Single-layer Lattice Shell Research Articles

Study on the Static Stability and the Ultimate Bearing Capacity of Vierendeel Latticed Shells

Studies on the static stability and the ultimate bearing capacity of vierendeel latticed shells have been carried out. The buckling modal and the whole course of instability are shown using the Finite Element Method. The ultimate bearing capacity is compared with that of the single-layer latticed shell structure. The results show that the ultimate bearing capacity of the vierendeel latticed shells is 2.87 times more than that of the single-layer lattice shell in the condition of consuming the same steel. The vierendeel latticed shell structure not only has the advantages of concision and transparency like the single layer latticed shell structure, but also has the stability and carrying capacity like double-layer latticed shell structure.

Dynamic Stability Analysis of K8 Single-Layer Latticed Shell Structures Suffered from Earthquakes

Aiming at the dynamic stability of the K8 single-layer latticed shell structures, it was carried out the dynamic stability analysis based on the finite element method(FEM) in this paper. The dynamic responses of the structure are calculated using the FEM and the B-R rule is applied to determine the dynamic instability critical loads. Results show that the dynamic instability is prone to take place in the K8 single-layer latticed shell structures under the severe seismic load and the dynamic instability critical seismic wave peak value is about 0.7g. The location of instability starts from the intersection between the third circular members and the radial members, then it spreads abroad until the structure collapses.

FEM Simulation and Field Monitoring of Depropping Procedure of a Large-Span Single-Layer Latticed Shell

This paper investigates the depropping procedure of a large span single-layer dome-shape latticed shell roof structure through numerical analysis and field measurements. The depropping procedure consists of six steps. For each step, the joint displacements and member internal forces of the roof structure were first predicated using a numerical model. Based on the simulations results, instruments as vibrating wire strain gauge, total station, accelerometer and global positioning system (GPS) were installed on the structure to monitor the actual displacements and variations of structural members' internal forces during the depropping procedure. The GPS data are compared with total station measurements to learn its applicability for monitoring depropping procedure of large roof structure. The comparison between the numerical results and field measurements demonstrates that the suggested simulation method is reasonable in the sense that the variation trend of deflection and internal forces of the structure can be captured. The GPS technology gives more accuracy measurements in horizontal displacement than vertical deformation. A combination of GPS technology and total station can increase the displacement measurement accuracy.

Damage Assessment of Single-Layer Cylindrical Latticed Shells Based on Degradation of Static Stability Capacity

The static stability capacity is the main index to measure the whole mechanical performance of single-layer latticed shells. Three single-layer cylindrical latticed shells with different height to span ratio were modeled, and their seismic damage were assessed by the degradation of static stability capacity incurred by earthquakes. Two different static load patterns were considered: dead load and the combination of dead load and half span live load. The results show that the damage assessment method is applicable to single-layer cylindrical latticed shells, and the static load patterns have no big influence on the damage assessment of the single-layer cylindrical latticed shells.

Scale Model Test Research on Cable Supported Barrel Vault Structure

By setting cables and struts in place in the single-layer cylindrical latticed shell, a new-style prestressed spatial steel structure--cable supported barrel vault structure is constructed, the static load test research on which is carried out for the first time in this paper. Based on the prototype building, a scale model with the scale of 1:15 is designed and manufactured for the test. The research results indicate, the static behavior of the prototype structure can be reflected approximately by this scale model. The static behavior of the single-layer cylindrical latticed shell is improved significantly by adding cables and struts, i.e., the cable supported barrel vault structure is a kind of highly efficient prestressed spatial steel structure. Compared with the case of full-span load, the half-span load makes the cable supported barrel vault structure unsafer.

Study on Stability of a New Prestressed SINGLE-Layar Spherical Lattice Shell

Prestressing of lattice shell is realized by cable, and author put forward a new kind of layout: The prestressing has been brought to bear by hoop and radial element of single-layer lattice shell, which avoid cable's effect on architectural purpose. The element has been made to sleeve, and the magnitude of prestressing is dominated by bolt. Article shows an example of K6, K8 single-layer spherical lattice shell, and the prestressing have been exert on partial ribs and hoops. The prestressing has been calculated by element axial force under normal loading. Stability of shells have been studied, and show the deformation satisfy the criteria under normal loading; The ultimate capacity has been improved obviously, loads transfer is rational. The new layout of prestressing is a promising technique.

Seismic isolation analysis of FPS bearings in spatial lattice shell structures

A theoretical model of a friction pendulum system (FPS) is introduced to examine its application for the seismic isolation of spatial lattice shell structures. An equation of motion of the lattice shell with FPS bearings is developed. Then, seismic isolation studies are performed for both double-layer and single-layer lattice shell structures under different seismic input and design parameters of the FPS. The influence of frictional coefficients and radius of the FPS on seismic performance are discussed. Based on the study, some suggestions for seismic isolation design of lattice shells with FPS bearings are given and conclusions are made which could be helpful in the application of FPS.

Formation and stability of a cylindrical ILTDBS reticulated mega-structure braced with single-layer latticed membranous shell substructures

For a cylindrical intersecting-latticed-three-dimensional-beam-system (ILTDBS) reticulated mega-structure braced with single-layer latticed membranous shell substructures, the formation method, form parameters and support styles are first studied in this paper. And a program, which can automatically generate the form of the structure, is developed. Then the geometrically nonlinear mechanical model and stability analysis program are developed, and the stabilities of the structure are investigated. The structural ultimate bearing capacities and buckling modes including overall buckling and local buckling are studied in detail by parametric analyses. And the laws of determination of various parameters of the structure with different spans on the critical state between local and overall buckling are obtained. The work will provide guidance in theory for practical applications of this kind of structure.

Nonlinear dynamical bifurcation and chaotic motion of shallow conical lattice shell

The nonlinear dynamical equations of axle symmetry are established by the method of quasi-shells for three-dimensional shallow conical single-layer lattice shells. The compatible equations are given in geometrical nonlinear range. A nonlinear differential equation containing the second and the third order nonlinear items is derived under the boundary conditions of fixed and clamped edges by the method of Galerkin. The problem of bifurcation is discussed by solving the Floquet exponent. In order to study chaotic motion, the equations of free oscillation of a kind of nonlinear dynamics system are solved. Then an exact solution to nonlinear free oscillation of the shallow conical single-layer lattice shell is found as well. The critical conditions of chaotic motion are obtained by solving Melnikov functions, some phase planes are drawn by using digital simulation proving the existence of chaotic motion.

Dynamic characteristics of single-layer cylindrical lattice shells

This investigation is concerned with the free vibration and seismic response of single-layer cylindrical lattice shells. The effects of basic structural parameters such as the ratio of rise to span, mass, damping, the ratio of length to span and the rigidity of supports, on the dynamic behaviour of single-layer cylindrical lattice shells are investigated in detail. In this paper the finite-element method is used, in which three-dimensional beam elements are employed. Both the natural frequencies and their associated modes of vibration are obtained with a subspace iteration technique, and the direct dynamic analysis method is adopted to analyse the dynamic responses of single-layer lattice shells under vertical and horizontal earthquake excitations. The objective of this study is to achieve a better understanding of the dynamic characteristics and seismic behaviour of single-layer lattice shells. The results are valuable for the earthquake-resistant design of such structures.

Dynamic characteristics of single-layer cylindrical lattice shells

This investigation is concerned with the free vibration and seismic response of single-layer cylindrical lattice shells. The effects of basic structural parameters such as the ratio of rise to span, mass, damping, the ratio of length to span and the rigidity of supports, on the dynamic behaviour of single-layer cylindrical lattice shells are investigated in detail. In this paper the finite-element method is used, in which three-dimensional beam elements are employed. Both the natural frequencies and their associated modes of vibration are obtained with a subspace iteration technique, and the direct dynamic analysis method is adopted to analyse the dynamic responses of single-layer lattice shells under vertical and horizontal earthquake excitations. The objective of this study is to achieve a better understanding of the dynamic characteristics and seismic behaviour of single-layer lattice shells. The results are valuable for the earthquake-resistant design of such structures.

Dynamic behavior of single-layer latticed cylindrical shells subjected to seismic loading

The single-layer latticed cylindrical shell is one of the most widely adopted space-framed structures. In this paper, free vibration properties and dynamic response to horizontal and vertical seismic waves of single-layer latticed cylindrical shells are analyzed by the finite element method using ANSYS software. In the numerical study, where hundreds of cases were analyzed, the parameters considered included rise-span ratio, length-span ratio, surface load and member section size. Moreover, to better define the actual behavior of single-layer latticed shells, the study is focused on the dynamic stress response to both axial forces and bending moments. Based on the numerical results, the effects of the parameters considered on the stresses are discussed and a modified seismic force coefficient method is suggested. In addition, some advice based on these research results is presented to help in the future design of such structures.

New Structural Forms and New Technologies in the Development of Steel Space Structures in China

The last decades have seen major advances in the research, design and construction of steel space structures (space grid structures) in China. This paper provides a review of these developments, with particular attention to the new technologies and new structural forms employed in China. The following topics on new technologies and new structures are given emphasis: long-span and large-area grid structures; composite space trusses; composite reticulated shells; triple-layer space trusses; partial double-layer (single-layer) lattice shells; prestressed grid structures; cable-stayed grid structures; special grid structures; new types of joints; theoretical work and application research. Prospects for steel space structures in the 21st century are presented at the end of this paper.

パーツ方式によるハイブリッド単層ラチスシェル及び対座屈荷重設計法の提案

Single-layer lattice shells composed of identical units are light and have simple joints compared with double-layer lattice shells. Their bending stiffness, however, is low and then buckling sometimes becomes a serious problem. In order to improve this drawback, we propose a hybrid single-layer lattice shell combined with supplementary parts. In the paper, structural characteristics such as displacement distributions and buckling loads of EP single-layer lattice shells and hybrid single-layer lattice shells are presented. And, we suggest a design method to obtain higher buckling load of hybrid single-layer lattice shells.

アルミニウム単層トラスの構造挙動に関する実験的研究

One of the targets in the design of large-span structure is to minimize the weight. Based on this point, a new type of single-layer lattice shell consisted of aluminum members and joints has been developed and examined by authors since 1989. This single-layer lattice shell has insertion joint system which shows semi-rigid characteristic for the bending moment. In order to grasp the structural behaviours of the lattice shell, the following reseaches have been planed and performed : (1) Experiment of structural elements such as member and joint, (2) Experiment of small-scale models. In the first part, the tensile, compressive and bending tests for structural elements are shown in order to examine the stiffness and the ultimate strength. In the second part, the structural behaviour of four kinds of small-scale models with a diameter of 4.2 meters are examined under an uniform load and an concentrated load in the center part. For all models, torsional instability of node occurs because the bending rigidly in the in-plane direction is weaker. In the third part, exparimental results are presented and evaluated in detail.

Computation Models and Numerical Solution Procedures for Nonlinear Analysis of Single Layer Lattice Shells

Single-layer space frames consisting of reticulated surfaces with assumed pin or rigid jointed members are widely used in practice. This is accounted for by the fact that they meet the need to cover large spans without the use of intermediate supports, while at the same time, yielding a very small structural weight per unit of area covered. Because of the in-plane membrane action of shallow single-layer lattice shells associated with their initial curvature, such structures are able to carry considerable out-of-plane loads relative to the weight of the structure itself. However, in the case of shallow single-layer lattice shells with small rise-to-span ratios, the response is highly nonlinear even when the stresses in the members are small enough to ensure that the material properties fall within the elastic range. These structures become unstable at some critical value of the load and any design based on an elastic linearized analysis is potentially unsafe. Shallow single-layer lattice shells are characterized by a strong nonlinear behaviour with considerable softening, so they are extremely sensitive to out-of-plane instability and are affected by general and local instability. As far as the pre-buckling range is concerned, an extensive literature dealing with effective solver techniques exists for the numerical solutions of structural problems, but only a few algorithms have been put forth with a view to tracing the nonlinear response from the pre-limit range into the post-limit one. The main purpose of this paper is to review these methods and to discuss their performance. The author's ASEF-N computer program and selected numerical examples are presented.

Instability Problems in Space Structures

The paper presents the principal aspects of stability analysis of space structures. In describing the evolution of the principles of analysis, the author's method of stable and unstable components is also discussed. It is shown that spatiality has contradictory effects: on the one hand, it leads to an increase in the critical bifurcation load and on the other hand it increases the sensitivity to geometrical imperfections by increasing the unstable components. The principal aspects of the stability analysis of structures whose spatiality is due to their shape (shells, double-layer grids or single-layer latticed shells) are described and a number of previous unsatisfactory solutions are discussed. In structures whose spatiality is due to interaction, the stability check is at present not quite correct, but because of bending moments it does not differ very much from a more accurate analysis.