Assessment and design considerations for single layer cylindrical lattice shells subjected to seismic loading
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.
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TL;DR: In this article , an effective damage detection method based on the combined modal strain energy index is proposed to detect the location of the damaged members in a single-layer latticed shells.
Abstract: The existing damage detection methods are challenging to be directly applied to single-layer latticed shells due to the complex mechanical mechanism and modal characteristics of such structures. In this regard, an effective damage detection method based on the combined modal strain energy index is proposed in this paper to detect the location of the damaged members in such structures. Based on the vibration modal features before and after damage of structures, the modal matching and combination method is presented to generate the combined mode, which include the modal matching procedure based on the modal assurance criterion and the modal combination procedure using the Kriging interpolation. Compared with the damaged mode, the specially constructed combined mode can significantly reduce the mode shape discrepancy in the undamaged region on the basis of retaining the characteristic differences in the damaged members. On this basis, the combined modal strain energy change index is proposed according to the modal strain energy difference between the original mode and the combined mode. Since the proposed index is established according to the difference between the combined vibration mode and the original vibration mode, the values of damage index of the undamaged members are greatly reduced, so as to effectively avoid the occurrence of misjudgement. Several numerical examples with different damage scenarios are studied in order to evaluate the proposed approach. The results clearly indicate that the proposed method features high damage localization accuracy compared with traditional methods and good measurement noise robustness.
10 citations
TL;DR: In this article , the seismic performance of an aluminum alloy honeycomb plate cylindrical reticulated shell structure was investigated by modal analysis and time-procedure analysis.
Abstract: In previous research, an aluminum alloy honeycomb plate cylindrical reticulated shell structure was designed. The bearing capacity test and numerical analysis show that the numerical analysis model of honeycomb plate cylindrical reticulated shell structure is reliable. In this paper, the seismic performance of the honeycomb plate cylindrical reticulated shell structure was investigated by modal analysis and time-procedure analysis. The results show that the low-order vibration modes of the cylindrical reticulated shell structure are generally dominated by lateral translational, plane torsional or vertical vibration. The natural frequency of cylindrical reticulated shell structure with bottom plate is greater than that of cylindrical reticulated shell structure without bottom plate, which has more reasonable mass, stiffness distribution. The cylindrical reticulated shell structure with bottom plate has better seismic performance, and its deformation under rare earthquake meets the specification requirements.
2 citations
TL;DR: In this article , a single-layer aluminum alloy cylindrical reticulated shell model with a length and width of 3.6 m is designed to study its seismic performance, and a shaking table test is carried out to test the natural vibration characteristics of the model.
Abstract: Aluminum alloys have been increasingly used in reticulated shells due to their favorable properties. A single-layer aluminum alloy cylindrical reticulated shell model with a length and width of 3.6 m is designed to study its seismic performance. A shaking table test is carried out to test the natural vibration characteristics of the model. A dynamic response test of the reticulated shell model is conducted under frequent, rare and severe earthquakes. The difference in the stress characteristics of the reticulated shell affected by two horizontal seismic waves is compared. The acceleration, displacement, and strain responses of the model under different horizontal seismic waves are analyzed, and the collapse and failure characteristics of the reticulated shell model are studied. The non-linear code ABAQUS is used for numerical simulation, and the validity of the finite element (FE) model is verified by comparing the simulation and experimental results. The results show that the bending moment controls the stress of the cylindrical reticulated shell members under a horizontal earthquake. Under rare earthquakes, the reticulated shell model remains elastic. After reaching the plastic stage under a severe earthquake, the reticulated shell retains its high bearing capacity, indicating excellent seismic performance. The joints of the reticulated shell exhibit weakness under stress, thus, it should be considered in the seismic design. The test results show that the single-layer cylindrical reticulated shell has the risk of progressive collapse.
1 citations
TL;DR: In this article , two Euplectella aspergillum-inspired 2D lattice structures were derived using Castigliano's second theorem, where plate-like elements were considered Euler beams, subjected to stretching and bending deformations.
Abstract: This study develops new analytical models for the two Euplectella aspergillum inspired 2D lattice structures. The analytical models for normal modulus and Poisson’s ratio are derived using Castigliano’s second theorem, where plate-like elements were considered Euler beams, subjected to stretching and bending deformations. The derived equations show the dependence of elastic properties on design and base material properties. The in-plane elastic properties are also simulated using finite element modelling (FEM). Furthermore, the theoretical parametric analysis is also carried out to investigate the effect of design variables on the elastic constants. Lastly, the modeled lattice structures are fabricated using the fused filament fabrication (FFF) process and used to validate the analytical and finite element results experimentally. The developed analytical models show good agreement with FEM and experimental results for effective modulus and Poisson’s ratio. The bio-inspired structures showed a wide range of elastic properties and suggested their applications in energy absorption and lightweight structure designs.
1 citations
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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
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
TL;DR: In this article, the continuous strength method (CSM) is extended to cover the design of non-slender and slender structural steel, stainless steel and aluminium hollow sections, underpinned by and validated against stub column and bending test results.
Abstract: Circular hollow sections (CHS) are widely used in a range of structural engineering applications. Their design is covered by all major design codes, which currently use elastic, perfectly-plastic material models and cross-section classification to determine cross-secti\on compressive and flexural resistances. Experimental data for stocky sections show that this can result in overly conservative estimates of cross-section capacity. The continuous strength method (CSM) has been developed to reflect better the observed behaviour of structural sections of different metallic materials. The method is deformation based and allows for the rational exploitation of strain hardening. In this paper, the CSM is extended to cover the design of non-slender and slender structural steel, stainless steel and aluminium CHS, underpinned by and validated against 342 stub column and bending test results. Comparisons with the test results show that, overall, the CSM on average offers more accurate and less scattered predictions of axial and flexural capacities than existing design methods.
124 citations
TL;DR: In spite of the spectacular development of reticulated shells, at least one problem has not yet been solved satisfactorily and that is the problem of buckling as mentioned in this paper, the instability of isolated members is st...
Abstract: In spite of spectacular development of reticulated shells, at least one problem has not yet been solved satisfactorily and that is the problem of buckling. The instability of isolated members is st...
112 citations
TL;DR: In this article, the fundamental approaches and main procedures adopted in the seismic design of steel frames, with emphasis on the provisions of Eurocode 8, are assessed and several issues that can lead to unintentional departure from performance objectives or to impractical solutions are identified and a number of clarifications and modifications suggested.
Abstract: This paper assesses the fundamental approaches and main procedures adopted in the seismic design of steel frames, with emphasis on the provisions of Eurocode 8. The study covers moment-resisting as well as concentrically-braced frame configurations. Code requirements in terms of design concepts, behaviour factors, ductility considerations and capacity design verifications, are examined. The rationality and clarity of the design principles employed in Eurocode 8, especially those related to the explicit definitions of dissipative and non dissipative zones and associated capacity design criteria, are highlighted. Various requirements that differ notably from the provisions of other seismic codes are also pointed out. More importantly, several issues that can lead to unintentional departure from performance objectives or to impractical solutions, as a consequence of inherent assumptions or possible misinterpretations, are identified and a number of clarifications and modifications suggested. In particular, it is shown that the implications of stability and drift requirements as well as some capacity design checks in moment frames, together with the treatment of post-buckling response and the distribution of inelastic demand in braced frames, are areas that merit careful consideration within the design process.
105 citations