A new hierarchic degenerated shell element for geometrically non-linear analysis of composite laminated square and skew plates

우광성,Jin-Hwan Park,홍종현 국제구조공학회 2004 Structural Engineering and Mechanics, An Int'l Jou Vol.17 No.6

This paper extends the use of the hierarchic degenerated shell element to geometric non-linear analysis of composite laminated skew plates by the p-version of the finite element method. For thegeometric non-linear analysis, the total Lagrangian formulation is adopted with moderately largedisplacement and small strain being accounted for in the sense of von Karman hypothesis. The presentmodel is based on equivalent-single layer laminate theory with the first order shear deformation includinga shear correction factor of 5/6. The integrals of Legendre polynomials are used for shape functions withp-level varying from 1 to 10. A wide variety of linear and non-linear results obtained by the p-versionfinite element model are presented for the laminated skew plates as well as laminated square plates. Anumerical analysis is made to illustrate the influence of the geometric non-linear effect on the transversedeflections and the stresses with respect to width/depth ratio (a/h), skew angle (b), and stacking sequenceof layers. The present results are in good agreement with the results in literatures.

Seismic performance of steel plate shear walls with variable column flexural stiffness

Ivan Curkovic,Davor Skejic,Ivica Dzeba 국제구조공학회 2019 Steel and Composite Structures, An International J Vol.33 No.1

In the present study, the behavior of steel plate shear walls (SPSW) with variable column flexural stiffness is experimentally and numerically investigated. Altogether six one-bay one-story specimens, three moment resisting frames (MRFs) and three SPSWs, were designed, fabricated and tested. Column flexural stiffness of the first specimen pair (one MRF and one SPSW) corresponded to the value required by the design codes, while for the second and third pair it was reduced by 18% and 36%, respectively. The quasi-static cyclic test result indicate that SPSW with reduced column flexural stiffness have satisfactory performance up to 4% story drift ratio, allow development of the tension field over the entire infill panel, and cause negligible column "pull-in" deformation which indicates that prescribed minimal column flexural stiffness value, according to AISC 341-10, might be conservative. In addition, finite element (FE) pushover simulations using shell elements were developed. Such FE models can predict SPSW cyclic behavior reasonably well and can be used to conduct numerical parametric analyses. It should be mentioned that these FE models were not able to reproduce column "pull-in" deformation indicating the need for further development of FE simulations with cyclic load introduction which will be part of another paper.

Pose-graph optimized displacement estimation for structural displacement monitoring

이동화,명현,전해민 국제구조공학회 2014 Smart Structures and Systems, An International Jou Vol.14 No.5

A visually servoed paired structured light system (ViSP) was recently proposed as a novel estimation method of the 6-DOF (Degree-Of-Freedom) relative displacement in civil structures. In order to apply the ViSP to massive structures, multiple ViSP modules should be installed in a cascaded manner. In this configuration, the estimation errors are propagated through the ViSP modules. In order to resolve this problem, a displacement estimation error back-propagation (DEEP) method was proposed. However, the DEEP method has some disadvantages: the displacement range of each ViSP module must be constrained and displacement errors are corrected sequentially, and thus the entire estimation errors are not considered concurrently. To address this problem, a pose-graph optimized displacement estimation (PODE) method is proposed in this paper. The PODE method is based on a graph-based optimization technique that considers entire errors at the same time. Moreover, this method does not require any constraints on the movement of the ViSP modules. Simulations and experiments are conducted to validate the performance of the proposed method. The results show that the PODE method reduces the propagation errors in comparison with a previous work.

Layout optimization of wireless sensor networks for structural health monitoring

Khash-Erdene Jalsan,Rohan N. Soman,Kallirroi Flouri,Marios A. Kyriakides,Glauco Feltrin,Toula Onoufriou 국제구조공학회 2014 Smart Structures and Systems, An International Jou Vol.14 No.1

Node layout optimization of structural wireless systems is investigated as a means to prolong the network lifetime without, if possible, compromising information quality of the measurement data. The trade-off between these antagonistic objectives is studied within a multi-objective layout optimization framework. A Genetic Algorithm is adopted to obtain a set of Pareto-optimal solutions from which the end user can select the final layout. The information quality of the measurement data collected from a heterogeneous WSN is quantified from the placement quality indicators of strain and acceleration sensors. The network lifetime or equivalently the network energy consumption is estimated through WSN simulation that provides realistic results by capturing the dynamics of the wireless communication protocols. A layout optimization study of a monitoring system on the Great Belt Bridge is conducted to evaluate the proposed approach. The placement quality of strain gauges and accelerometers is obtained as a ratio of the Modal Clarity Index and Mode Shape Expansion values that are computed from a Finite Element model of the monitored bridge. To estimate the energy consumption of the WSN platform in a realistic scenario, we use a discrete-event simulator with stochastic communication models. Finally, we compare the optimization results with those obtained in a previous work where the network energy consumption is obtained via deterministic communication models.

Structural identification of Humber Bridge for performance prognosis

R. Rahbari,J. Niu,J.M.W. Brownjohn,K.Y. Koo 국제구조공학회 2015 Smart Structures and Systems, An International Jou Vol.15 No.3

Structural identification or St-Id is ‘the parametric correlation of structural responsecharacteristics predicted by a mathematical model with analogous characteristics derived from experimentalmeasurements’. This paper describes a St-Id exercise on Humber Bridge that adopted a novel two-stageapproach to first calibrate and then validate a mathematical model. This model was then used to predicteffects of wind and temperature loads on global static deformation that would be practically impossible toobserve. The first stage of the process was an ambient vibration survey in 2008 that used operational modalanalysis to estimate a set of modes classified as vertical, torsional or lateral. In the more recent second stagea finite element model (FEM) was developed with an appropriate level of refinement to provide acorresponding set of modal properties. A series of manual adjustments to modal parameters such as cabletension and bearing stiffness resulted in a FEM that produced excellent correspondence for vertical andtorsional modes, along with correspondence for the lower frequency lateral modes. In the third stage traffic,wind and temperature data along with deformation measurements from a sparse structural health monitoringsystem installed in 2011 were compared with equivalent predictions from the partially validated FEM. Thematch of static response between FEM and SHM data proved good enough for the FEM to be used topredict the un-measurable global deformed shape of the bridge due to vehicle and temperature effects but theFEM had limited capability to reproduce static effects of wind. In addition the FEM was used to showinternal forces due to a heavy vehicle to to estimate the worst-case bearing movements under extremecombinations of wind, traffic and temperature loads. The paper shows that in this case, but with limitations,such a two-stage FEM calibration/validation process can be an effective tool for performance prognosis.

Stability analysis of prestressed stayed steel columns with split-up crossarm systems

Pengcheng Li,Zhiqiang Li,Bin Jia,Hao Wang 국제구조공학회 2020 Steel and Composite Structures, An International J Vol.34 No.5

A Prestressed stayed steel column is an efficient and lightweight way with regard to enhancing the stability behaviour of a compression column. In the past, researchers primarily concentrated on investigating the behaviour of stayed steel columns with horizontal crossarms. However, this article focuses on prestressed stayed steel columns with split-up crossarm system, in which the crossarms are aslant and rotational symmetrically arranged. A mathematical formula calculating the optimal pretension that corresponds to the maximum critical buckling load was established according to geometric analysis based on the small deformation assumption. It was demonstrated that critical buckling mode of this stayed column is different from the one with horizontal crossarms. The governing imperfection direction that should be adopted in the nonlinear buckling analysis was determined in this work. In addition, the effects of crossarm inclination, stay diameter, and crossarm length on the stability behaviour were investigated. An influencing factor denotes the ratio of the load carrying capacity of the prestressed stayed steel column to the Euler load of the main column was also obtained.

Structural reliability analysis using temporal deep learning-based model and importance sampling

Truong-Thang Nguyen,Viet-Hung Dang 국제구조공학회 2022 Structural Engineering and Mechanics, An Int'l Jou Vol.84 No.3

The main idea of the framework is to seamlessly combine a reasonably accurate and fast surrogate model with the importance sampling strategy. Developing a surrogate model for predicting structures’ dynamic responses is challenging because it involves high-dimensional inputs and outputs. For this purpose, a novel surrogate model based on cutting-edge deep learning architectures specialized for capturing temporal relationships within time-series data, namely Long-Short term memory layer and Transformer layer, is designed. After being properly trained, the surrogate model could be utilized in place of the finite element method to evaluate structures’ responses without requiring any specialized software. On the other hand, the importance sampling is adopted to reduce the number of calculations required when computing the failure probability by drawing more relevant samples near critical areas. Thanks to the portability of the trained surrogate model, one can integrate the latter with the Importance sampling in a straightforward fashion, forming an efficient framework called TTIS, which represents double advantages: less number of calculations is needed, and the computational time of each calculation is significantly reduced. The proposed approach’s applicability and efficiency are demonstrated through three examples with increasing complexity, involving a 1D beam, a 2D frame, and a 3D building structure. The results show that compared to the conventional Monte Carlo simulation, the proposed method can provide highly similar reliability results with a reduction of up to four orders of magnitudes in time complexity.

Stability and vibration behavior of cellular plates with different cell arrays using a numerical approach

Chuan-Xiong Li 국제구조공학회 2023 Structural Engineering and Mechanics, An Int'l Jou Vol.85 No.6

In this paper, the shape factors of cellular meta-material plates (MMPs) having diverse cell arrays have been determined as the first attempt to finally examine their stability and vibrational frequencies. The MMPs are actually constructed from cylindrical or cubic cellular cores and two face sheets. Sandwich-like MMPs with circular and square holes in the face sheets have been selected in such a way that the effective material properties depend on the cellular architectures. For verifying the frequency results, finite element (FE) simulations are done in Abaqus software. Several graphical results have been represented to explore the effects of cellular architectures on vibrational frequencies and dynamic responses of the MMPs. Also, the deflection-frequency and stability curves in the case of forced vibrations have been plotted for diverse cell arrays.

Assessing the effect of temperature-dependent properties on the dynamic behavior of FG porous beams rested on variable elastic foundation

Abdeljalil Meksi,Mohamed Sekkal,Rabbab Bachir Bouiadjra,Samir Benyoucef,Abdelouahed Tounsi 국제구조공학회 2023 Structural Engineering and Mechanics, An Int'l Jou Vol.85 No.6

The effect of temperature dependent material properties on the free vibration of FG porous beams is investigated in the present paper. A quasi-3D shear deformation solution is used involves only three unknown function. The mechanical properties which are considered to be temperature-dependent as well as the porosity distributions are assumed to gradually change along the thickness direction according to defined law. The beam is supposed to be simply supported and lying on variable elastic foundation. The differential equation system governing the free vibration behavior of porous beams is derived based on the Hamilton principle. Navier’s method for simply supported systems is then used to determine and compute the frequencies of FG porous beam. The results of the present formulation are validated by comparing with those available literatures. Finally, the effects of several parameters such as porosity distribution and the parameters of variable elastic foundation on the free vibration behavior of temperature-dependent FG beams are presented and discussed in detail.

Confinement effect on the behavior factor of dual reinforced concrete moment-resisting systems with shear walls

Alireza Habibi,Mehdi Izadpanah,Yaser Rahmani 국제구조공학회 2023 Structural Engineering and Mechanics, An Int'l Jou Vol.85 No.6

Lateral pressure plays a significant role in the stress-strain relationship of compressed concrete. Concrete’s internal cracking resistance, ultimate strain, and axial strength are improved by confinement. This phenomenon influences the nonlinear behavior of reinforced concrete columns. Utilizing behavior factors to predict the nonlinear seismic responses of structures is prevalent in seismic codes, and this factor plays a vital role in the seismic responses of structures. This study aims to evaluate the confining action on the behavior factor of reinforced concrete moment resisting frames (RCMRFs) with shear walls (SWRCMRFs). To this end, a diverse range of mid-rise SW-RCMRFs was initially designed based on the Iranian national building code criteria. Second, the stress-strain curve of each element was modeled twice, both with and without the confinement phenomenon. Each frame was then subjected to pushover analysis. Finally, the analytical behavior factors of these frames were computed and compared to the Iranian seismic code behavior factor. The results demonstrate that confining action increased the behavior factors of SW-RCMRFs by 7-12%.