are highly accurate and effective. The RTH test method proves to be accurate in the prediction of the seismic response of the LNG storage tank equipped with the VCFPBs.

4

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.

5

Seismic response investigation and analytical model of light polymer material-filled CFS shear walls

Wang Wanqian, Wang Jingfeng, Guo Lei, Shen Qihan

Archives of Civil and Mechanical Engineering

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2020

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Vol. 20, no. 2

423--436

EN

The light polymer material (LPM), prepared with suitable mix proportion and physical method, is a type of low-carbon and environmental-friendly material. Recently, the LPM is developed as structural material for cold-formed steel (CFS) structures to cover the shortages of traditional CFS shear wall. In this paper, material properties of gypsum-based and cement-based LPM including compressive strength, elastic modulus and thermal property were explored by tests. Experimental results demonstrate that LPM exhibits excellent thermal insulation, and the thermal insulation and compressive strength of LPM satisfy the demand of bearing capacity and thermal insulation property of shear walls. To explore the effect of LPM on seismic response and failure modes of CFS shear walls, three specimens are manufactured and tested under cyclic loading. The existence of LPM in CFS shear wall would restrain the failure of wall studs to some extent. Due to the restriction effect of LPM on wall studs and self-drilling screws and the bond-slip performance between LPM and studs, the shear walls exhibit better seismic behavior than traditional CFS shear walls. At last, a modified equivalent bracing model is employed to predict the lateral stiffness of LPM-filled CFS shear walls considering the effect of filling materials, rib lath, and sheathing. The lateral stiffness obtained by the proposed method is compared to the experimental results in this paper and other researches, and the proposed model is proved to supply a conservative result which is safe to be adopted in the design and application of the LPM-filled CFS shear wall.

6

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.

7

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.

8

Stiffness effects of structural elements on the seismic response of RC high-rise buildings

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

Archives of Civil Engineering

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2018

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Vol. 64, nr 1

3--20

EN

The stiffness of structural elements (columns, beams, and slabs) significantly contributes to the overall stiffness of reinforced concrete (RC) high-rise buildings (H.R.B.s) subjected to earthquake. In order to investigate what percentage each type of element contributes to the overall performance of an H.R.B. under seismic load, the stiffness of each type of element is reduced by 10% to 90%. A time history analysis by SAP2000 was performed on thirteen 3D models of 12-story RC buildings in order to illustrate the contribution of column stiffness and column cross sections (rectangular or square), building floor plans (square or rectangular), beam stiffness and slab stiffness, on building resistance to an earthquake. The stiffness of the columns contributed more than the beams and slabs to the earthquake resistance of H.R.B.s. Rectangular cross-section columns must be properly oriented in order for H.R.B.s and slender buildings to attain the maximum resistance against earthquakes.

PL

Aby zbadać, jaki procent każdego rodzaju elementów (słupów, belek i płyt) wpływa na ogólną sztywność i wydajność wieżowców (H.R.B.) pod obciążeniem sejsmicznym, sztywność każdego elementu jest zmniejszana o 10% do 90%. Analiza historyczna przeprowadzona przez SAP2000 obejmowała trzynaście modeli 3D 12-piętrowych wieżowców w celu zobrazowania wpływu sztywności i przekrojów słupa (prostokątnego lub kwadratowego), planu pięter budynku (kwadratowego lub prostokątnego), sztywności belki oraz sztywności płyty, na odporność budynku na trzęsienie ziemi. Sztywność słupa miała większy wpływ niż sztywność belki i płyty na odporność wieżowca na trzęsienie ziemi.