Steel Structure Model Research Articles

Artic Determination of Dynamic Characteristics the Structure with ARX and ARMAX Estimation Methods

In this study, the dynamic behavior of a single-span four-storey steel model structure is tried to determine by using 2 different methods. Connections between beams and columns are produced as rigid and the structure is connected to the shake table by a fixed support. In order to measure the forced vibration values applied to the model structure with the help of the shaking table, the smartphone was placed on the shaking table base and the top of the steel model structure and acceleration records were taken. After the records have been processed, structural algorithm is created using MATLAB autoregressive ARX and autoregressive moving average ARMAX models. Smartphone records from the shake table are defined as inputs and smartphone from the top of the structure are defined as outputs in MATLAB autoregressive ARX and autoregressive moving average ARMAX models. By doing this, structure’s dynamic behavior is to be obtained by MATLAB autoregressive ARX and autoregressive moving average ARMAX models when only vibrating table acceleration record is inputted. Dynamic characteristics obtained by ARX and ARMAX were tried to be confirmed by finite element method using Sap2000 software. In order to determine the dynamic characteristics of the building, the earthquake records of Kobe, Sakarya, Loma-Priate and El-Centro were used as forced vibration. At the end of the study, dynamic properties obtained by numeric models (ARX and ARMAX) using input acceleration record are compared to the dynamic properties obtained by Sap2000 analysis. By doing this it was determined whether dynamic properties can be reliably obtained using autoregressive ARX and autoregressive moving average ARMAX models. Advantages and disadvantages of using this method to define structural behavior are discussed.

Assessment and Design of Steel frame Structure, consists Performance of Connection Joints with Tekla & Staad Pro

Steel offer the range of advantages to the structure Industry. The erudition of steel gives architects, and the freedom was to achieve the most ambitious visions. Steel is also one of the most sustainable construction materials, building owners naturally value the flexibility of steel buildings in addition the value of benefits they provide. Steel is ideal for modernization, reconfiguring, extending or adapting with minimal disruption. The conception of design analysis as well as modelling of steel structures is the most up-to-date edition in the civil engineering field. It is necessary to model a steel structure but if it is also analysed during its modelling then there will not be any chances of failure. Tekla structures are powerful and flexible software for all structural projects. Flurry up our construction work with an enormous of standard connections for all structural projects. In construction field, we create a evident, constructible 3D model of any steel structure from everyday industrial and commercial buildings to stadiums and high rise buildings. This project dealing with manual connection designing by using of Standards (ISO, AISC, AWS etc..). As well as considering of OSHA rules. Implemented manual designing and modelling by using of Tekla software. And the connections are an important part of steel structure like beam to column connections, moment connections. And are designed more conventionally than any individual members. The aim of this project work is to analyse a 7-storeyed commercial building for different load combinations using STAAD Pro software. And behaviour of connection of bolts.

The mutual interaction between the structural footprint and number of floors in steel structures

Structural dimensions and number of floors are some of the factors affecting the building behaviour under the earthquake effects. In this study, the structural footprint and the number of floors were selected as a variable. For this purpose, a steel structure model with fixed dimensions and properties of load-bearing system elements was selected. The structural footprint was selected as the first variable and then five different structure models were created. The structural footprint was changed by setting each axial clearance in both directions. Each axial clearance was increased by 0.5m in each structure model. Three different number of floors as to be 5, 6 and 7 floors were selected as the second variable. Eigenvalue and pushover analyses were performed for each model and each number of floors. As a result of the analyses, the target displacement values for period, frequency, cumulative participation mass ratio, base shear force, settlement, stiffness and degree of damage were acquired separately. As the structural footprint and number of the floors increase, while the period, settlement and the target displacement values increased, on the contrary, there was a decrease in participation mass ratio, base shear forces and stiffness values. In the study, cost comparisons of building construction were also made considering the change in the total structural area and the number of floors. The criterion of safety and economy was ignored due to increase both in the number of floors and the footprint. This study emphasizes the importance of avoiding the unnecessary structural dimensions via optimum design principles. As structural footprint area and number of floors increase, period values increase, stiffness and seismic capacity values decrease. As the number of floors and footprint area increases, the total building area increases, so the approximate building cost has also increased.

Laser welding and its implementation in the assembly of battery packs in aviation

Following an overview of conventional bonding techniques used for the assembly of battery packs of modern hybrid vehicles special attention will be paid to laser keyhole welding. The unique challenges of aviatic applications, especially joining large number of batteries in a highly reproducible manner are pinpointed. The effect of contact area on the electrical and mechanical properties of laser welded joints is investigated on a DC01 steel model structure. The results are also discussed in terms of laser scanning speed. In the optimal process parameter range joints exhibiting electrical and mechanical properties appealing for assembling hybrid aircraft battery packs can be produced with high reproducibility.

DAMAGE LEVEL PREDICTION OF MULTI-STORY STEEL STRUCTURE IN SUMATRA USING BACKPROPAGATION NEURAL NETWORK

Sumatra is one of the Indonesia islands that is prone to earthquakes both tectonic and volcanic. The research aims to predict the damage level of a multi-story steel structure due to the earthquake in Sumatra Island using the Backpropagation Neural Network (BPNN). The study used the steel structure building that received earthquake loads from ten capital cities of the province on Sumatra Island. The structure analysis used the finite element software while the BPNN method used the MATLAB Programming. The input data were the responses of the structure such as displacement, velocity, and acceleration while the output was damage level of the steel structure model. The model of BPNN has the potential accuracy to predict the damage level of steel structural more than 95%. According to the simulation result, 98,5% data could be predicted correctly by the BPNN method, and the best Mean Squared Error (MSE) is 0.028. These results have shown that BPNN can predict the damage level of multi-story steel structure in all the capital cities of the province on Sumatra Island.

Fire Protection of Steel Structures by Low Pressure Water Mist in Large-Scale Fire Test

Water mist extinguishing systems are becoming more popular due to their much higher fire-fighting efficiency at lower water consumption compared to conventional sprinklers. The article focuses on the possibility of further utilization in a form of cooling structures and presents the results of a research in the area of low-pressure water mist and the development of a new low-pressure water mist cooling system. It also introduces a new possible direction for application of cooling steel structures or their surroundings in order to increase fire resistance of steel structures. To verify the cooling effects of low-pressure water mist, a large-scale fire test with a model of steel roof construction was carried out in a room with dimensions of 4.0 × 4.0 × 2.0 m. The fire test was conducted in two scenarios. The first scenario is a reference test without application of water mist, where temperatures of the burning room and steel structures are monitored. Compared to the first scenario, the second scenario includes the use of low-pressure water mist protection of the steel structure model at the time of full fire development.

Dark Matter Garden: A case study in algorithmic modelling and digital fabrication of complex steel structures

This paper is focusing on the application of algorithmic modelling techniques to represent, design and fabricate gravitational lens effects (as described by the astrophysical theory of the ‘Dark Matter’) in form of a garden pavilion for the Royal Horticultural Society's, Chelsea Flower Show. In addition, this research-led project is exploring the challenges occurring in the use of three-dimensional CNC bending technologies. This is a research by design project and its method is based on a design framework, which incorporates a generative algorithm linked to feedback loops related to parameters such as laws of gravity, plot dimensions, materiality, positioning of the plants, construction and fabrication, requirements and cost as well as the overall aesthetics. Its findings are highlighting accomplishments and failures of a file to factory design and fabrication process, which incorporates algorithmic modelling and digital manufacturing techniques in a collaborative environment. The ‘Dark Matter Garden’ installation was awarded the gold medal for ‘Best Fresh Garden’ by the Royal Horticultural Society in 2015.

Experimental Study on Behavior of Bench-Scale Steel Structure Retrofitted with CFRP Composites under Ambient Vibration

Usage of FRP composites for the retrofitting purpose of the structures against the harmful effect of dynamic loads are gaining popularity, it is used in a wide variety of disciplines including civil engineering. Thus, there is a great need to study the behavior of FRP composites for strengthening purposes of structures using empirical methods. In this study, a bench-scale steel structure model was strengthened with CFRP composite and tested using operational modal analysis. To conduct operational modal analysis a bench-scale earthquake simulator and ambient vibration emulator were used. Same steel structure model was tested without strengthening procedure. Obtained dynamic responses (maximum-minimum displacements and accelerations before and after application of CFRP) of steel structure model have compared to each other. This study shows that floor displacements of the model have been decreased along the height of the structure up to 41.43 %. Therefore, the results of the experiment confirm the effectiveness CFRP composites for the strengthening of steel structures.

Experimental Study on Behavior of Bench-Scale Steel Structure Retrofitted with CFRP Composites under Ambient Vibration

Usage of FRP composites for the retrofitting purpose of the structures against the harmful effect of dynamic loads are gaining popularity, it is used in a wide variety of disciplines including civil engineering. Thus, there is a great need to study the behavior of FRP composites for strengthening purposes of structures using empirical methods. In this study, a bench-scale steel structure model was strengthened with CFRP composite and tested using operational modal analysis. To conduct operational modal analysis a bench-scale earthquake simulator and ambient vibration emulator were used. Same steel structure model was tested without strengthening procedure. Obtained dynamic responses (maximum-minimum displacements and accelerations before and after application of CFRP) of steel structure model have compared to each other. This study shows that floor displacements of the model have been decreased along the height of the structure up to 41.43 %. Therefore, the results of the experiment confirm the effectiveness CFRP composites for the strengthening of steel structures.

Cooperation between Weimar and Budapest on computational modelling of steel and composite structures

AbstractDedicated to Univ.‐Prof. Dr.‐Ing. habil. Frank Werner on his 70th birthdayZusammenarbeit zwischen Weimar und Budapest bei der rechnergestützten Modellierung von Stahl‐ und VerbundkonstruktionenDer Beitrag gibt einen Überblick über die langjährige Zusammenarbeit zwischen der Bauhaus‐Universität Weimar und der Budapester Universität für Technik und Wirtschaft bei der rechnergestützten Modellierung von Tragwerken. Die Zusammenarbeit umfasst verschiedene Elemente der Forschungsaktivitäten, die Entwicklung experimenteller und numerischer modellbasierter Bemessungsmethoden für innovative Tragwerkdetails von Industriehallen, die bilaterale Ausbildung von Studierenden auf verschiedenen Ebenen (BSc, MSc und PhD) sowie die gemeinsame Betreuung von Doktoranden und Gutachten zu Dissertationen. Die fruchtbare Zusammenarbeit ist das Resultat der freundschaftlichen Beziehung von Prof. Frank Werner und Prof. László Dunai, die den überwiegenden Teil der gemeinsamen Forschungs‐ und Lehrtätigkeit organisiert und geleitet haben. Die gemeinsam erarbeiteten Forschungsergebnisse haben den Wissensstand über die Bemessung von Dachtragwerken mit dünnwandigen Profilen für Industriehallen, über die Auslegung von Schubverbindern kaltgeformten Verbundblechen und über die Modellierung zyklischer Plastizität erweitert. Studenten aus Ungarn hatten die Gelegenheit, im Rahmen von durch Prof. Werner organisierten Summer Schools an der Bauhaus‐Universität Weimar zu studieren. Darüber hinaus betreute er zwei ungarische Doktoranden in Weimar, und ein deutscher Doktorand verbrachte einen Forschungsaufenthalt in Budapest unter der Leitung von Prof. Dunai. Der vorliegende Beitrag bietet zu Ehren des 70. Geburtstags von Prof. Frank Werner einen Überblick über die wichtigsten Aktivitäten und Ergebnisse dieser zwei Jahrzehnte währenden Zusammenarbeit. Sie alle befassen sich mit der rechnerischen Modellierung von Stahl‐ und Verbundkonstruktionen.

Stability Analysis of Steel Structure Model Based On the Finite Element Method

In this paper, the traditional method is used to solve the uncertainty of steel structure. Different stiffness of beams and columns are adopted. The lateral displacement modes of steel structure under symmetrical load are analysed, and the buckling load is obtained. The calculated length coefficient is further obtained. The results are compared with those obtained by traditional displacement method, which provides a reference for the application of finite element method and displacement method in the stability of steel structure.

Method of Pushunder Analysis (PUA) for Approximate Seismic Analysis of Structures Using Various Patterns of Stepwise Increasing Base Acceleration and Its Comparison with Pushover Analysis (POA)

In this paper, a new simple semi-dynamic method is introduced for the approximate evaluation of the seismic behavior of steel structures which is called Pushunder Analysis (PUA). In this method incrementally increasing horizontal unidirectional and reciprocal base acceleration in saw-tooth patterns, which increases from zero to a specified maximum value is applied to the base of a model structure for analysis of its response using the method of Time History Analysis (THA). This method is compared with conventional Pushover Analysis (POA), where incrementally increasing code specified lateral load patterns are applied to the floors of a model structure. The main objective of this paper is to obtain which one of these two methods (POA and PUA) can better represent the seismic behavior of the structure more accurately. For this purpose, the results of the semi-dynamical PUA of a ten story steel structure model are obtained using various patterns of base acceleration. These results are: total displacement, relative drifts, shear story in linear range and P-Δ type curves in nonlinear range for each selected base acceleration patterns which are shown and compared with POA results. To verify the degree of the accuracy and the peculiarities of this method, the linear and nonlinear responses of the model structure under: static UBC-97 standard seismic loading, dynamic El Centro 1979 acceleration records and FEMA-461 cyclic displacement (which was converted to analogous base accelerogram) are compared with the similar responses obtained by the POA and PUA methods. In general, the proposed PUA method needs further evaluation and case studies to ascertain its merits; however, it shows considerable potential and advantages due to its consideration of dynamical and torsional effects and hysteresis properties of structures. The sensitivities of this method to the length of dynamic time steps of calculation and the forms and durations of the saw-tooth oscillations are discussed and it is found that by the proper choice of these parameters, better results can be obtained.

15.09: High‐resolution modelling and design of steel structures

ABSTRACTThe art and science of structural engineering has always required a balance between predicting the demands on a structure and making sure that those demands can be met with the structure's strength and stiffness. Historically, analytical models have been used to predict demands and codified design equations have been used to predict strength. Over the past approximately 50 to 60 years, finite element analytical models have evolved from crude first‐order linear representations made up of dozens of degrees of freedom to sophisticated second‐order nonlinear models made up of hundreds of thousands of elements. With the ever increasing capability of personal computing and the ability to construct more and more sophisticated finite element models, new approaches to the design of steel structures that were once thought impossible are becoming realistic.State of the art a decade ago was to employ models constructed from discrete one‐dimensional elements based on nominal geometry and linear material behaviour. Influences and behaviours such as residual stresses, initial imperfections, buckling, fracture, and second‐order effects were addressed by codified design specifications, often in the form of tedious hand calculations. Exponential increases in computing power now permit entire structures to be represented using shell or solid elements and explicit modelling of influences such as residual stresses and initial imperfections. As a result, the balance between analysis and design can change. With modern sophisticated computer analyses, the balance can be shifted towards the analysis side of the equation leaving less work in the strength determination. With a model like the one described above, strength could be defined simply as yielding or as the development of a numerical singularity resulting from a loss of stiffness representing buckling or fracture.This paper outlines ongoing work towards developing guidelines for high‐resolution computer modelling of steel structures and rebalancing the treatment of phenomena between the analysis side and the design side of the equation.

07.38: A GBT‐framework towards modal modelling of steel structures

ABSTRACTIn modern structural steel frame design, the modelling of joints between beams and columns are based on very simple assumptions. The joints are most often assumed to behave as a perfect hinge or as a rigid joint. This means that in the overall static analysis relative rotations and changes in the moment curves due to joint deformations are neglected. This simplification eases the modelling but it is at the cost of losing a detailed understanding of the behaviour of the joint. This happens even though the European code has introduced the so‐called component method in order to determine the rotational stiffness of a connection. Based on a modelling of any beam‐to‐column joint using finite shell elements and springs for single components such as bolts, it is the primary hypothesis that it is possible to formulate a generalized connection model with few degrees of freedom related to a relevant set of deformation modes. This hypothesis is based on the idea of modal decomposition performed in generalized beam theories (GBT). The question is – is it possible to formulate an eigenvalue problem with a solution corresponding to mode shapes for the deformation of the joint by using the finite element model and some type of GBT beam elements? It is believed that this is possible. The paper will address our investigations and show the progress of our research.

Structural Behaviour of Steel Building with Diagonal and Chevron Braced CBF (Concentrically Braced Frames) by Pushover Analysis

This paper presents diagonal and chevron braced steel structure design with pushover analysis conducted following ATC-40 guidelines. In this study, the lateral load used is increased gradually until plastic hinge and collapse occur. The results are capacity curve, performance point, and the process of plastic hinge until the building collapse. There are five steel structure models designed based on the various types of bracing and bracing configuration. Model 1 is steel structure without bracing, model 2 and 3 are chevron braced steel structure, model 4 and 5 are diagonal braced steel structure. The results of this study indicate that the performance level of five models structure for earthquake in x direction and y direction according to ATC-40 is IO (Immediate Occupancy). Model 4 has the best effectiveness in terms of plastic hinge mechanism compared to other models. In the last step, model 4 is able to reduce plastic hinge 84% from model 1 for earthquake in x direction and 79% from model 1 for earthquake in y direction. Model 3 has the greatest ability to carry the forces of an earthquake compared to other models. It is 185% bigger than model 1 for x direction and 181% bigger than model 1for y direction. Model 3 has the greatest effectiveness in reducing lateral displacements compared to other models in the amount of 65.47% of model 1 for x direction and 72.14% of model 1 for y direction. Model 3 has the greatest effectiveness in reducing storey drift compared to other models in the amount of 73.89% of model 1 for x direction and 80.55% of model 1 for y direction.

Pairwise graphical models for structural health monitoring with dense sensor arrays

Through advances in sensor technology and development of camera-based measurement techniques, it has become affordable to obtain high spatial resolution data from structures. Although measured datasets become more informative by increasing the number of sensors, the spatial dependencies between sensor data are increased at the same time. Therefore, appropriate data analysis techniques are needed to handle the inference problem in presence of these dependencies. In this paper, we propose a novel approach that uses graphical models (GM) for considering the spatial dependencies between sensor measurements in dense sensor networks or arrays to improve damage localization accuracy in structural health monitoring (SHM) application. Because there are always unobserved damaged states in this application, the available information is insufficient for learning the GMs. To overcome this challenge, we propose an approximated model that uses the mutual information between sensor measurements to learn the GMs. The study is backed by experimental validation of the method on two test structures. The first is a three-story two-bay steel model structure that is instrumented by MEMS accelerometers. The second experimental setup consists of a plate structure and a video camera to measure the displacement field of the plate. Our results show that considering the spatial dependencies by the proposed algorithm can significantly improve damage localization accuracy.

Numerical Evaluation of Dynamic Response of a Steel Structure Model Under Various Seismic Excitations

The present paper reports the results of the study, which was designed to perform a numerical evaluation of dynamic response of a single-storey steel structure model. The experimental model was previously subjected to a number of different earthquake ground motions during an extensive shaking table investigation. The analyzed structure model was considered as a 1-DOF system with lumped parameters, which were determined by conducting free vibration tests. In order to solve the dynamic equation of motion, Newmark's average acceleration method was adopted. The results obtained from the numerical analysis confirm the accuracy in assuming lumped parameters to characterize the analyzed single-storey structure.

Investigation on Damage-Involved Structural Response of Colliding Steel Structures during Ground Motions

Earthquakes are the most unpredictable damaging loads which can affect civil engineering structures. Due to insufficient separation distance between adjacent structures with different dynamic properties, structural collisions may occur during ground motions. Although the research on structural pounding has recently been much advanced, the studies have mainly been conducted for concrete structures. The aim of this paper is to show the results of experimental investigation, focused on dynamic behaviour of closely-separated three models of steel structures which have been subjected to damaging earthquake excitations. The study was performed using three models of steel towers with different dynamic parameters and various distances between the structures. The acceleration time histories of the Kobe and the Northridge earthquakes were applied as the seismic excitation. The unidirectional shaking table, located at the Gdansk University of Technology (Poland), was used in the experimental study. The results have confirmed that collisions may lead to the increase in the structural response, although they may also play a positive role, depending on the size of the separation gap between the structures.

Problems of Collisions Between Adjacent Steel Structures under Earthquake Excitation / Problemy Zderzeń Pomiędzy Sąsiadującymi Konstrukcjami Stalowymi Poddanymi Obciążeniom Sejsmicznym

Abstract Nowadays, the high level of urbanization forces the engineers to design closelyseparated structures and to take into account many factors influencing their response, including collisions between them due to insufficient separation distance during moderate to strong ground motions. Recent observations as well as experimental and numerical investigations have confirmed that interactions between structures may lead to significant damage of structural elements and even to its total collapse. The aim of this paper is to investigate the influence of collisions between three insufficiently separated models of steel structures on structural response under earthquake excitation. The experimental tests as well as numerical analyses have been conducted in the study.

CONSIDERATIONS ON THE DIFFUSE SEISMICITY ASSUMPTION

Second-order effects were historically included by the effective length method (K concept). All the studies about that methodology have been developed in frame plane, with regular rectangular frames. The new way to include those effects is the use of second-order analysis, direct analysis method or alternative simplified options. This methodology was included in ANSI AISC360 in the 2005 version and in the 2010 version. As before, the studies already developed for DAM analysis are in plane. In this paper, the K concept is revisited by numerical analysis, and extended to the 3D space. Using models of symmetric and non-symmetric industrial steel structures in plane, 3D stability analyses were developed, and the results were compared with plane behavior. Several conclusions and recommendations were exposed, resulting from the analyzed models. Keywords: Second-order analyses, steel structures, irregular 3D frames.