Structural Analysis Software Package Research Articles

Mechanical model of the over-stroke displacement behaviour for double concave surface slider anti-seismic devices

For double concave curved surface slider (DCCSS) isolators with a flat rim and lacking restrainers, such as those most commonly used in Europe, the rigid slider can exceed the geometrical capability of the housing plate during earthquakes stronger than those produced in simulations. During this over-stroke displacement, DCCSSs preserve the ability to support superstructure gravity loads and the capacity to dissipate energy. There are currently no applicable hysteresis rules or available algebraic solutions that can be used to predict over-stroke behaviour for response-history analysis. This study presents an algebraic solution to extend basic theories for estimating the actual limit displacement of DCCSS devices with over-stroke capacity. DCCSS behaviour in the over-stroke sliding regime was modelled with a focus on geometrical compatibility and kinematics. The proposed analytical formulation was calibrated on the basis of experimental controlled-displacement tests performed on single DCCSS devices. A case study of a six-storey reinforced concrete frame isolated building was modelled using a combination of non-linear elements that are currently available in several structural analysis software packages and able to correctly model over-stroke displacement behaviour for non-linear time history analyses. The DCCSS model was augmented with a friction model capable of accounting for torsional effects, axial load, and velocity variabilities. Comparison with non-linear dynamic analysis outcomes shows that the forces and displacements in the over-stroke sliding regime are predictable and therefore useful for the designer.

Modeling methods and constitutive laws for nonlinear analysis of steel moment-resisting frames

This article presents several methods to model beams, columns, and panel zones of steel moment-resisting frames that incorporate force interaction, deterioration, and plasticity distribution. The methods combine the element classes and material types that exist in almost all structural analysis software packages. After introducing the element assemblies and the related constitutive laws, their accuracy is verified against several component experiments and a shake table test. Supplementary finite element analyses are included for panel zones to clarify their key behavioral parameters. The results showed the efficiency of the Fiber section And Spring Element (FASE) modeling method in capturing the actual response of bare beams and the columns resisting moderate-constant axial forces. In the case of composite beams, it adequately considered their asymmetric behavior when resisting positive and negative moments. The Fiber section And Truss Element (FATE) modeling method, developed for columns with high-variational axial forces, captured the axial force-bending moment interaction and the column axial shortening reported in past experiments. The proposed model for the panel zone accounted for all the shear and bending moment interaction, web shortening, and participation of flanges affecting its stiffness and strength. Ultimately, the integrity and accuracy of the proposed modeling methods in nonlinear time history analyses were verified by simulating a shake table test.

AN RBF BASED HIGH-DIMENSIONAL MODEL REDUCTION APPROACH IN BUILDING OPTIMIZATION

Building optimization has gained importance with the recent push to create the most economical and efficient buildings possible. As the effects of optimization are a function of the building size, it is crucial to understand and further develop optimization techniques for large-scale building structures. Practical structural optimization of buildings requires the use of a structural analysis software package and an iterative optimization procedure. As a result, finite element (FE) software shall be linked with an optimization solver. It is an expensive process which requires extensive computer coding. Alternative methods are available, including metamodeling methods, which are used to create simple and approximate functions based on complex FE simulations. In this study, the approximate functions are generated using a high-dimensional model representation (HDMR) framework. The HDMR framework is a model reduction approach and is found to be very accurate for different functions. The component functions of HDMR are expressed using augmented radial basis functions (RBFs). To further improve the numerical efficiency of the metamodels and reduce the total required number of structural analyses, a few different HDMR sampling approaches are investigated, including one static approach and two iterative strategies. An existing nonlinear programming (NLP) solver is employed in the design process. To illustrate the proposed approach, a three-dimensional building structure is selected as a numerical example. The numerical optimization is conducted to reduce the torsional response of the building. The proposed optimization method works very well and the results from different HDMR techniques are compared.

Soil–Structure Interaction and Structural Design of Raft-Foundation and Reinforced Concrete Superstructure

Raft foundations can be analyzed using the conventional, Winkler, and continuum methods. In the conventional method, it is assumed that the raft is rigid and settles uniformly. In the Winkler method, commonly employed in structural analysis software packages, soil is represented by a series of springs. On the other hand, in computer-aided continuum analysis, soil below the raft is modeled using solid elements available in finite element–based software. In the present study, analyses of the raft as a single unit and the raft together with the superstructure as a combined unit are carried out separately for a wide range of soil strength parameters employing the Winkler and continuum methods. The results of the analyses and subsequent designs were compared for different models. The variations in the quantity of reinforcement required for the raft and superstructure, corresponding to changes in soil stiffness values in different modeling methods, are investigated. Useful recommendations are presented to increase the effectiveness of Winkler model for structural design. The need for modeling the raft and superstructure as a combined unit is also highlighted.

Seismic performance evaluation of a pile-supported pier in Aceh, Indonesia

The seismic performance of shore structures located in regions having high seismicity is still attracted the interest of researchers. Earthquakes could bring about serious damages on the structures which might lead to failure. Thus the structures’ performance under the ground motions need to assessed. This paper describes results of study on performance of a pile supported pier which was constructed in Aceh, Indonesia under seismic motions. In this study the performance evaluation of the pier was conducted using displacement based method of ASCE 61-14 code. 3D numerical models of the pier structure were developed utilizing a structural analysis software package. To account for soil-structure interaction under simulated seismic loads, the nonlinear p-y spring model recommended by American Petroleum Institute was applied. Nonlinear static pushover analysis was performed to obtain structure’s capacity. Respons spectrum analysis and nonlinear static demand analysis were carried out to obtain the structure’s demand capacity. Results of this study showed that under the 475 and 950-year return periods of earthquakes, the pile-supported pier could be categorized as Minimal Damage. Nevertheless, when it was under 2475-year earthquake return period its performance could be categorized as Control and Repairable Damage; These met the requirements stated in ASCE 61-14.

Low cost CPU–GPGPU parallel computing in real-world structural engineering

Parallel computing has matured from a narrow academic environment, where researchers developed finite element computing tools for performing their studies, to become the basis in modern analysis and design procedures. Several software applications in recent years have made these computing environments accessible to professional engineers, researchers and students outside the computer science research community. These software applications, mainly focused on aerospace, aeronautical, mechanical and naval structural systems, have incorporated the parallel computing component as an additional capability of the finite element software package. On the other hand though, there is not a computational approach for dealing with real-world civil engineering structures such as buildings, bridges or more complex civil engineering structures taking advantage of the high-performance capabilities of contemporary personal computers. Furthermore, graphic processing units (GPUs) have lately been used as high performance co-processors for demanding computational tasks. In modern structural analysis software packages, a hybrid computing model can be implemented, according to which the GPU can be used as a co-processor in order to offload the system's central processing unit (CPU), and therefore increase the overall computational efficiency. SCADA Pro is a structural analysis and design technical software package which implements out-of-core direct and iterative sparse parallel solvers in order to provide high performance computing capabilities in real-world structural engineering. In the present work, real-world structural systems are analysed using SCADA Pro's high performance computing capabilities. The results and computational efficiency are discussed and compared among different solvers, single and multi-threaded CPU and GPU computations.

Investigation of Developed Thermal Forces in Long Concrete Frame Structures

The objectives of this paper are to review the modeling and design of concrete frame structures for the changing member-temperature loading case and the section gradient-temperature loading case. In addition, the intensity distribution of internal forces resulting from temperature changes and the factors that cause a decrease or increase in these forces was studied. When the temperature of an object changes positively or negatively, its length increases or decreases according to basic physical laws. If an object subjected to temperature change is restrained, internal compression or tension forces are created. Using temperature equations in a finite element structural analysis software package, deformation and internal forces were calculated for 2-D and 3-D frame buildings. In the member-temperature change loading case, conclusions were reached that no matter how high the structure is, only members such as beams and columns on the lowest two stories are substantially affected, but the greater the length or width of the structure, the greater are the force values on the affected members. In the section gradient-temperature loading case, it was observed that the most affected members were the beams on the upper two levels in addition to the facade columns; however, the output forces and moment values were small and sometimes negligible.

3D Flutter Analysis of Cable Supported Bridges Including Aeroelastic Effects of Cables

For 3D flutter analysis of cable supported bridges, the aeroelastic effects of cables include the aerodynamic forces acting on cables and local lateral vibrations of cables, as well as the interaction of both. In order to investigate the aeroelastic effects of cables, a 3D flutter analysis method by a commercial structural analysis software package is developed and verified by the simply supported thin plate example and two actual bridges. The developed method can treat the cable as a multi-link model, instead of a single link model, and therefore can show the lateral degrees of freedom along the cable. Also it can simulate the structural damping perfectly and solve the flutter modes successfully. The flutter behaviors including aeroelastic effects of cables of two example bridges, Yangpu Bridge and Jiangyin Bridge in China, are investigated based on the developed method. The calculated results show that for the Yangpu cable-stayed bridge with a 602 m main span, the flutter critical wind velocity can be increased by 20.2% with the consideration of aeroelastic effects of cables. For the Jiangyin suspension bridge of 1385 m main span, however, the impact of the aeroelastic effects of cables on the flutter critical wind velocity is neglectable. The mechanisms of the aeroelastic effects of cables are discussed in this paper.

Determination of the steady state response of portal frames with intermediate viscoelastic links

Steady state response of portal frames whose members are connected to each other continuously or by infinitesimally small rotational link elements (intermediate viscoelastic hinges) are investigated under a periodic external force within the Euler-Bernoulli beam theory by using energy based finite element method. The effect of damping of the members of portal frames, the values of rotational spring coefficient and damping coefficient of intermediate viscoelastic hinges on the steady state response are investigated numerically. Optimum damping coefficients of intermediate viscoelastic hinges are investigated for different damping coefficients of members. The results of frames constituted by connecting the members continuously and by connecting the members with intermediate viscoelastic hinges in some desired joints are compared and presented in graphics and tables. Convergence studies are made. The obtained results are compared with the results of same models constituted on the structural analysis software package SAP 2000. It is seen that the results obtained from this study are harmonious with the results obtained by using SAP 2000 package. Key words: Portal frames, finite element method, viscoelastic hinge, steady state response, optimum damping coefficients.

Effect of LRB isolators and supplemental viscous dampers on seismic isolated buildings under near-fault excitations

Base isolation is a quite sensible structural control strategic design in reducing the response of a structural system induced by strong ground motions. It is clear that the effects of near-fault (NF) ground motions with large velocity pulses can bring the seismic isolation devices to critical working conditions. In the present paper, nonlinear time history analyses were performed using a commercial structural analysis software package to study the influence of isolation damping on base and superstructure drift. Various lead-rubber bearing (LRB) isolation systems are systematically compared and discussed for aseismic performances of two actual reinforced concrete (RC) buildings. Parametric analysis of the buildings fitted with isolation devices is carried out to choose the appropriate design parameters. The efficiency of providing supplemental viscous damping for reducing the isolator displacements while keeping the substructure forces in reasonable ranges is also investigated.

Spreadsheet routine for the management of structural data with a microcomputer

Abstract The conventional structural analysis software packages are designed to compute complex algorithms and to draw accurate projections. However, they are lacking in their data-management capabilities. A routine, built on spreadsheet software, is presented here which can perform data selection and editing in a fully interactive single keystroke format in conjunction with the stereographic projection. The database is set by putting each measurement in different rows, along with geographical, lithological, and structural characteristics. Strike plus dip or azimuth plus plunge are transformed into X-Y values that can be plotted onto a graphic. Selections of the measurements are performed using logical formulae involving the attached characteristics.

Integrated software for mechanical CAE

This article gives details of the application of CAE methods and tools to the structural design of a Winchester disk drive conducted by SDRC using the I-DEAS mechanical CAE system. The approach described is not limited to disk drives, but has been applied successfully to a variety of products and systems. One of the innovations in the project was the use of specially defined structural elements which permit the modelling and analysis of active control systems within a commercial structural analysis software package. This alleviated the usual problems of using separate structural and control system analysis codes and therefore illustrates the level of integration achievable in CAE systems.

Predicting the random acoustic response of a complex structure using FEM techniques

Spacecraft built at RCA Astro undergo a sequence of environmental tests which include an acoustic test. Its purpose is to demonstrate the ability of the spacecraft and its components to withstand the acoustic vibration environment imposed on it during launch and transonic flight. This paper describes work done to predict the vibration response of the structure and of some critical components to the severe random acoustic excitation. Finite element techniques were used to model two different equipment panels and a typical stowed solar panel of the satellite. Using the STARDYNE structural analysis software package, the structural responses of these models were predicted. The random excitation capabilities of the program were used to excite the models in a way such as to best simulate the physical mechanisms for random acoustic excitation. The corresponding structural responses on the flight spacecraft were then measured during a flight simulation acoustic test in RCA's reverberation test facility. The predicted and measured responses are presented for comparison.