• Structural Monitoring and Maintenance
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• v.10 no.1
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• pp.87-105
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• 2023

Seismic regulations have been updated from time to time to accommodate an increase in seismic hazards. Comparison of seismic fragility of the existing bridges in Indonesia from different historical periods since the era before 1990 will be the basis for seismic assessment of the bridge stock in Indonesia, most of which are located in earthquake-prone areas, especially those built many years ago with outdated regulations. In this study, seismic fragility curves were developed using incremental non-linear time history analysis and more holistically according to the actual strength of concrete and steel material in Indonesia to determine the uncertainty factor of structural capacity, βc. From the research that has been carried out, based on the current seismic load in SNI 2833:2016/Seismic Map 2017 (7% probability of exceedance in 75 years), the performance level of the bridge in the era before SNI 2833:2016 was Operational-Life Safety whereas the performance level of the bridge designed with SNI 2833:2016 was Elastic - Operational. The potential for more severe damage occurs in greater earthquake intensity. Collapse condition occurs at As = F_PGA x PGA value of bridge Era I = 0.93 g; Era II = 1.03 g; Era III = 1.22 g; Era IV = 1.54 g. Furthermore, the fragility analysis was also developed with geometric variations in the same bridge class to see the effect of these variations on the fragility, which is the basis for making bridge risk maps in Indonesia.

• Earthquakes and Structures
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• v.22 no.3
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• pp.231-243
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• 2022

Beam-column joints (BCJs) are recognized among the most crucial zones in reinforced concrete structures, as they are the critical elements subjected to a complex state of forces during a severe earthquake. Under such conditions, BCJs exhibit behaviors with impacts that extend to the whole structure and significantly influence its ductility and capability of dissipating energy. The focus of this paper is to investigate the effect of undamaged transverse beam (secondary beams) on the ductility of concrete BCJs reinforced with conventional steel and shape memory alloys bars using pushover analysis at tip of beam under different axial load levels at the column using a nonlinear finite element model in ABAQUS environment. A numerical model of a BCJ was constructed and the analysis outcomes were verified by comparing them to those obtained from previous experiments found in the literature. The comparison evidenced the capability of the calibrated model to predict the load capacity response of the joint. Results proved the ability of undamaged secondary beams to provide a noticeable improvement to the ductility of reinforced concrete joints, with a very negligible loss in load capacity. However, the effect of secondary beams can become less significant if the beams are damaged due to seismic effects. In addition, the axial load was found to significantly enhance the performance of BCJs, where the increase in axial load magnified the capacity of the joint. However, higher values of axial load resulted in greater initial stiffness of the BCJ.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.41 no.1
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• pp.21-28
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• 2021

The main purpose of this study is to assess the safety of the fixed anchorages subjected to the seismic motion for an operating facilities in the actual power plant. Thus, the experimental study was conducted to investigate the load response in the event of an actual seismic to the anchorages of a nonstructural components. Since there are economic and spatial constraints to study nonstructural components that actually have various forms, alternative test specimens of steel frames with mass were built and the shaking table test was carried out. In order to evaluate the dynamic characteristics and seismic performance, the natural frequency of the target structure was identified through the shaking table test and then the load response characteristics of the anchorage were evaluated by generating an artificial seismic effect like actual seismic. Finally, the structural stiffness was reinforced by fixing the steel frame to the test specimen using bolts, thereby reducing the load transmitted to the anchorage. It will be carried out on the reliability verification of the experiments and areas that have not been carried out due to the site conditions through the analytical approach in the future.

• Earthquakes and Structures
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• v.12 no.6
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• pp.629-641
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• 2017

Foundation plays a significant role in safe and efficient turbo machinery operation. Turbo machineries generate harmonic load on the foundation due to their high speed rotating motion which causes vibration in the machinery, foundation and soil beneath the foundation. The problems caused by vibration get multiplied if the soil is poor. An improperly designed machine foundation increases the vibration and reduces machinery health leading to frequent maintenance. Hence it is very important to study the soil structure interaction and effect of machine vibration on the foundation during turbo machinery operation in the design stage itself. The present work studies the effect of harmonic load due to machine operation along with earthquake loading on the frame foundation for poor soil conditions. Various alternative foundations like rafts, barrette, batter pile and combinations of barrettes with batter pile are analyzed to study the improvements in the vibration patterns. Detailed computational analysis was carried out in SAP 2000 software; the numerical model was analyzed and compared with the shaking table experiment results. The numerical results are found to be closely matching with the experimental data which confirms the accuracy of the numerical model predictions. Both shake table and SAP 2000 results reveal that combination of barrette and batter piles with raft are best suitable for poor soil conditions because it reduces the displacement at top deck, bending moment and horizontal displacement of pile and thereby making the foundation more stable under seismic loading.

• Earthquakes and Structures
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• v.12 no.1
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• pp.23-34
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• 2017

Composite steel plate deep beam (CDB) is proposed as a lateral resisting member, which is constructed by steel plate and reinforced concrete (RC) panel, and it is connected with building frame through high-strength bolts. To investigate the seismic performance of the CDB, tests of two 1/3 scaled specimens with different length-to-height ratio were carried out under cyclic loads. The failure modes, load-carrying capacity, hysteretic behavior, ductility and energy dissipation were obtained and analyzed. In addition, the nonlinear finite element (FE) models of the specimens were established and verified by the test results. Besides, parametric analyses were performed to study the effect of length-to-height ratio, height-to-thickness ratio, material type and arrangement of RC panel. The experimental and numerical results showed that: the CDBs lost their load-carrying capacity because of the large out-of plane deformation and yield of the tension field formed on the steel plate. By increasing the length-to-height ratio of steel plate, the load-carrying capacity, elastic stiffness, ductility and energy dissipation capacity of the specimens were significantly enhanced. The ultimate loading capacity increased with increasing the length-to-height ratio of steel plate and yield strength of steel plate; and such capacity increased with decreasing of height-to-thickness ratio of steel plate and gap. Finally, a unified formula is proposed to calculate their ultimate loading capacity, and fitting formula on such indexes are provided for designation of the CDB.

• Advances in Computational Design
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• v.9 no.1
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• pp.1-23
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• 2024

Present paper deals with the cost effective design of reinforced concrete building frame employing unified particle swarm optimization (UPSO). A building frame with G+8 stories have been adopted to demonstrate the effectiveness of the present algorithm. Effect of seismic loads and wind load have been considered as per Indian Standard (IS) 1893 (Part-I) and IS 875 (Part-III) respectively. Analysis of the frame has been carried out in STAAD Pro software.The design loads for all the beams and columns obtained from STAAD Pro have been given as input of the optimization algorithm. Next, cost optimization of all beams and columns have been carried out in MATLAB environment using UPSO, considering the safety and serviceability criteria mentioned in IS 456. Cost of formwork, concrete and reinforcement have been considered to calculate the total cost. Reinforcement of beams and columns has been calculated with consideration for curtailment and feasibility of laying the reinforcement bars during actual construction. The numerical analysis ensures the accuracy of the developed algorithm in providing the cost optimized design of RC building frame considering safety, serviceability and constructional feasibilities. Further, Monte Carlo simulations performed on the numerical results, proved the consistency and robustness of the developed algorithm. Thus, the present algorithm is capable of giving a cost effective design of RC building frame, which can be adopted directly in construction site without making any changes.

• Journal of the Earthquake Engineering Society of Korea
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• v.20 no.4
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• pp.269-276
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• 2016

Seismic performance evaluation of existing building usually needs much time and man power, especially in case of nonlinear analysis. Many data interaction steps for model transfer are needed and engineers should spend much time with simple works like data entry. Those time-consuming steps could be reduced by applying computerized and automated modules. In this study, computational platform for seismic performance evaluation was made with several computerized modules. StrAuto and floor load transfer module offers a path that can transfer most linear model data to nonlinear analysis model so that engineers can avoid a lot of repetitive work for input information for the nonlinear analysis model. And the new nonlinear property generator also helps to get the nonlinear data easily by importing data from structural design program. To evaluate the effect of developed modules on each stages, seismic performance evaluation of example building was carried out and the lead time was used for the quantitative evaluation.

• Geomechanics and Engineering
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• v.29 no.6
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• pp.599-614
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• 2022

In this study, the reliability analysis of internal and external stabilities of Reinforced Soil Walls (RSWs) under static and seismic loads are investigated so that it can help the geotechnical engineers to perform the design more realistically. The effect of various variables such as angle of internal soil friction, soil specific gravity, tensile strength of the reinforcements, base friction, surcharge load and finally horizontal earthquake acceleration are examined assuming the variables uncertainties. Also, the correlation coefficient impact between variables, sensitivity analysis, mean change, coefficient of variation and type of probability distribution function were evaluated. In this research, external stability (sliding, overturning and bearing capacity) and internal stability (tensile rupture and pull out) in both static and seismic conditions were investigated. Results of this study indicated sliding as the predominant failure mode in the external stability and reinforcing rupture in the internal stability. First-Order Reliability Method (FORM) are applied to estimate the reliability index (or failure probability) and results are validated using the Monte Carlo Simulation (MCS) method. The results showed among all variables, the internal friction angle and horizontal earthquake acceleration have dominant impact on the both reinforced soil wall internal and external stabilities limit states. Also, the type of probability distribution function affects the reliability index significantly and coefficient of variation of internal friction angle has the greatest influence in the static and seismic limits states compared to the other variables.

• Earthquakes and Structures
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• v.25 no.4
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• pp.283-296
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• 2023

This paper presents experimental and numerical studies of seismic performance on reinforced concrete (RC) wide beam (WB) joints. Two RC-WB joint specimens and one conventional RC joint specimen were fabricated using the reinforcing details of longitudinal reinforcing bars in a beam as a variable, and quasi-static cyclic loading tests were performed. The results were used to compare and analyze the load-drift ratio relationship, failure mode, and seismic performance of the specimens quantitatively. In addition, a finite element (FE) analysis of the RC-WB joint was conducted, and the rationality of the FE model was validated by comparing it with the test results. Based on the FE model, a parametric study was conducted, where the ratio of longitudinal reinforcing bars placed on the outer and inner parts of the joint (𝜌_ex/𝜌_in) was a key variable. The results showed that, in the RC-WB joint, an increase of 𝜌_ex/𝜌_in leads to more severe damage to concrete, which reduces the seismic performance of the RC-WB joints.

• Structural Engineering and Mechanics
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• v.92 no.1
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• pp.25-52
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• 2024

In the current paper, the various responses of concrete rectangular liquid storage containers under seismic load, each isolated by a lead-rubber bearing subjected to bi-directional earthquake forces are investigated. A parametric study is conducted to investigate the effects of isolation period, yield strength of the isolator and the effects of soil-foundation interaction for non-isolated and base-isolated tanks located on different soil types. In most cases, the value of base shear, base moment, wall displacement and hydrodynamic pressure is reduced by the effect of the isolators whose effective frequency is within the appropriate range. The sloshing displacement is amplified due to seismic isolation of the tanks for both tall and shallow tank configurations. Also, it is found that the seismic isolation technique is more efficient for the more flexible tank. Studying various soil types indicates that, unlike the responses of non-isolated tanks which change drastically for different soil types, the responses of base-isolated structures are less affected. Finally, it is observed that the variation in structural responses is not only related to the superstructure configuration and bearings properties but also depends on the earthquake specifications.