Seismic performance of single layer steel cylindrical lattice shells
TL;DR: In this paper, the elastic and inelastic seismic behavior of single layer steel cylindrical lattice shells is examined through a parametric assessment, which also leads to proposed expressions for estimating the fundamental period and mode of vibration.
Abstract: This paper examines the elastic and inelastic seismic behaviour of single layer steel cylindrical lattice shells. The main dynamic characteristics for this form of structure are firstly examined through a parametric assessment, which also leads to proposed expressions for estimating the fundamental period and mode of vibration. The seismic response of five typical shell configurations, representing a wide range of rise to span ratios, is then assessed within the linear elastic range under selected earthquake excitations. Particular focus is given to the relative influence of the horizontal and vertical seismic components on the internal actions. In order to provide a means for evaluating the underlying inelastic behaviour, a simple pushover approach, which is suitable for this structural form, is suggested using the forces obtained from the fundamental mode shape. The peak angle change is proposed as a damage parameter within the nonlinear analysis for characterising the inelastic global and local demands in shells of different geometries. Incremental dynamic analysis is subsequently carried out in order to evaluate the detailed nonlinear time history response. The results provide detailed insights into the influence of the horizontal and vertical excitations on the nonlinear seismic response, and illustrate the suitability of the peak angle change as an inelastic deformation measure for shells of different geometric configurations. The main findings from the linear and nonlinear assessments are highlighted within the discussions, with a view to providing guidance for performance based assessment procedures as well as simplified design approaches.
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TL;DR: In this article, an experimental investigation into confinement effects provided by circular tubular sections to rubberised concrete materials under combined loading is described. But the main focus is given to assessing the confinement effects in the infill concrete as well as their influence on the axial bending cross-section strength interaction.
Abstract: This paper describes an experimental investigation into confinement effects provided by circular tubular sections to rubberised concrete materials under combined loading. The tests include specimens with 0%, 30% and 60% rubber replacement of mineral aggregates by volume. After describing the experimental arrangements and specimen details, the results of bending and eccentric compression tests are presented, together with complementary axial compression tests on stub-column samples. Tests on hollow steel specimens are also included for comparison purposes. Particular focus is given to assessing the confinement effects in the infill concrete as well as their influence on the axial–bending cross-section strength interaction. The results show that whilst the capacity is reduced with the increase in the rubber replacement ratio, an enhanced confinement action is obtained for high rubber content concrete compared with conventional materials. Test measurements by means of digital image correlation techniques show that the confinement in axial compression and the neutral axis position under combined loading depend on the rubber content. Analytical procedures for determining the capacity of rubberised concrete infilled cross-sections are also considered based on the test results as well as those from a collated database and then compared with available recommendations. Rubber content-dependent modification factors are proposed to provide more realistic representations of the axial and flexural cross-section capacities. The test results and observations are used, in conjunction with a number of analytical assessments, to highlight the main parameters influencing the behaviour and to propose simplified expressions for determining the cross-section strength under combined compression and bending.
10 citations
TL;DR: In this article, a two-way aluminum alloy cable-stiffened single-layer latticed shell is proposed to explore a shape optimization procedure of such structure, and the buckling behavior of the optimized structures and classic cylindrical latticed shells are examined and compared.
Abstract: The circumferential profile of cylinder, as a classic shape, has been widely adopted in single-layer latticed shells. Previous research into these structures primarily concentrated on their buckling behavior. In this work, a novel two-way aluminum alloy cable-stiffened single-layer latticed shell is proposed to explore a shape optimization procedure of such structure. In addition, the buckling behavior of the optimized structures and classic cylindrical latticed shells are examined and compared. The optimization procedure adopts a linear algorithm, in which the structural strain energy is selected to be the optimization objective. Buckling analyses are also performed to compare the buckling behavior of this novel latticed shell with classic cylindrical and optimized shapes. The comparisons show that the load-carrying capacities are clearly enhanced by optimizing the shell shapes. The results presented in this article are anticipated to aid engineers in the design of two-way aluminum alloy latticed shells with an optimal shape.
10 citations
TL;DR: The assessments presented in this paper can also be used to support detailed performance based guidelines as well as for informing geometry and size optimisation strategies.
Abstract: This paper examines the main considerations related to the seismic design and assessment of single layer steel cylindrical lattice shells, and offers recommendations for their practical application. Geometric configurations covering a wide range of rise to span ratios are considered within the investigation. An insight into the relative influence of seismic loading on shell design, in comparison to gravity conditions, is firstly provided through the use of digital parametric engineering procedures. This is followed by linear elastic response assessments which are used to propose a simplified procedure for estimating the internal seismic forces for the purpose of member sizing in early design stages. Suitable approaches for pushover analysis are then discussed and used to identify inherent plastic mechanisms. The results of incremental nonlinear dynamic analysis, using a suite of fourteen records, are also employed in order to validate the findings and to further assess the ultimate response under realistic seismic loading conditions. Based on the findings, representative ranges for behaviour factors and displacement modification coefficients are derived alongside discussions on their implementation within codified seismic design procedures. Apart from providing recommendations for simplified design approaches, the assessments presented in this paper can also be used to support detailed performance based guidelines as well as for informing geometry and size optimisation strategies.
6 citations
TL;DR: In this article, a parametric study was conducted on steel gridshell domes with 60, 100 and 150m spans and six-storey substructures to investigate the interaction between the higher substructure modes and dominant roof modes.
Abstract: The seismic response of gridshell roofs with substructures is strongly influenced by the relative mass and stiffness of the roof and substructure, and particularly by how close the periods of the dominant roof and substructure modes are. Multistorey substructures may exhibit a significant higher-mode acceleration response, primarily due to the contribution of the shorter second translational substructure mode to the roof response. This paper presents parametric studies conducted on steel gridshell domes with 60, 100 and 150 m spans and six-storey substructures to investigate the interaction between the higher substructure modes and dominant roof modes. The contribution of each substructure mode to the overall response was characterised by a newly proposed dominance response ratio. In contrast to previous studies of long-period single-storey substructures, which only minimally excited the roof modes, the higher modes of the long-period multistorey substructures investigated in this study significantly contributed to the roof response. The roof vertical accelerations were amplified by up to three times the substructure roofline acceleration, as the curved roof geometry couples the horizontal substructure and vertical roof response. The substructure higher-mode contribution was quantified using amplification factors and developed into equivalent static loads that were found to be in good agreement with response spectrum analysis results. The proposed equivalent static loads provide insight into the complex dynamic characteristics of gridshell roofs with multistorey substructures and offer an efficient method for preliminary seismic design.
5 citations
TL;DR: In this paper , a method to express statically equivalent seismic loads based on the two dominants modes with emphasis on single-layer reticulated shells encompassing spherical, cylindrical, and free-form shells was discussed.
Abstract: The present study discusses a method to express statically equivalent seismic loads based on the two dominants modes with emphasis on single-layer reticulated shells encompassing spherical, cylindrical, and free-form shells. The shells investigated are shallow roofs of three-way member arrangement. For the earthquake response analysis, a set of twelve artificial earthquake motions are introduced compatibly with the design response spectrum specified in the building code of Japan. First, to analyze the response behavior and to find the relationship between the shell geometries and their vibrational properties, a vibration database is set up based on the response spectrum method using the results obtained from eigenvalue analysis. Second, an analysis of pseudo-seismic energy and mass ratios of free vibration modes is performed to discuss what have important roles in estimating the equivalent seismic loads. Third, from a viewpoint of the two-mode-based aaproach, the importance of the pseudo-seismic energy is discussed, then followed by a proposal of the equivalent seismic loads for the reticulated shell roofs. Finally, the validity of the proposed formation is confirmed under a certain restraint to its application.
3 citations
References
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TL;DR: Incremental dynamic analysis (IDA) is a parametric analysis method that has recently emerged in several different forms to estimate more thoroughly structural performance under seismic loads as mentioned in this paper, which involves subjecting a structural model to one or more ground motion record(s), each scaled to multiple levels of intensity, thus producing one (or more) curve(s) of response parameterized versus intensity level.
Abstract: Incremental dynamic analysis (IDA) is a parametric analysis method that has recently emerged in several different forms to estimate more thoroughly structural performance under seismic loads. It involves subjecting a structural model to one (or more) ground motion record(s), each scaled to multiple levels of intensity, thus producing one (or more) curve(s) of response parameterized versus intensity level. To establish a common frame of reference, the fundamental concepts are analysed, a unified terminology is proposed, suitable algorithms are presented, and properties of the IDA curve are looked into for both single-degree-of-freedom and multi-degree-of-freedom structures. In addition, summarization techniques for multi-record IDA studies and the association of the IDA study with the conventional static pushover analysis and the yield reduction R-factor are discussed. Finally, in the framework of performance-based earthquake engineering, the assessment of demand and capacity is viewed through the lens of an IDA study. Copyright © 2001 John Wiley & Sons, Ltd.
3,334 citations
"Seismic performance of single layer..." refers methods in this paper
...Finally, to evaluate the validity of the peak angle change as a useful damage indicator, as well as the adopted pushover analysis procedure for predicting the inelastic behaviour, the different limit points are compared from the pushover and IDA....
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...This is illustrated in Figure 33, showing the individual points for the IDAs as well as the median values as vertical dashed lines, compared to the predicted values from the pushover analysis indicated as vertical solid lines....
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...The peak angle change at which first yield in the edge arch occurs was obtained from each individual analysis from the IDA including both horizontal and vertical components....
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...To assess the nonlinear behaviour under realistic earthquake loading, the response of the same five shells described above was examined through incremental dynamic analysis (IDA) [57, 58]....
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...Rearranging these values, and considering the scaling factors used in the IDA, the corresponding intensity factor, _′, can be obtained....
[...]
Book•
14 Jun 2010
TL;DR: In this paper, the authors defined a set of criteria for the verification of the stability of members with plastic hinges, including tension, tension, compression, and buckling resistance of non-prismatic members.
Abstract: INTRODUCTION General Observations Codes of Practice and Normalization Basis of Design Ultimate limit states Serviceability limit states Durability Sustainability Materials Material specification Mechanical properties Toughness and through thickness properties Fatigue properties Corrosion resistance Geometric Characteristics and Tolerances STRUCTURAL ANALYSIS Structural Modelling, Worked Examples Global Analysis of Steel Structures, Worked Examples Classification of Cross Sections DESIGN OF MEMBERS Tension, Worked Examples Laterally Restrained Beams, Worked Examples Torsion, Worked Examples Compression, Worked Examples Laterally Unrestrained Beams, Worked Examples Beam-Columns, Worked Examples ELASTIC DESIGN OF STEEL STRUCTURES Simplified Methods of Analysis Amplified sway-moment method Sway-mode buckling length method Worked Example Member Stability of Non-prismatic Members and Components Non-prismatic members Members with intermediate restraints General method Worked Example Design Example 1: Elastic Design of Braced Steel-Framed Building PLASTIC DESIGN OF STEEL STRUCTURES 345 General Rules for Plastic Design Plastic limit analysis: method of mechanisms Code requirements for plastic analysis Methods of Analysis Approximate methods for pre-design Computational analysis 2nd order effects Worked Example Member Stability and Buckling Resistance General criteria for the verification of the stability of members with plastic hinges Bracings Verification of the stability of members with plastic hinges Worked Examples Design Example 2: Plastic Design of Industrial Building REFERENCES
1,143 citations
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TL;DR: The NGA-West2 project database as mentioned in this paper includes ground motion data recorded from shallow crustal earthquakes in active tectonic regimes post-2000 and a set of small-t...
Abstract: The NGA-West2 project database expands on its predecessor to include worldwide ground motion data recorded from shallow crustal earthquakes in active tectonic regimes post-2000 and a set of small-t...
800 citations
"Seismic performance of single layer..." refers methods in this paper
...Seven natural records were selected for the time history analyses from the PEER NGA West database [48], from events occurring in Europe and the Middle East....
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Book•
01 Jan 1983TL;DR: This book tackles the fundamental question of how bending and stretching effects combine and interact in shell structures from a physical point of view; and it shows that this approach leads to an understanding of the structural mechanics of shells in general, and to useful results in particular problems.
Abstract: Shell structures form key components in a very wide range of engineering enterprise. The theory of shell structures is an old and large subject, with a huge literature. However, this book is not a compilation of results from the past. Instead, it is an attempt to bring the essence of the subject within the grasp of engineers. It tackles the fundamental question of how bending and stretching effects combine and interact in shell structures from a physical point of view; and it shows that this approach leads to an understanding of the structural mechanics of shells in general, and to useful results in particular problems. The first half of the book is concerned mainly with the basic ideas and equations of equilibrium, geometry and elasticity, and their combination in various useful ways. In particular, it includes a simple treatment of the geometry of general curved surfaces. The second half of the book first investigates the behaviour of various practical shell structures under static loading. Then there are chapters on the buckling of shells, on vibration, and on the application of plastic theory to analysis and design.
663 citations
TL;DR: A practical and detailed example of how to perform incremental dynamic analysis (IDA), interpret the results and apply them to performance-based earthquake engineering is presented.
Abstract: We are presenting a practical and detailed example of how to perform incremental dynamic analysis (IDA), interpret the results and apply them to performance-based earthquake engineering IDA is an emerging analysis method that offers thorough seismic demand and capacity prediction capability by using a series of nonlinear dynamic analyses under a multiply scaled suite of ground motion records Realization of its opportunities requires several steps and the use of innovative techniques at each one of them Using a nine-story steel moment-resisting frame with fracturing connections as a test bed, the reader is guided through each step of IDA: (1) choosing suitable ground motion intensity measures and representative damage measures, (2) using appropriate algorithms to select the record scaling, (3) employing proper interpolation and (4) summarization techniques for multiple records to estimate the probability distribution of the structural demand given the seismic intensity, and (5) defining limit-s
498 citations
"Seismic performance of single layer..." refers methods in this paper
...Finally, to evaluate the validity of the peak angle change as a useful damage indicator, as well as the adopted pushover analysis procedure for predicting the inelastic behaviour, the different limit points are compared from the pushover and IDA....
[...]
...This is illustrated in Figure 33, showing the individual points for the IDAs as well as the median values as vertical dashed lines, compared to the predicted values from the pushover analysis indicated as vertical solid lines....
[...]
...The peak angle change at which first yield in the edge arch occurs was obtained from each individual analysis from the IDA including both horizontal and vertical components....
[...]
...To assess the nonlinear behaviour under realistic earthquake loading, the response of the same five shells described above was examined through incremental dynamic analysis (IDA) [57, 58]....
[...]
...Rearranging these values, and considering the scaling factors used in the IDA, the corresponding intensity factor, _′, can be obtained....
[...]