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Deterministic seismic damage analysis for concrete gravity dams: a case study of oued fodda dam

Ouzandja Djamel, Berrabah Amina Tahar

Acta Mechanica et Automatica

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2023

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Vol. 17, no. 3

347--356

EN

One of the major dangers for seismic damage of concrete dams is the propagation of cracks in dam concrete. The present study undertakes a numerical investigation of the seismic damage for Oued Fodda concrete gravity dam, located in the northwest of Algeria, considering the impacts of properties of joints along the dam-foundation rock interface and cross-stream earthquake excitation. Three-dimensional transient analyses for coupled dam-foundation rock system are carried out using Ansys software. The hydrodynamic effect of reservoir fluid is modelled using the added mass approach. The smeared crack approach is utilised to present the seismic damage of dam concrete using the Willam and Warnke failure criterion. The dam-foundation rock interface joints are presented with two ways, adhesive joints and frictional joints. The Drucker–Prager model is considered for dam concrete in nonlinear analyses. Consideration of the study results indicates that the frictional joints model can reduce the seismic response and damage hazard of the dam body to a better extent compared with the adhesive joints model. Furthermore, the application of cross-stream earthquake excitation reveals the significant effect on cracking response of the dam in the two models of joints.

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Seismic behavior and damage assessment of mid-rise cold-formed steel-framed buildings with normal and reinforced beam-column joints

Jiang Liqiang, Zhang Xingshuo, Ye Jihong, Jiang Lizhong, Zhou Lingyu

Archives of Civil and Mechanical Engineering

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2021

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Vol. 21, no. 3

675--690

EN

This paper investigated the effects of normal and reinforced beam–column joints on seismic behavior and damages of mid-rise cold-formed steel (CFS) framed buildings, where the reinforced beam–column joint is strengthened by a pair of steel blocks and a gusset plate. Shaking table tests were conducted on a 5-story CFS frame building with normal beam-column joint (CFSM-NJ) and a 5-story CFS frame building with same configurations but with reinforced beam–column joint (CFSM-RJ). Formulae fitted from four damage models were used to assess the seismic damage indexes of these test buildings, and the assessed results were validated by the damage indexes observed from tests. The results show the following: (1) the CFSM-NJ failed due to plastic hinges formed at the column bases and large separate deformation at the beam-column joints; however, the weaken-story failure mode was appeared on the CFSM-RJ; (2) the peak inter-story displacement of the building was reduced about 10–30% due to the reinforced beam-column joints; (3) the Park-Ang model is more appropriate for seismic damage assessment of column bases, but all the damage models overestimates the seismic damages of CFS beams. Finally, the authors comment on the difference between the assessed seismic damage indexes and the observed results, and the maximum damage indexes obtained from the simplified formulae are recommended as the preliminary assessed damages for mid-rise CFS buildings.

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Seismic damage behaviour of aeolian sand reinforced concrete columns with I-shaped structural steel

Wang Y. H., Wang H. Y., Wang Y. P., Zhao M., Qi J., Huo G. Z., Liu P. Q.

Archives of Civil Engineering

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2020

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Vol. 66, nr 4

633--650

EN

To promote the application of aeolian sand resources for steel-concrete composite structures, an aeolian sand reinforced concrete column with I-shaped structural steel is proposed in this study. Four specimens are designed and manufactured with different replacement rates of aeolian sand. The seismic behaviour and damage evolution process of the specimens are studied by low-cycle repeated loading tests. Based on the test results, the mechanical characteristics, failure modes, hysteresis curves, skeleton curves, energy dissipation capacity, displacement ductility, and stiffness degradation of the specimens with different replacement rates of aeolian sand are analysed. In addition, the effects of the design parameters on the seismic behaviour of the specimens are also studied. The results show that the indexes of the seismic behaviour can be significantly improved by adding steel. Moreover, a revised damage model is proposed, to better reflect the evolution law of seismic damage of aeolian sand reinforced concrete columns with steel. The proposed model can provide an important reference for seismic damage assessment of the columns.

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Collapse of the single layered cylinder shell with model experimental study

Nie Gui-bo, Zhang Chen-xiao, Zhi Xu-dong, Dai Jun-wu

Archives of Civil and Mechanical Engineering

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2019

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Vol. 19, no. 3

883--897

EN

With the rapid development of the large-span space structure, it has been widely used in the public buildings such as gymnasiums, exhibition hall, airplane terminal, etc. in China recently. The large-span latticed shell buildings are usually the landmark buildings in a city, so its collapse will cause serious economic and personal loss, which will affect national security and social stability. The shaking table test was conducted on the single layered cylinder shell model in this paper, and the dynamic amplification effects of the lower support frame and the dynamic responses of the whole model were obtained under different seismic motion inputs. The seismic performance of the single layered cylinder shell was evaluated under different ground motion inputs and input principal directions, and the collapse mode was obtained. The results show that the input principal direction has great effect on the dynamic characteristics of the model, and the dynamic amplification effect of the lower support frame increases with the magnitude increase of the ground motion inputs. There is no obvious impact effect and the dynamic strain responses behave elastic during the collapse process, and the whole shell collapse because of local instability. It concludes that the single layered cylinder shell has the risk of progressive collapse under the seismic motions, so the collapse resistance of single layered cylinder shell should be enhanced or it should be optimum designed to prevent the progressive collapse. This experimental study will provide references to the seismic design and engineering practices.