Single-layer Latticed Domes Research Articles

Wind-induced dynamic response and its load estimation for structural frames of single-layer latticed domes with long spans

The main purpose of this study is to discuss the design wind loads for the structural frames of single-layer latticed domes with long spans. First, wind pressures are measured simultaneously at many points on dome models in a wind tunnel. Then, the dynamic response of several models is analyzed in the time domain, using the pressure data obtained from the wind tunnel experiment. The nodal displacements and the resultant member stresses are computed at each time step. The results indicate that the dome`s dynamic response is generally dominated by such vibration modes that contribute to the static response significantly. Furthermore, the dynamic response is found to be almost quasi-static. Then, a series of quasi-static analyses, in which the inertia and damping terms are neglected, is made for a wide range of the dome`s geometry. Based on the results, a discussion is made of the design wind load. It is found that a gust effect factor approach can be used for the load estimation. Finally, an empirical formula for the gust effect factor and a simple model of the pressure coefficient distribution are provided.

中間荷重を受ける単層ラチスドームの座屈荷重の推定法に関する研究

The present paper studies the effects of the intermediate loads along members on the ultimate strength, that is, elasto-plastic buckling strength of single layer lattice domes and proposes an effective method to evaluate the buckling strength based on column buckling strength for members which is used to size the member sections. The method is based fundamentally on a concept of column buckling strength in terms of generalized slenderness that includes the effects of shell-like buckling with nonlinear effects before ultimate loads. The results presented in the paper confirm that the proposed method works well for the estimation.

Wind-induced dynamic behavior and its load estimation of a single-layer latticed dome with a long span

This paper describes the results of some basic investigations on the wind-induced dynamic behavior and the resultant load estimation of a single-layer latticed dome with a long span. The wind pressures at many locations on dome models were measured simultaneously in a wind tunnel. The dynamic response of several dome models was analyzed in the time domain by using a finite element method. For generating a time history of the wind load vector, which consisted of concentrated loads at all internal nodes, the proper orthogonal decomposition (POD) technique was applied to the wind pressure data obtained from the wind tunnel experiment. The nodal displacements and the resultant member stresses, both axial and bending, were computed at each time step. Based on the results, the characteristics of the wind-induced dynamic response of the dome are discussed. In the analysis, special attention is paid to the vibration modes that dominate the dynamic response. Furthermore, a brief discussion is made of the load estimation for the dome. A simple model for estimating the design wind load, expressed as an effective load, is proposed.

Imperfection-Sensitive Overall Buckling of Single-Layer Lattice Domes

In this paper, the effects of geometric imperfections on the nonlinear buckling behavior of rigidly jointed single-layer lattice domes under vertical loading have been studied. A commercially available finite-element code has been used. Numerical experiments using varying levels of imperfection, chosen to be of the same forms as various linear buckling eigenmodes, have demonstrated the complexity of the buckling behavior. Lower bounds to the imperfection sensitivity of elastic overall buckling loads have been shown to result from the reduced stiffness analysis which is a simple extension to the classical linear buckling analysis. In addition an alternative elastic and plastic interaction empirical formula based upon the reduced stiffness loads has been seen to predict the lower bounds in the relatively large level of geometric imperfections.

大規模スペースフレームの動的解析に対するPCクラスタによる並列化システムの開発 : その1 改良した反復解法による並列化動的解析手法の効果について

In recent years, large-scale numerical analysis in structural design are increasingly demanded because of the necessity of realizing dynamic response analysis with elastic plastic behaviors in large-scale space frame structures. In order to realize large-scale numerical analysis, the developments of new high performance computing system without super-computers are desired. In several approaches, a parallel computing system is especially gathering the most attention for engineers. Thus the purpose of this study is to develop a parallel processing system for the dynamic analysis by using a PC cluster, which is a group of personal computers connected to a network mutually. Furthermore the calculating ability of the system is investigated by the numerical experiments for single layer lattice domes in this paper. It is demonstrated that the iteration method proposed to the dynamic analysis for structures is suitable for parallel calculations. Accordingly it was found through numerical experiments that the ability of parallel computing in this system produce good results and that parallel calculations using PC cluster with four personal computers reduce total analysis times to about 54% for models with different number of freedoms.

部材に分布荷重が作用するラチス構造の弾性座屈挙動

While the possibility of large space structural systems is pursued, it is important to study a new structural system as well as a new performance of materials. One of possible structural systems that have been developed is the hybrid system combining a space frame structure with a cladding, for example, a concrete slab, steel panels or membrane. In this case, constituent members of the structure are subjected to laterally distributed load due to the dead and live load. Then in this paper, the elastic buckling behavior of latticed structures is theoretically investigated on the condition that constituent members are subjected to laterally distributed load by using the proposed tangent stiffness equations of beam-column members. The treated latticed structures are double-layer latticed grids, cylindrical latticed shells and single-layer latticed domes.

Application of Scissors Type Deployabe System to Single-layer Latticed Dome

Application of Scissors Type Deployabe System to Single-layer Latticed Dome

Long-Span Lattice Roof for the Nagoya Dome

The Nagoya Dome is a multi-purpose stadium that can accommodate 40,500 spectators for a baseball game. Its steel roof has a hermetic quality with excellent sound insulating performance, since the dome is adjacent to a residential neighbourhood. A single-layer steel lattice dome has been adopted for the roof structure, both to minimize shadow effects from sunlight and to achieve the required ceiling height of at least 60 m for baseball. The roof has a span of 187.2 m, which makes it one of the largest single-layer lattice dome structures in the world. The roof area is approximately 29,000 m² with a glass skylight at the center occupying about 5,000 m². A retractable screen beneath the skylight controls the transmission of sunlight into the dome.

Wave Propagation Behaviour of Spatial Structures: Impact Response Analysis of Single Layer Lattice Domes

Many researchers have investigated the wave propagation behaviors of continuum spatial structures such as plate and cylindrical shell. But due to the numerical difficulty, there is very little research related to discrete spatial structures. The objective of this paper is to examine wave propagation behavior of single layer lattice domes subject to vertical impact load at the centre node. In the first part, an analytical method based on the Fourier transform and a matrix method is presented. In the second part, an impacted two dimensional lattice beam is analyzed in order to estimate the validity of the analytical program. In the last part, nine types of single layer lattice domes are analyzed to estimate the effect of member distribution density, member arrangement pattern and the jointing system, etc., upon the wave propagation behavior.

Wind loads and wind-induced dynamic behavior of a single-layer latticed dome

This paper describes the results of some basic investigations on wind loads and wind-induced dynamic behavior of a rigidly jointed single-layer latticed dome with a long span. First, the wind pressures were measured simultaneously at many points on a dome model in a turbulent boundary layer which simulated the natural wind over typical urban terrain. In the wind tunnel experiments, nine models with different rise/span and wall-height/span ratios were tested. In order to investigate the structure of the pressure field on the dome, the proper orthogonal decomposition (POD) technique was applied to the pressure data. The effect of dome geometry on the structure of the pressure field is briefly discussed. Then, the dynamic response of nine latticed domes with a span of 120 m was analyzed in the time domain. The equation of motion for the structural frame of the dome was numerically integrated by using the Newmark's β method; the wind loads, expressed as the concentrated loads at the interior nodes of the network, were generated by superimposing the first eight eigenfunctions of pressure, which were obtained from the above mentioned POD analysis. The results indicate that the dynamic response is dominated by several vibration modes; that is, the first three or four axisymmetric modes and a few lower asymmetric modes with small wave numbers both in the circumferential and in the radial direction.

集中荷重と分布荷重を受ける剛接合単層ラチスドームの変形特性に関する実験的・理論的研究

The deflection behavior of rigidly jointed single-layer latticed domes with several triangular networks subjected to a vertical concentrated load and/or uniform pressure have been studied experimentally. On comparing of the experimental results with calculated ones of finite element method, close agreements between them were obtained. The results indicate that the dome tends to buckle more easily as the distributed load increases and that the buckling characteristics depend on the Shell-likeness Factor S. In applying a concentrated load to the apex of the dome, the deflection characteristics standardize those for the other junctions.

Complete Load-Deflection Response and Initial Imperfection Analysis of Single-Layer Lattice Dome

The whole process of load-deflection response is analyzed for two single-layer lattice dome of big size as practical examples. The nonlinear behaviours of the perfect domes and their deflection shapes at several points after buckling are at first investigated. Two methods for imperfection analysis are then suggested. It is proved that single-layer lattice dome is very sensitive to initial imperfections and the suggested methods can be applied to real analysis.

単層ラチスドームの形状初期不整の推定手法について

Initial imperfections caused by random member length errors are discussed to investigate how the impferfections appear over an entire surface of a single-layer latticed dome and what magnitude of forces is induced in constituent members. The method to evaluate the imperfections is based both on a matrix analysis and a Monte Carlo technique taken into account of some degree of joint looseness. The present procedure and the results from the numerical analysis will provide practical and effective informations when designers face to estimating the quantities of imperfections in a latticed dome at a design stage.