Single-layer Reticulated Shell Structure Research Articles

Crashworthiness of AAG joints with a foam aluminum layer gusset plate

The gusset joint is the most widely used joint system in an aluminum alloy single-layer reticulated shell structure; it plays a vital role in the spatial grid structure. In this paper, the effects of different thicknesses of aluminum alloy gusset plates on the dynamic response and failure modes of aluminum alloy gusset (AAG) joints were studied by impact tests of three specimens. The test results show that the failure modes of AAG joints are a slight depression of the gusset plate, the local buckling of members, the local distortional buckling of members, and tearing of the lower flange and a web of members. The AAG joint inclines along the direction of the failed member and collapses. The finite element model of the AAG joint was established using ANSYS software. The stress, displacement, and deformation modes in the test and numerical simulation results were compared and analyzed, and the rationality of the numerical simulation results was verified. Based on the failure mode of the specimens, a design method for improving the impact resistance of AAG joints with aluminum foam layer gusset plate (AFLGP) is proposed. The numerical simulation results show that an AAG joint with an AFLGP effectively reduces the maximum peak value of impact loads through the deformation of the aluminum foam. In the elastic and elastic-plastic stages, AAG joint with AFLGP had better impact resistance, and the energy absorbed by its rods was 25.44% ∼ 30.36% lower than that of AAG joints alone. Finally, the influence of the thickness of the AFLGP on the impact force and energy absorption of the AAG joint was studied. The aluminum foam gusset layer plate is approximately twice as thick as the aluminum alloy gusset plate had the best protection effect on the AAG joint.

Buckling of single-layer reticulated shell structures with corroded welded hollow spherical joints based on multi-scaled model

Buckling of single-layer reticulated shell structures with corroded welded hollow spherical joints based on multi-scaled model

Dynamic stability of single-layer spherical reticulated shell structures under earthquake action

In past decade, earthquake disasters have seriously damaged nonstructural components, so it is very important to study their dynamic stability. However, the existing researches mainly focus on the dynamic stability of multistory and high-rise buildings, and there are still deficiencies in the analysis of dynamic stability of reticulated shell structures under earthquake action. This paper takes the 40 m span K8 single-layer spherical reticulated shell structure with practical engineering significance as the research object, we study its dynamic instability characteristics under earthquake action, and propose a dynamic stability judgment method. The influence of various parameters on the critical loads of emotional stability of reticulated shell structures is systematically analyzed, including the impact of horizontal seismic action, the vertical seismic activity, and the three-dimensional seismic movement, considering the influence of material elastoplasticity; the result of different seismic inputs, the effects of initial geometric imperfections; the effects of varying rise span-ratio. In this paper, to investigate the nonlinear time-history response analysis, we uses the finite-element package ABAQUS. We first analyze the rise-span ratio as the dynamic stability of 1/3 single-layer reticulated shell structure under the action of the El Centro (1940) earthquake to reveal the dynamic loss of reticulated shell structure under earthquake action stable feature. The practical method for determining the proposed dynamic stability has a clear physical meaning and a range of applications. Our findings highlight that the critical load for dynamic stability under horizontal earthquake action is significantly lower than vertical earthquake action, and the critical load is the lowest under three-dimensional earthquake action. Material elastoplasticity influences the critical loads for dynamic stability of reticulated shell structures under different ground motions. The critical load of dynamic stability of single-layer structures with a larger rise-span ratio is lower, while those with a smaller one is higher. The initial geometric defects of the structure should be considered in practical engineering applications. The reticulated shell structure with a larger rise-span ratio needs to consider the dynamic stability problem in the strong earthquake area.

The effect of edge valency on the load resistance of single-layer reticulated cylindrical shells

The arrangement of members plays a crucial role in determining the resistance of reticulated cylindrical shells, in addition to rise-to-span ratio, cross-section of the members, rigidity of the joints, and support conditions. Although studies on the comparison of shell structures with different configurations were available, the effect of the member arrangement on the performance of reticulated shell structures based on valency of elements was never investigated before. This paper investigates the effect of edge valency on the load resistance of shell structures by studying the behaviour of four cylindrical shell configurations with different edge valencies of vertices and faces. The limit load of the shell structures—with different span-to-rise ratios, length-to-span ratios, support conditions, load patterns, and different magnitudes of initial geometric imperfection—was calculated based on geometrical and material non-linear analyses. The results show that the increase in the edge valency of the vertices increases the overall resistance of single-layer reticulated cylindrical shells with all edges supported. In addition to edge valency, member orientation plays a prominent role in determining the overall resistance of single-layer reticulated shell structures with longitudinal edges supported. The findings on edge valency will help the designer to rearrange the members within a structure without compromising the overall resistance, resulting in an economical design.

Stability of single-layer reticulated shells with AAG joints

Due to the advantages of light weight, high strength and corrosion resistance, aluminum alloys have been widely used in large-span space structures, and the application form is mainly single-layer reticulated shells.Considering the non-negligible stability problems of single-layer reticulated shells, this paper starts the stability research with the idea of ”member to structure”. By establishing refined numerical models of single-layer reticulated shell with aluminum alloy gusset (AAG) joints, the effective length factor of members and the overall structural stability considering the failure of the gusset joints are carried out. The main conclusions are as follows:(1) The in-plane and out-of-plane effective length factor of members of the aluminum alloy single-layer reticulated shell with gusset joints are recommended to be 1.0 and 1.9 respectively;(2) The stable bearing capacity ratio of rigid reticulated shell, semi-rigid shell, and semi-rigid reticulated shell considering joint failure is about 1:0.9:0.72. The research results of this paper provide a basis for the stable design and specification of aluminum alloy single-layer reticulated shell structures.

Method for considering corroded joints in buckling analysis of single-layer reticulated shell structures

In this paper, an efficient numerical algorithm for considering the corroded joints is originally proposed. This method is utilized to estimate the buckling factor of single-layer reticulated shell structures (SLRSS) connected by welded hollow spherical joints (WHSJs) which is commonly used in reticulated shell structures. WHSJs in actual projects are subjected to corrosion with various severities since they have been utilized 50 years ago. The existing literature mainly focused on the mechanical behavior of WHSJs, and the influence of corroded WHSJs on structural buckling capacity is seldom studied due to the lack of efficient numerical algorithm. In the present study, a numerical method considering the degradation of connection is proposed to investigate the buckling capacity of single-layer reticulated shell. The randomness of bending (axial) stiffness is achieved by double element. The influences of bending and axial stiffness and their capacities are revealed. A probabilistic distribution model of buckling capacity is proposed by performing stochastic numerical analysis. The main contribution of this work is proposing the efficient numerical model for considering degraded connection. The conclusions derived in this study can provide reference for the safety estimation of SLRSS.

Influence of welding deformation on anti-collapse performance of single-layer reticulated shell structures with prestressed cables

In this paper, the ABAQUS finite element software is used to model and analyze the single-layer reticulated shell structure. And the method of removing the constraints of key components is used to analyze the anti-continuous collapse performance of this reticulated shell structure under the action of geometric defects and welding deformation. Welding deformation is mainly caused by welding and prestressed cable tensioning of single-layer reticulated shell. The results show that the removal of the key columns under the reticulated shell will lead to the continuous collapse of the upper part, which leads to the continuous collapse of the whole structure, and the welding deformation can make the continuous collapse of the whole reticulated shell more obvious. Thus determining the influence of geometric defects and temperature shrinkage deformation on the anti-continuous collapse performance.

A Spiral Single-Layer Reticulated Shell Structure: Imperfection and Damage Tolerance Analysis and Stability Capacity Formulation for Conceptual Design

Single-layer reticulated shell structures are widely used, but their stability performance is not ideal. Moreover, they are sensitive to structural damage and imperfections, while the existing conventional design methods of increasing the cross-section, strengthening corrosion protection, and densifying the structural grid are not economical. This study employs a modified and bionic structure—a spiral single-layer reticulated shell structure—to solve the problem. First of all, according to the current Chinese design codes, its mathematical model and geometric model are designed. Then, its damage and imperfection tolerances are analyzed and compared with a traditional single-layer reticulated shell. We then propose a universal bearing capacity formula. Our research conclusions prove that the spiral single-layer reticulated shell structure has a higher tolerance to damage and imperfections while maintaining stability. Moreover, the precise bearing capacity formula proposed will help engineers to efficiently select the structure configurations in the conceptual design phase. Therefore, the spiral single-layer reticulated shell structure is worthy of popularization and application in engineering practice.

Study on progressive collapse resistance of single-layer reticulated shells

In order to analyze the progressive collapse resistance of single-layer reticulated shells, the finite element model of single-layer reticulated shell structure was established by ABAQUS software, and the method of removing key component constraints was used to simulate the progressive collapse resistance of the single-layer reticulated shell structure. The results show that the removal of the key components can cause the continuous failure of the upper members of the reticulated shell, and then lead to the progressive collapse of the whole structure.

Parametric modeling program of single-layer spherical reticulated shell structure and prediction program of global stability ultimate bearing capacity

In this paper, the “battery” program was compiled based on the parametric tool Rhino+Grasshopper and the parameterized modeling function of K-type single-layer spherical reticulated shell structure was realized. At the same time, based on BP neural network algorithm and considering the complex mapping relationship in nonlinear analysis, a neural network model and program was established to predict the ultimate bearing capacity of K8 single-layer spherical reticulated shell structure. The results show that the program can realize the modeling process efficiently and the reliability of the neural network to predict the ultimate bearing capacity of single-layer reticulated shells is verified, which provides an effective tool for improving the parametric modeling and structural optimization of single-layer reticulated shell structure.

Probabilistic seismic analysis of single-layer reticulated shell structures controlled by viscoelastic dampers with an effective placement

In this paper, an effective placement of viscoelastic dampers on single-layer reticulated shell structures is proposed to mitigate seismic response. For comparison, an existing placement of viscoelastic dampers is also investigated. The effectiveness of the proposed placement of viscoelastic dampers is investigated from both deterministic and probabilistic perspectives. The single-layer reticulated shell structure is driven by the stochastic seismic ground motions, which are modeled via the random function based spectral representation method. The probability density evolution method is then implemented for probabilistic response and reliability analyses of the shell structure. A series of deterministic numerical simulations are first implemented under different earthquake excitations, including both actual and artificial seismic ground motions, to compare the control effects in deterministic sense. Then, the control effects of the proposed placement and the existing placement are compared in probabilistic sense, where the probabilistic responses, equivalent extreme value distributions and failure probabilities are extracted. Numerical results demonstrate that the seismic performance of the shell structure can be greatly improved by arranging the viscoelastic dampers with the proposed placement.

Hysteretic behavior of bolt–column joints under in-plane loading combinations by experimental and numerical study

The bolt–column (BC) joint has enough bending stiffness satisfying large-span single-layer reticulated shell structure well. The hysteretic behavior of BC joints under different in-plane combinations of bending moment and axial force is investigated in this study. Firstly, precise finite element models (FEM) of the BC joints, which considered the material and the geometric and contact nonlinearities, were established in ABAQUS. The failure modes, hysteretic curves, skeleton curves, and bearing capacity for assessing the joint hysteretic behavior were investigated in detail by the numerical analysis. BC joints under different combined axial force and cyclic bending loads were studied by numerical analysis to obtain the impact of the axial force, which provides necessary technical support for engineering practice. Three tests were conducted and the results verified that the FEM was effective in simulating the joint behavior by comparison with the test results. The research shows that the hysteretic capacity of BC joints under in-plane bending is weaker than that under out-of-plane bending, but the bearing capacity of former is higher. Increasing the thickness of the side and middle plates can slightly enhance the joint in-plane hysteretic capacity, which is improved with small axial compression and reduced with high axial compression and axial tension.

Dynamic Response Analysis and Model Test Research on K6 Single-Layer Spherical Reticulated Shells Subjected to Impact Load

To study the dynamic response characteristics and failure process of single-layer spherical reticulated shells under impact loads at different loading points, impact dynamic analysis and experimental study are conducted on the K6 single-layer reticulated shell structure. First, the basic theory of numerical calculation and the model parameters are described. Then, dynamic response analysis under impact load is done by choosing different impact points. Finally, the impact test is performed on a large-scale shell model, dynamic response data of key members and nodes of shell structure are obtained, and the shell deformation and destruction process is recorded by a high-speed camera. The results show that the structural dynamic response gradually increases farther from the base point under the same impact force. The nearer the impact point is, the earlier the response occurs, and the larger the corresponding amplitude will be. The apex is the most unfavorable impact loading point, and the member at the apex should be strengthened for impact resistant design of the reticulated shell. The transmission time of the impact dynamic response from the impact site to the entire reticulated shell is short.

Influence of welded hollow spherical joints on the mechanical behavior of single-layer reticulated shell structures

Welded hollow spherical joints (WHSJ) are widely used in space lattice structures. Beam models are widely adopted in analyzing integral structures for high computational efficiency. However, the influence of WHSJ cannot be estimated accurately, and few studies on the accuracy of beam models are available. Numerical models in different scales were established, and results derived from different models were compared to investigate their accuracy. Results indicated that the influence of WHSJ on the mechanical behavior of integral structures varies along with its scale. A large error may exist in the results obtained by the beam models, especially for the models with thick pipe and thin WHSJ. The largest error in ultimate strength is 250% when components were meshed into one beam element, and the minimum error of results derived from the beam model is approximately 10% when components were meshed by a sufficient number of elements. Results derived from multi-scaled models agree well with the results derived from the refined model.

Experimental investigation on bending and shear performance of two-way aluminum alloy gusset joints

Two-way aluminum alloy gusset joints (AAGJs) are considered to be employed in cable-stiffened aluminum alloy single-layer reticulated shell structures meshed with quadrilateral grids. In this study, a series of experiments on six AAGJs with and without shear connectors were conducted to investigate their semi-rigid behavior. Two joints were subjected to pure bending moments and others to shear loads, then their corresponding failure modes were investigated which were mainly beam rupture, beam web buckling, and bolt failure. The moment-rotation curves, shear load-rotation curves, and strain-load curves were also obtained, indicating that AAGJs are typical semi-rigid joints. Shear connectors can optimize the load transferring path and improve ductility under bending moment while enhancing shear performance significantly. A simplified theoretical AAGJ model was also established and parameterized according to the experimental results.

Dynamic Collapse Analysis of Single-Layer Lattice Domes with Supporting Frames

Dynamic collapse analysis is an important research subject for large span single layer reticulated shell structures. In this paper, the dynamic collapse behavior of the single layer reticulated shell with substructure which support the reticulated shell are investigated under the earthquake actions. In the analysis, the geometric imperfections, the material and the geometric nonlinear of the structures are considered. The effects of different stiffness of substructure to the collapse earthquake accelerations and the plastic member distribution of the reticulated shell are investigated.

Analysis on complex structure stability under different bar angle with BIM technology

Summary Sun Valley, the landmark building of World Expo in Shanghai, which has free surface with single-layer reticulated shell structure, is a typical complex structure. CAD/CAM integrated information system to design is used for the complex structure; however, it is a very rigorous process to be used widely. The relevant technology of the Sun Valley is not open to the public at present, so we try to use BIM technology to model the Sun Valley, including architecture modelling and structure analysis. By analysis of the Sun Valley structure using this method, it is proved that the problems in modelling may be solved by writing some script codes in Rhino software and the stability of the model can also be analyzed. The new approach is viable and effective in combination with different softwares such as Rhino, Revit, and Midas in solution of the complex shaped surfaces’ structure for modelling and calculation.

Thermal and integral lifting analysis of a lattice shell lighting roof based on genetic algorithm and probabilistic design

The optimum analysis for Railway Station Building of Yujiapu (a shell-shaped single-layer reticulated shell structure) was conducted based on genetic algorithm. An elitist genetic algorithm was used by combining Matlab and a general finite element software ANSYS. Analysis was firstly conducted to study the influence of temperature load on support reaction force, then the optimal combination of support stiffness to minimize the effects of temperature load was derived by using GA. Subsequently, probabilistic design analysis was conducted for the integral lifting process and the key lifting points which influence the stress of lifting zone significantly was derived, at the same time the probability distribution model of lifting height difference was established and validated. Finally, the same genetic algorithm was adopted to optimize the combination of lifting height difference, the maximum stress of lifting zone will be reduced obviously by using the computed results. The efficiency and applicability of GA in optimization of complex structures were demonstrated in this paper.

Elasto-Plastic Bearing Capacity of Four Types of Single-Layer Reticulated Shell Structures Under Fire Hazards

Single-layer reticulated shells are widely used in spatial structures. One critical factor that has to be considered in the design of reticulated shells is the significant adverse impact of high temperature caused by fire on the structures. In order to study the variation of elasto-plastic bearing capacity under high temperature by fire, four types of single-layer reticulated shells (i.e. K6, Geodesic, Schwedler and Lamella) are investigated under two typical fire conditions (i.e. global nonuniform temperature distribution and local high temperature) by the geometrically and materially nonlinear analysis and statistical methods. Practical design formulae for calculating the elasto-plastic bearing capacity of reticulated shell structures under different fire conditions and ambient temperatures are proposed based on the numerical simulation results.

Application of Modified Consistent Mode Imperfection Method in Stability Analysis of Single-Layer Reticulated Shells

Based on the probability reliability theory, this paper proposes a modified consistent mode imperfection method, which fits the integral stability analysis of single-layer reticulated shells with the initial geometric imperfections. Nearly 1000 elasto-plastic load-deflection overall processes of four different rise-to-span ratio for Kiewitt-8 single-layer reticulated shells are analyzed by using the random imperfection mode method, the consistent mode imperfection method and the modified consistent mode imperfection method respectively. The study shows that the random imperfection mode method can assess the influence of initial geometric imperfections on structure stability more scientifically, but the calculation is quite large. By using the consistent mode imperfection method, the buckling load is not sure to be the most unfavorable, and the degree of reliability couldnt be ensured effectively. The modified consistent mode imperfection method can gain the buckling load which meets the requirement of probability reliability with less calculation. It can also assess the stability performance of single-layer reticulated shell structure more reasonably and safely.