The Experts below are selected from a list of 222 Experts worldwide ranked by ideXlab platform
H Hofmeyer - One of the best experts on this subject based on the ideXlab platform.
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racking shear resistance of steel Frames with corner connected precast concrete infill panels
Steel and Composite Structures, 2015Co-Authors: J C D Hoenderkamp, H H Snijder, H HofmeyerAbstract:When precast concrete infill panels are connected to steel Frames at discrete locations, interaction at the structural interface is neither complete nor absent. The contribution of precast concrete infill panels to the lateral stiffness and strength of steel Frames can be significant depending on the quality, quantity and location of the discrete interface connections. This paper presents preliminary experimental and finite element results of an investigation into the composite behaviour of a square steel Frame with a precast concrete infill panel subject to lateral loading. The panel is connected at the corners to the ends of the top and bottom beams. The Frame-to-Panel-Connection, FPC4 between steel beam and concrete panel consists of two parts. A T-section with five achor bars welded to the top of the flange is cast in at the panel corner at a forty five degree angle. The triangularly shaped web of the T-section is reinforced against local buckling with a stiffener plate. The second part consists of a triangular gusset plate which is welded to the beam flange. Two bolts acting in shear connect the gusset plate to the web of the T-section. This way the connection can act in tension or compression. Experimental pull-out tests on individual connections allowed their load deflection characteristics to be established. A full scale experiment was performed on a one-storey one-bay 3 by 3 m Infilled Frame structure which was horizontally loaded at the top. With the characteristics of the Frame-to-panel connections obtained from the experiments on individual connections, finite element analyses were performed on the Infilled Frame structures taking geometric and material non-linear behaviour of the structural components into account. The finite element model yields reasonably accurate results. This allows the model to be used for further parametric studies.
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lateral behavior of steel Frames with discretely connected precast concrete infill panels
2005Co-Authors: C S Kleinman, H H Snijder, H Hofmeyer, P A TeeuwenAbstract:As an alternative to the conventional structures for tall buildings, a hybrid lateral load resisting structure has been designed at Eindhoven University of Technology. It consists of discretely connected precast concrete panels with window openings in steel Frames, and is a new application in Infilled Frames. Besides the structural advantages of hybrid construction, this structure offers an alternative construction method, improving the constructability of tall buildings. This will result in more economical and high quality buildings. The Infilled Frame is a type of structure that has proven to be effective and efficient in bracing low-rise and medium-rise buildings to resist in-plane lateral loads. It acts by composite action between the infill and its surrounding Frame. Structural interaction between the two components produces a composite structure with a complicated behavior due to the fact that the Frame and the infill mutually affect each other. Since the early fifties extensive research has been done into the composite behavior of Infilled Frames with masonry and cast-in-place concrete infills without openings. However, the application of discretely connected concrete panels with openings as bracing elements in steel Frame structures has not been performed yet and represents a new area of research in Infilled Frames. The main objective of this investigation is to develop practical universally applicable design models for Infilled steel Frames with discretely connected precast concrete panels, allowing for an accurate prediction of the strength, stiffness and deformation capacity of this type of structure. In order to develop these design models, the structure has been subjected to experimental, numerical and analytical investigation. First, full-scale tests on single-storey, single-bay Infilled Frame structures were carried out. Objectives of this experimental study were to observe the general behavior of the Infilled Frame in terms of stiffness, strength and failure modes. In addition, experiments were performed on components of the discrete panel-to-Frame connection. Subsequently, finite element models were developed and validated by simulating the experiments. For this purpose, finite element analyses taking non-linear material and structural behavior into account were performed. It has been shown that the finite element model developed for the overall Infilled Frame behavior can be used to predict the lateral load versus deflection relationship and the ultimate lateral load with good accuracy. Accordingly, the validated finite element model has been used to carry out a parameter study to investigate various configurations of the Infilled Frame. Four parameters have been studied with respect to their influence on the structural response. These parameters are the Frame member dimensions, the rotational stiffness of the Frame joints, the Infilled Frame aspect ratio and the panel opening geometry. From the simulated load-deformation curves, structural characteristics have been derived. These have served as a verification for the developed analytical models for the prediction of the lateral stiffness, the ultimate lateral load and deformation capacity of the structure under consideration. The analytical models are based on the concept of the equivalent diagonal strut, considering the structure as an equivalent braced Frame system with a compression diagonal replacing the infill. Finally, a practical method for designing steel Frames with discretely connected precast concrete infill panels has been proposed. The aim of this method is to get a good prediction of the internal forces and the lateral deflection in the preliminary phase of the design, without the use of advanced computer simulations. The design method provides a useful guideline that a design engineer can follow, in order to design building structures consisting of steel Frames with discretely connected precast concrete infill panels, resulting in a ductile structure, possessing both adequate strength and stiffness.
Tianyou Guo - One of the best experts on this subject based on the ideXlab platform.
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in plane behaviour of a reinforcement concrete Frame with a dry stack masonry panel
Materials, 2016Co-Authors: Kun Lin, Yuri Z Totoev, Hongjun Liu, Tianyou GuoAbstract:In order to improve the energy dissipation of the masonry Infilled Frame structure while decreasing the stiffening and strengthening effects of the infill panels, a new dry stacked panel (DSP) semi-interlocking masonry (SIM) infill panel has been developed. In this paper, the material properties of DSP and a traditional unreinforced masonry (URM) panel have been evaluated experimentally. A series of cyclic tests were performed to investigate the cyclic behaviour of the reinforcement concrete (RC) Frame with different infill panels. The failure modes, damage evolution, hysteretic behaviour, stiffness degradation and energy dissipation were compared and analysed. We concluded that DSP is capable of significantly improving the seismic energy dissipation due to its hysteretic behaviour when the Frame is in elastic stage without increasing the stiffness of the Frame. Therefore, DSP or SIM panels can be considered as frictional dampers. Based on the experimental results, the influence of DSP was examined. Using the parallel model, the hysteretic loops of DSP subjected to different load cases were achieved. The typical full hysteretic loop for DSP could be divided into three distinct stages of behaviour: packing stage, constant friction stage and equivalent strut stage. The connection between the panel and the Frame had a great effect on the transferring of different mechanical stages. The constant friction stage was verified to provide substantial energy dissipation and benefits to the ductility of the structure, which, therefore, is suggested to be prolonged in reality.
Arslan Cherifati - One of the best experts on this subject based on the ideXlab platform.
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influence of masonry infill panels on the vibration and stiffness characteristics of r c Frame buildings
Earthquake Engineering & Structural Dynamics, 1999Co-Authors: Amar A Chaker, Arslan CherifatiAbstract:Vibration measurements were performed on two adjacent, three-storey reinforced concrete Frame buildings with hollow clay brick infill panels. The first building was a bare Frame, and the second one was a similar Frame Infilled with brick panels. The fundamental period for the Infilled Frame building was much smaller than that of the bare Frame building. Using shear beam lumped mass models and the vibration data, the actual lateral stiffness of both buildings was identified. The lateral stiffness of the Infilled Frame building was found to be seven times that of the bare Frame building. Four numerical models of the Infilled Frame building were constructed. The Frame and floors were represented using an experimentally validated model, and the infill panels by one of three commonly used equivalent diagonal truss' models or by plane stress finite elements. Only the plane stress finite element model produced a reasonable agreement with the experimental results.
Wooyoung Jung - One of the best experts on this subject based on the ideXlab platform.
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energy dissipating polymer matrix composite infill wall system for seismic retrofitting
Journal of Structural Engineering-asce, 2003Co-Authors: Amjad J Aref, Wooyoung JungAbstract:Polymer matrix composite ~PMC!-infill walls hold great promise for energy dissipation when used in retrofitting applications where seismic activity is a consideration. This paper presents the analysis, design, and testing of PMC-infill walls developed for seismic retrofitting applications. The PMC-infill wall system consists of two fiber-reinforced polymer laminates with an infill of vinyl sheet foam. At the interface between the laminates, viscoelastic honeycomb is used to dissipate energy and improve the damping characteristics of the structure. As part of this research, analytical and experimental studies were performed to explore the effectiveness of this seismic retrofitting strategy and to examine the behavior of the PMC-infill wall system when subjected to monotonic and cyclic loading. A steel Frame retrofitted with a PMC-infill wall was monitored to assess the resultant enhancements to its seismic-energy resistance capacity. In testing the PMC-infill wall system in this research, a large-scale steel Frame was used to avoid the typical uncertainties associated with scaling the dimensions. The optimal design for the stacking sequence of a PMC-infill wall panel was determined based on the performance and material cost using the finite-element analysis. Finally, the observed behavior of the PMC-Infilled Frame was assessed on the bases of stiffness, strength, modes of failure, and energy dissipation output. The experimental and analytical studies demonstrate that the intro- duction of a PMC-infill wall panel in a semirigidly connected steel Frame produces significant enhancements to stiffness, strength, and energy dissipation.
Andreas Stavridis - One of the best experts on this subject based on the ideXlab platform.
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nonlinear finite element model updating of an Infilled Frame based on identified time varying modal parameters during an earthquake
Journal of Sound and Vibration, 2014Co-Authors: Eliyar Asgarieh, Babak Moaveni, Andreas StavridisAbstract:Abstract A model updating methodology is proposed for calibration of nonlinear finite element (FE) models simulating the behavior of real-world complex civil structures subjected to seismic excitations. In the proposed methodology, parameters of hysteretic material models assigned to elements (or substructures) of a nonlinear FE model are updated by minimizing an objective function. The objective function used in this study is the misfit between the experimentally identified time-varying modal parameters of the structure and those of the FE model at selected time instances along the response time history. The time-varying modal parameters are estimated using the deterministic–stochastic subspace identification method which is an input–output system identification approach. The performance of the proposed updating method is evaluated through numerical and experimental applications on a large-scale three-story reinforced concrete Frame with masonry infills. The test structure was subjected to seismic base excitations of increasing amplitude at a large outdoor shake-table. A nonlinear FE model of the test structure has been calibrated to match the time-varying modal parameters of the test structure identified from measured data during a seismic base excitation. The accuracy of the proposed nonlinear FE model updating procedure is quantified in numerical and experimental applications using different error metrics. The calibrated models predict the exact simulated response very accurately in the numerical application, while the updated models match the measured response reasonably well in the experimental application.
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nonlinear finite element model updating of a large scale Infilled Frame structures based on instantaneous modal parameters
31st IMAC A Conference on Structural Dynamics 2013, 2013Co-Authors: Eliyar Asgarieh, Babak Moaveni, Andreas StavridisAbstract:While linear finite element (FE) model updating has been successfully applied for predicting structural damage as loss of effective stiffness, nonlinear FE model updating can provide improved and more accurate damage identification (i.e., a more comprehensive measure of damage) and can additionally be used as a tool for damage prognosis. The current study is focused on characterizing the nonlinear material behavior in a FE model of a three-story Infilled Frame using the identified instantaneous natural frequencies and mode shapes. The 2/3-scale, 3-story, 2-bay reinforced concrete Frame with masonry infills was subjected to large amplitude earthquake base excitations on a shake table. The deterministic stochastic subspace identification method is used for estimating the instantaneous (during short-time windows) modal parameters of the structure based on the nonlinear response of structure during a seismic base excitation. Parameters of a priori selected hysteretic models (Bouc-Wen) at different finite elements of the structural model are calibrated to minimize the misfit between the identified modal parameters and those from the FE model. The accuracy of the calibrated FE model is assessed through the comparison of the predicted response and natural frequencies obtained from the model with those of the specimen.
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nonlinear structural identification of a three story Infilled Frame using instantaneous modal parameters
2012Co-Authors: Eliyar Asgarieh, Babak Moaveni, Andreas StavridisAbstract:Even though modal analysis theory is not applicable to nonlinear dynamic structural systems, such systems can be characterized by their time-varying amplitude-dependent instantaneous modal parameters. In this study, the nonlinear behavior of a large-scale test structure is characterized based on its time-varying instantaneous modal parameters identified during an earthquake. The test structure is a 2/3-scale, three-story, two bay, masonry-Infilled reinforced concrete Frame, tested on the University of California, San Diego (UCSD) outdoor shake table. Deterministic stochastic subspace identification (DSI) method is used for estimation of instantaneous modal parameters of the structure based on sliding time windows of input-output data during a seismic base excitation. These identified time-variant modal parameters are used to estimate the effective stiffness of different components of the test structure corresponding to its tangent stiffness matrix through a linear finite element (FE) model updating strategy. Variation of the identified stiffness as a function of maximum displacement can be used to characterize the hysteretic behavior at element/substructure level.
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system identification of a three story Infilled rc Frame tested on the ucsd nees shake table
Scopus, 2011Co-Authors: Babak Moaveni, Andreas Stavridis, Benson P ShingAbstract:A 2/3-scale, three-story, two-bay, Infilled RC Frame was dynamically tested on a shake-table. The test objectives were to assess the seismic performance of existing, non-ductile, Infilled RC Frames and provide data for the evaluation of newly developed analytical methods predicting the behavior of such structures. The shake-table tests were designed to induce damage on the structure progressively through scaled earthquake records of increasing intensity. Between the earthquake records, the response of the Frame to low-amplitude ambient vibration and white-noise base excitation tests was measured. At these low levels of excitations, the structure can be considered as a quasi-linear system with parameters depending on the damage state. The deterministicstochastic subspace identification method based on system input and output signals has been used to estimate the modal parameters of the test structure at its various damage states. The identification is conducted considering the white-noise base excitation and the resulting structural response measured by accelerometers. The study has quantified the decrease of natural frequencies and the increase of structural damping at progressive damage states. The identified modal parameters have been used for damage identification of the Infilled Frame in a companion paper.