Open System For Earthquake Engineering Simulation Research Articles

Numerical predictions of observed failure modes on non-ductile reinforced concrete frames

This manuscript reports on numerical predictions of documented failure modes on two dynamic experimental datasets involving nonductile reinforced concrete (RC) frames. The numerical models are created using available methodologies in the Open System for Earthquake Engineering Simulation (OpenSEES). Failure mode limits are applied to the components' responses to identify flexural, shear on beam-column joints, pullout, and bond-slip failure modes observed in the experimental studies. The experimental datasets available are used in the assessment of the numerical predictions. The assessment of predictions indicated that the numerical models reproduce well the failure modes, global and local responses of the RC frames on the experimental datasets. The results demonstrate that (i) failure mechanisms involving pullout and bond-slip could dominate the collapse mechanisms on nonductile frames, and (ii) the underestimation of bond deformations on numerical analysis could overestimate section stiffness. The validated modeling methods are used to study the effects of the ground motion characteristics on the predicted failure modes. The results of numerical analysis of a 3-story frame under two sets of near-field and far-field ground motions highlighted the need to include modeling tools that capture bond-slip, pullout, and shear on joints. The formation of bond-slip under near-field motions is highly correlated to the motion's peak ground velocity levels, this correlation is less evident for far-field motions. Peak drift trends resemble the peak ground velocity trends for the near-field and far-field sets.

Experimental and numerical study on seismic performance of deficient interior RC joints retrofitted with prestressed high-strength steel strips

This paper presents the results of an experimental and numerical study on strapping method for retrofitting deficient interior RC beam-column joints, which do not meet the requirements of current seismic design codes due to some deficiencies including low strength of concrete, inadequate transverse reinforcements, and low construction quality. In order to explore the seismic behavior of the retrofitted RC joints, six interior joint specimens, including two deficient RC joints with inadequate transverse rebar, three RC joints retrofitted with prestressed high-strength steel strips and one RC joint retrofitted with adhesively-bonded steel and prestressed high-strength steel strips, were designed and tested under cyclic loading. The main variables included the retrofit methods, axial compression ratio and volume of steel strips. The test results indicated that the prestressed steel strips worked together well with the deficient RC joints, and the retrofitted specimens exhibited better seismic behavior than the deficient control specimens, especially in deformability and energy dissipation. On the basis of the experimental study, the corresponding numerical model was established using the Open System for Earthquake Engineering Simulation (OpenSEES) and then verified to be valid. Finally, the modified softened strut and tie model was proposed in this paper to calculate the shear capacities of the specimens, and the calculated results agreed well with the test results.

Validation of Finite Element Model by Smart Aggregate-Based Stress Monitoring.

Concrete compressive strength is an important parameter of material properties for assessing seismic performance of reinforced concrete (RC) structures, which has a certain level of uncertainty due to its inherent variability. In this paper, the method of concrete strength validation of finite element model using smart aggregate (SA)-based stress monitoring is proposed. The FE model was established using Open System for Earthquake Engineering Simulation (OpenSEES) platform. The concrete strengths obtained from the material test, peak stress of SA, and estimated concrete strength based on SA stress were employed in FE models. The lateral displacement monitored by Liner variable differential transformer and vertical axial load monitored by load cell in the experiment are applied in the model. By comparing the global response (i.e., lateral reaction force and hysteretic loop), local response (i.e., concrete stress, rebar strain, and cross-section moment) and corresponding root-mean-square error obtained from experiment and numerical analysis, the capabilities of validation of FE model using SA-based stress monitoring method were demonstrated.

High-performance computer-aided optimization of viscous dampers for improving the seismic performance of a tall building

Using fluid viscous dampers (FVDs) has been demonstrated to be an effective method to improve seismic performance of new and existing buildings. In engineering applications, designs of these dampers mainly rely on trial and error, which is repetitive and labor intensive. To improve on this tedious manual process, it is beneficial to explore more formal and automated approaches that rely on recent advances in software applications for nonlinear dynamic analysis, performance-based evaluation, workflow management and the computational power of high-performance, parallel processing computers. The optimization design procedure follows the framework of Performance Based Earthquake Engineering (PBEE) and uses an automatic tool that incorporates an optimization engine and structural analysis software: Open System for Earthquake Engineering Simulation (OpenSEES). An existing 35-story steel moment frame is selected as a case-study building for verification of this procedure. The goal of the retrofit design of FVDs is to improve the building's seismic behavior to avoid collapse under a Level 2, basic safety earthquake event (BSE-2E). An objective function of building's total loss under a BSE-2E event is used and its optimal damper patterns will be proposed. The efficiency of the optimization procedure will be demonstrated and compared with the manual procedure.

High-Performance Computer-Aided Optimization of Viscous Dampers for Improving the Seismic Performance of a Tall Steel Building

Using fluid viscous dampers (FVDs) has been demonstrated to be an effective method to improve seismic performance of new and existing buildings. In engineering applications, designs of these dampers mainly rely on trial and error, which could be repetitive and labor intensive. To improve this tedious manual process, it is beneficial to explore more formal and automated approaches that rely on recent advances in software applications for nonlinear dynamic analysis, performance-based evaluation, and workflow management and the computational power of high-performance, parallel processing computers. The optimization design procedure follows the framework of Performance Based Earthquake Engineering (PBEE) and uses an automatic tool that incorporates an optimization engine and structural analysis software: Open System for Earthquake Engineering Simulation (OpenSEES). An existing 35-story steel moment frame is selected as a case-study building for verification of this procedure. The goal of the retrofit design of FVDs is to improve the building’s seismic behavior that focuses on avoiding collapse under a basic-safety, level-2 earthquake (BSE-2E). The objective of the optimization procedure is to reduce the building’s total loss under a BSE-2E event and optimal damper patterns will be proposed. The efficiency of the optimization procedure will be demonstrated and compared with a manual refinement procedure.

Seismic performance of fiber-reinforced concrete interior beam-column joints

Fiber-reinforced concrete (FRC), as an advanced alternative to normal concrete, has been increasingly used to construct beam-column joints which is one of the most congested parts of reinforcements in reinforced concrete (RC) structures because of its potentially beneficial properties. The present work aims to investigate the seismic performance of FRC beam-column joints experimentally and numerically. A total of eight beam-column joints, including both FRC beam-column joints and RC beam-column joint, were conducted to explore its seismically important features under quasi-static reversed cyclic load, mainly including the failure modes, hysteretic response, energy dissipation, stiffness degradation. It was found that the application of FRC can effectively improve the seismic performance of beam-column joints because it leads to higher load-carrying capacity and a greater deformation capability prior to the formation of the major diagonal cracks in the joint core zone. A numerical study, using the Open System for Earthquake Engineering Simulation (OpenSEES), was also conducted to study the seismic performance of beam-column joints deeply after its applicability and accuracy being validated with test data. The prediction from the proposed numerical model shows a good agreement with test data. Furthermore, a parametric study was generated to address and evaluate the effects on the seismic performance of FRC beam-column joints from different parameters, including the axial load ratios, transverse reinforcement ratios and FRC compressive strength. The results indicate that the increment of axial load ratios and FRC compressive strength can enhance the load-carrying capacity.

Improving Anti-seismic and Collapse-Resistance Ability of Building Structure Based on Building Information Model

Building information model plays an irreplaceable role in strengthening anti-seismic ability of building structure, it can form automatically by applying Finite Element Analysis Software and Open System for Earthquake Engineering Simulation. Conducted effective structure analysis model according to international basic-class industrial file and select targeted information data. The angle and prospectiveness of model analysis can be developed continuously so that anti- seismic and collapse-resistance ability of building structure can be strengthened constantly. Relevant sub-model transfers various information data in order to improve accuracy of model data analysis. Finite Element Analysis Software and Open System for Earthquake Engineering Simulation positively promote constructing information model; at the same time, they actively strengthen digital construction of model, reasonability and systematicness of information data analysis. Wish this study can provide useful data and theory support for further exploring work. Hope building information model can be applied more in enhancing anti-seismic and collapse-resistance ability of building structure.