Assessment of Earthquake Performance of Structures by Hybrid Simulation

Author(s):  
Amr Elnashai ◽  
Hussam Mahmoud

With current rapid growth of cities and the move toward the development of both sustainable and resilient infrastructure systems, it is vital for the structural engineering community to continue to improve their knowledge in earthquake engineering to limit infrastructure damage and the associated social and economic impacts. Historically, the development of such knowledge has been accomplished through the deployment of analytical simulations and experimental testing. Experimental testing is considered the most accurate tool by which local behavior of components or global response of systems can be assessed, assuming the test setup is realistically configured and the experiment is effectively executed. However, issues of scale, equipment capacity, and availability of research funding continue to hinder full-scale testing of complete structures. On the other hand, analytical simulation software is limited to solving specific type of problems and in many cases fail to capture complex behaviors, failure modes, and collapse of structural systems. Hybrid simulation has emerged as a potentially accurate and efficient tool for the evaluation of the response of large and complex structures under earthquake loading. In hybrid (experiment-analysis) simulation, part of a structural system is experimentally represented while the rest of the structure is numerically modeled. Typically, the most critical component is physically represented. By combining a physical specimen and a numerical model, the system-level behavior can be better quantified than modeling the entire system purely analytically or testing only a component. This article discusses the use of hybrid simulation as an effective tool for the seismic evaluation of structures. First, a chronicled development of hybrid simulation is presented with an overview of some of the previously conducted studies. Second, an overview of a hybrid simulation environment is provided. Finally, a hybrid simulation application example on the response of steel frames with semi-rigid connections under earthquake excitations is presented. The simulations included a full-scale physical specimen for the experimental module of a connection, and a 2D finite element model for the analytical module. It is demonstrated that hybrid simulation is a powerful tool for advanced assessment when used with appropriate analytical and experimental realizations of the components and that semi-rigid frames are a viable option in earthquake engineering applications.

2021 ◽  
Author(s):  
Anthony Muff ◽  
Anders Wormsen ◽  
Torfinn Hørte ◽  
Arne Fjeldstad ◽  
Per Osen ◽  
...  

Abstract Guidance for determining a S-N based fatigue capacity (safe life design) for preloaded connectors is included in Section 5.4 of the 2019 edition of DNVGL-RP-C203 (C203-2019). This section includes guidance on the finite element model representation, finite element based fatigue analysis and determination of the connector design fatigue capacity by use of one of the following methods: Method 1 by FEA based fatigue analysis, Method 2 by FEA based fatigue analysis and experimental testing and Method 3 by full-scale connector fatigue testing. The FEA based fatigue analysis makes use of Appendix D.2 in C203-2019 (“S-N curves for high strength steel applications for subsea”). Practical use of Section 5.4 is illustrated with a case study of a fatigue tested wellhead profile connector segment test. Further developments of Section 5.4 of C203-2019 are proposed. This included acceptance criteria for use of a segment test to validate the FEA based fatigue analysis of a full-scale preloaded connector.


2011 ◽  
Vol 243-249 ◽  
pp. 4052-4055
Author(s):  
Li Dong Zhao ◽  
Bo Song

In earthquake engineering, researchers have found that many structures were not damaged after strong ground motions because of the rocking effect. In order to reveal the potential application value of the uplift effect on seismic isolation, it will be using numerical simulation software OpenSees to research the seismic response of pier considering uplift. Building the pier’s finite element model and considering the plasticity and nonlinear of the pier and soil spring, the ground motion from El Centro and TCU101 are taken as the input respectively. Through analyzing the result, it is shown that at the base of the pier the maximum bending moment is reduced by 36.93% and 46.70%, and the maximum curvature is also reduced by 78.42% and 87.12% respectively. Meanwhile, the maximum horizontal acceleration at the top of the pier is decreased 12.60% and 16.90%. The uplift effect significantly reduces the plastic deformation and plays a base-isolated role according to the results. It has also found that the earthquakes with velocity pulse effect are dangerous to the structures.


2013 ◽  
Vol 284-287 ◽  
pp. 748-753
Author(s):  
Hao Yuan Chang ◽  
Kao Hua Chang ◽  
Yi Shao Lai

The purpose of this paper is mainly to develop a method to simulate the bump height variation and probe mark profile for Eutectic (Sn63/ Pb37) bump wafer probing with continuing-touchdown probing. Certainly, the bump height variation and probe mark area on the solder bump influence the quality of the wafer probing and further impacts reliability of the packaging process after wafer probing to cause issues of cold-joint and needle damage. A three-dimensional computational model of was developed to analyze the contact phenomena between the vertical needle and the solder bump. Finite element simulation software, ANSYS, is used to analyze the loading force distributed on the vertical needle with various overdrives. In addition, the results of the bump height variation and probe mark area, which predicted by the finite element method (FEM), were verified against the on-line experimental results. Finally, the results predicted by the finite element model is consistent with experimental results and the numerical method presented in the paper can be used as a useful evaluating method to support the choice of suitable probe geometry and wafer probe testing parameters.


Author(s):  
Krishna Sai Vutukuru ◽  
Kehinde Alawode ◽  
Ali Bakhtiari ◽  
Amal Elawady ◽  
Seung Jae Lee ◽  
...  

Curtain walls are dominant cladding components of mid to high-rise buildings in modern architecture. However, the curtain wall systems have been observed highly susceptible to vibrations leading to component or system-level failure during recent extreme wind events. This paper studies the complex mechanisms of wind induced vibration (WIV) functionality at the system-and component-levels. A wind testing experiments for a full-scale single-skin façade panel was conducted at the Wall of Wind experimental facility (WOW EF) at Florida International University (FIU). Effect on the vibration of the curtain wall due to the addition of sunshade fin is also studied. The experimental protocol included testing the samples (with and without sunshade fins) at various wind speeds from 22.3 m/s to 40.1 m/s with 8.9 m/s intervals in open terrain. Effect of wind direction is also considered varying from 0 to 180 degrees with 45-degrees interval. The tests were performed on two sets of panels: (1) a polycarbonate panel (with the geometric properties maintained) to obtain dynamic wind pressure data; (2) actual glazing units that are instrumented with accelerometers and strain gauges at critical sensing locations. The experimental results indicate that the sunshade fins have a stiffening effect on the joints of the curtain walls while overall increasing the wind pressure on the panel. Dynamic amplifications on the glazing were in the order of 1.1 to 1.8 which underline the importance of studying dynamic effects on the façade systems.


2015 ◽  
Vol 1129 ◽  
pp. 242-248
Author(s):  
Hamed Makhdoumi ◽  
Seyyed Hesam Madani ◽  
Mehdi Shahraki ◽  
Mostafa Khodarahmi ◽  
Naser Nosratzehi

Abstract. After recent earthquakes in the majority of seismic areas around the world including our country Iran and considering the irretrievable casualties and economic lost due to these earthquakes, natural catastrophic mitigation committees, research and scientific centers that are responsible for providing structural and seismic codes presented the concept of performance design, study of lifelines and retrofit and rehabilitation of existing and vital structures and the majority of researches in the field of earthquake engineering and structural engineering is focused on retrofit of structures considering economic and feasibility problems. Considering the increasing use of concrete structures in Iran and their substituting for steel structures ( due to weaknesses, constructional problems and defects) and considering the internal defects and failure modes, these structures should be retrofitted against earthquakes or preparations should be provided to decrease and minimize failure modes. concrete frames that consist of beam, column and connection is a essential part of concrete structures. Internal defect of concrete frame results in failure modes such as debonding and delamination in beams, buckling and torsion in column, local crashing in connection. Considering the several benefits of FRP sheets and their increasing use during years, these composites can be used for compressive-tensile, shear, bending, torsional retrofitting as well as for ductility increasing. In this study different types of failure modes of concrete frames and internal defects of them that lead to collapse are investigated. In addition different cases of retrofitting by FRP sheets to prevent failure modes and exciting defect are presented and these cases are compared.


Author(s):  
Ali S. Shanour ◽  
Ahmed Abdelmoamen Khalil ◽  
Hany Sobhy Riad ◽  
Heba Mahmoud Bakry

This paper presents further results of experimental testing and analytical investigation on the mechanical properties of fiber composite sleeper in order to evaluate its strength and behavior. Recycled high density polyethylene, iron slag, calcium carbonate, styrene and polyester resin were used with different percentages for manufacturing the proposed composite sleepers. Adding glass fiber ropes and woven laminates as a reinforcement to enhance the flexural capacity of the proposed composite material. Negative bending at center and positive rail seat compression were performed on full scale sleeper. Two full scale sleepers were proof loaded up to 72, 82 KN under negative bending test without any generated cracks. Also, under positive rail seat compression test, first crack occurred at load ranged from 170, 195 KN and failure load happened at load 270, 250 KN. That's mean that the strength of sleeper ranged from 36.39 to 39.30 MPa. This result showed  that  the  proposed  composite  material  of  sleeper  has  sufficient  strength  to  hold mechanical connections. Nonlinear finite element analysis (NLFEA) predicted the behavior up to failure load of the proposed composite sleeper reasonably well. This confirms that the behavior and failure modes of composite sleeper can be well predicted by simplified analysis procedures. Comparison of proposed composite with commercially available composite and timber sleepers' behavior was presented. It is found that proposed composite sleeper performance is near or similar to that of timber and better than that of commercially available composite sleepers. It is concluded that the proposed composite sleeper can be effectively used for timber sleeper replacement.


Author(s):  
J Scott Thompson ◽  
Douglas D Hodson

Simulation approaches generally fall into two categories: discrete time or discrete event. For military modeling and simulation needs, the two approaches typically align with virtual simulation, which implies human interaction with the simulation program, and constructive simulation, which implies no human interaction. The Air Force Research Laboratory develops and distributes AFSIM (Advanced Framework for Simulation, Integration, and Modeling) to a user community that uses both virtual and constructive simulation. This paper documents the software design and primary algorithms that provide AFSIM’s support for both modes, which is termed a hybrid simulation.


CivilEng ◽  
2021 ◽  
Vol 2 (2) ◽  
pp. 442-458
Author(s):  
Sandip Chhetri ◽  
Rachel A. Chicchi

Experimental testing of deformed rebar anchors (DRAs) has not been performed extensively, so there is limited test data to understand their failure behavior. This study aims to expand upon these limited tests and understand the behavior of these anchors, when loaded in tension. Analytical benchmark models were created using available test data and a parametric study of deformed rebar anchors was performed. Anchor diameter, spacing, embedment, and number of anchors were varied for a total of 49 concrete breakout simulations. The different failure modes of anchors were predicted analytically, which showed that concrete breakout failure is prominent in the DRA groups. The predicted concrete breakout values were consistent with mean and 5% fractile concrete capacities determined from the ACI concrete capacity design (CCD) method. The 5% fractile factor determined empirically from the simulation results was kc = 26. This value corresponds closely with kc = 24 specified in ACI 318-19 and ACI 349-13 for cast-in place anchors. The analysis results show that the ACI CCD formula can be conservatively used to design DRAs loaded in tension by applying a kc factor no greater than 26.


2021 ◽  
pp. 136943322110073
Author(s):  
Yu Cheng ◽  
Yuanlong Yang ◽  
Binyang Li ◽  
Jiepeng Liu

To investigate the seismic behavior of joint between special-shaped concrete-filled steel tubular (CFST) column and H-section steel beam, a pseudo-static test was carried out on five specimens with scale ratio of 1:2. The investigated factors include stiffening types of steel tube (multi-cell and tensile bar) and connection types (exterior diaphragm and vertical rib). The failure modes, hysteresis curves, skeleton curves, stress distribution, and joint shear deformation of specimens were analyzed to investigate the seismic behaviors of joints. The test results showed the connections of exterior diaphragm and vertical rib have good seismic behavior and can be identified as rigid joint in the frames with bracing system according to Eurocode 3. The joint of special-shaped column with tensile bars have better seismic performance by using through vertical rib connection. Furthermore, a finite element model was established and a parametric analysis with the finite element model was conducted to investigate the influences of following parameters on the joint stiffness: width-to-thickness ratio of column steel tube, beam-to-column linear stiffness ratio, vertical rib dimensions, and axial load ratio of column. Lastly, preliminary design suggestions were proposed.


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