Rise-span Ratio Research Articles

Strength assessment of curved steel-concrete-steel sandwich shells with bolt connectors under concentrated load

In this study, experimental works on four curved steel-concrete-steel (C-SCS) sandwich shells were carried out to assess their behaviors when subjected to concentrated loading with a 100-mm diameter hemispherical steel hammer through analyzing the failure mode, load–displacement relationship, strain, and deformation. The influences of the concrete and steel plate thicknesses, shear connector spacing, and rise–span ratio were numerically investigated. The results showed that the ultimate strength of C-SCS shells was improved with increasing concrete and face steel plate thicknesses and with decreasing shear connector spacing. The optimal rise-span ratio was found to be between 0.25 and 0.33. Moreover, to predict the nominal yield strength and the ultimate strength of C-SCS shells, an analytical model was developed, which matched well with the experimental and FE results. This analytical model can be used as a quick method to calculate the resistances of C-SCS shells under concentrated loading by a hemispherical steel hammer.

The effect of rise-span ratio on the rigid-framed arch bridges

The rigid-framed arch structure is a popular bridge structure on medium and small span bridge such as flyover. Rise-span ratio affects the rigid-framed arch structure performance, in order to analyse the influence on the rigid-framed arch structure of different rise-span ratio, a calculation model of the rigid-framed arch structure on the basis of the project established using the large general finite element software, by adjusting the rise value to change the rise-span ratio, analysing and comparing the structural internal force and deformation condition of the rigid-framed arch in different rise-span ratio under the action of constant live load, temperature change, and foundation settlement. The influence of different rise-span ratio on the rigid-framed arch stress summarized.

Parametric static analysis of a new type of fabricated plate grillard thin shell roof structure

The new fabricated slab ribbed shell roof structure is a new structure based on a large-span steel-concrete composite thin shell roof. An assembly unit composed of a thin-walled steel ribbed plate, a base plate, and concrete provided with bolt holes, and a plate-grid thin shell roof structure formed by the assembling and connecting assembly units. Considering the influence of the structure’s rise span ratio, five groups of rise span ratios were used for finite element analysis and compared with single-layer cylindrical reticulated shells. The analysis shows that the mean value of the ultimate load of the new prefabricated panel latticed thin shell roof structure is increased by 5.3% on average compared with the single-layer cylindrical reticulated shell structure. When the rise span ratio is 1/5, the structure has the largest stiffness and the smallest deformation; when the rise span ratio exceeds 1/5, the growth trend in the ultimate load that the structure can withstand will become smoother, and the average maximum displacement will decrease by 4.3% compared with the single-layer cylindrical reticulated shell, which shows that the grid lattice structure has better stiffness.

Vertical earthquake vulnerability of long-span spherical lattice shells with low rise-span ratios

This paper presents an approach for quickly predicting vulnerable areas of long-span spherical lattice shells under vertical earthquakes using the equivalent continuum analogy. According to the moment theory from classical shell mechanics, the equations for locating the position of maximum nodal displacement are deduced in the elastic range, while considering the heterogeneity in equivalent stiffness. Based on the plastic limit analysis theory, a defined relative stiffness index is proposed by integrating the curvature variation over the corresponding node-bearing area to predict the position of maximum nodal displacement in the plastic range. Several spherical single-layer lattice shells are analyzed using the finite element method to verify the proposed method, and the relative stiffness index, which could be used as an indicator to validate and adjust structural design configurations. As a large-span shell is expected to perform better when each ring has a similar equivalent stiffness index, thereby avoiding abrupt changes in stiffness. The case study indicates that the vulnerable area in such a long-span single-layer lattice shell can be predicted and controlled based on the relative stiffness index values. Additionally, the desired seismic damage-endurance capacity can be obtained by adjusting the relative stiffness index of each ring to ensure that the structure is sufficiently resilient. The method for predicting displacement-based vulnerable areas using the equivalent continuum analogy provides a practical tool for a quick assessment of preliminary design schemes of new lattice shells and can be also applicable to existing and ready-for-retrofit lattice shells.

A theoretical and experimental study on in-plane buckling of orthotropic composite arches under an arbitrary radial point load

Nonlinear in-plane buckling behavior of fixed orthotropic composite arches under an arbitrary radial point load is investigated theoretically, numerically and experimentally in this paper. Analytical solutions that include the bending-stretching coupling effect are developed for both critical buckling load and nonlinear equilibrium path and are validated by the finite element model. A variable-speed displacement control loading system with automatic loading direction adjustment is designed and set up for the test to record the complete buckling evolution process. Comprehensive analytical and experimental results for the critical buckling load and nonlinear equilibrium path of the arches are presented in both tabular and graphical forms, followed by a parametric study with a particular focus on the influences of loading position, stacking sequence as well as the rise-span ratio on the buckling load. Research results indicate that the buckling mode of the composite arch is highly dependent on the modified slenderness ratio. Both buckling mode and the switching modified slenderness ratio are significantly influenced by the loading position. The buckling load is also highly sensitive to stacking sequence and decreases as the 90° lamina is placed far away from the mid-plane.

On the static properties and stability of 800 m long-span mega-latticed suspension structures

In order to develop super long-span structures, the characteristics of suspension bridges are considered for use in suspended hybrid structures, initially considering a structure with a span of 800 m. The control parameters for the geometrical shape of the structure are given, and a structural model is established using ANSYS. The initial form of the main cable is studied and a feasible pylon scheme is designed. Static, stability and parameter analysis of the structure are conducted, and progressive collapse analysis after the breakage of the sling is undertaken. The results show that both wind loads and temperature have significant effects on the structure. There is not a destabilization problem exist in the structure and stiffness should be taken as the main consideration. The influence of geometrical parameters on the mechanical properties of the structure is studied, and variation rules for the parameters are summarized. The rise-span ratio of has a great influence on structural performance. When it changes from 1/10 to 1/5, the displacement decreases by 43%, the steel consumption reduces by 8.86%, and the stress decreases by about 10.69%. The possible progressive collapse of the structure following the failure of a single sling is examined. Using transient dynamic analysis. The time history curves of the responses to the process of the breakage of the sling are given. The work shows that it should be possible to develop suspended mega-latticed structures with spans of 800 m.

Damage mechanism of giant orthogonal grid barrel vault under strong earthquake

PurposeGiant orthogonal grid barrel vault is generated by deleting members in the inessential force transfer path of the two-layer lattice barrel vault. Consisting of members in the essential transfer path only, giant orthogonal grid barrel vault is a new type of structure with clear mechanical behavior and efficient material utilization. The paper aims to discuss this issue.Design/methodology/approachThe geometrical configuration of this structure is analyzed, and the geometrical modeling method is proposed. When necessary parameters are determined, such as the structural span, length, vault rise, longitudinal and lateral giant grid number and section height to top chord length ratio of the lattice member, the structure geometrical model can be generated.FindingsNumerical models of giant orthogonal grid barrel vaults with different rise–span ratios are built using the member model that can simulate the pre-buckling and post-buckling behavior. So the possible member buckle-straighten process and the plastic hinge form–disappear process of the structure under strong earthquake can be simulated.Originality/valueSeismic analysis results indicate that when the structure damages under strong earthquake there are a large number of buckling members and few endpoint plastic hinges in the structure. Dynamic damage of giant orthogonal grid barrel vault under strong earthquake is caused by buckling members that weaken the structural bearing capacity.

Shape Optimization and Stability Analysis for Kiewitt Spherical Reticulated Shell of Triangular Pyramid System

The Kiewitt spherical reticulated shell of triangular pyramid system is taken as the object of this study; a macroprogram of parametric modeling is developed by using the ANSYS Parametric Design Language. The minimum structural total weight is taken as the objective function, and a shape optimization program is proposed and compiled by adopting the sequence two-stage algorithm in FORTRAN environment. Then, the eigenvalue buckling analysis for Kiewitt spherical reticulated shell of triangular pyramid system is carried out with the span of 90 m and rise-span ratio of 1/7~1/3. On this basis, the whole nonlinear buckling process of the structure is researched by considering initial geometrical imperfection. The load-displacement curves are drawn, and the nonlinear behaviors of special nodes are analyzed. The structural nonlinear behaviors affected by rise-span ratio are discussed. Finally, the stability of reticulated shell before and after optimization is compared. The research results show that (1) users can easily get the required models only by inputting five parameters, i.e., the shell span (S), rise (F), latitudinal portions (Kn), radial loops (Nx), and thickness (T). (2) Under the conditions of different span and rise-span ratio, the optimal grid number and bar section for the Kiewitt spherical reticulated shell of triangular pyramid system existed after optimization; i.e., the structural total weight is the lightest. (3) The whole rigidity and stability of the Kiewitt spherical reticulated shell of triangular pyramid system are very nice, and the reticulated shell after optimization can still meet the stability requirement. (4) When conducting the reticulated shell design, the structural stability and carrying capacity can be improved by increasing the rise-span ratio or the rise. (5) From the perspective of stability, the rise-span ratio of the Kiewitt spherical reticulated shell of triangular pyramid system should not choose 1/7.

Nonlinear in-plane elastic buckling of a laminated circular shallow arch subjected to a central concentrated load

This paper investigates the in-plane elastic buckling of a laminated shallow circular arch subjected to a central concentrated load based on the classical laminated theory (CLT). Nonlinear equilibrium equation is established by using the principle of minimum potential energy, from which analytical solutions of the nonlinear in-plane elastic equilibrium path and buckling load are derived for laminated circular shallow fixed arches fixed. The critical modified slenderness ratio which switches the buckling characteristics is also obtained. The finite element (FE) simulation and experiments employing displacement control are conducted to verify the accuracy of the analytical solutions. A parametric study is then carried out and results are presented in both tabular and graphical forms to analyze the effects of the ply angle and thickness of laminates, and rise-span ratio of the arch on the critical bucking load and nonlinear equilibrium path of laminated arches.

Dynamic Response Analysis of 200m Honeycomb Lattice Domes by Rise Span Ratio

Dynamic Response Analysis of 200m Honeycomb Lattice Domes by Rise Span Ratio

Investigation on wind tunnel experiments of ridge-valley tensile membrane structures

In this study, we aim to investigate the wind pressure acting on ridge-valley tensile membrane structures through wind tunnel experiments. The experimental models were designed according to the statistics of practical engineering projects. Wind tunnel experiments were performed to investigate the effects of wind direction, rise-span ratio, eaves height and terrain roughness. The closed and open structures were both considered. The wind force coefficients were determined experimentally to analyse the mean wind pressure on the entire roof. Subsequently, the mean wind pressure coefficients were obtained to analyse the mean wind pressure distribution. Results show that the mean wind pressure is highly affected by wind direction and rise-span ratio. The terrain roughness exhibits a mild influence on the mean wind pressure, whereas the eaves height exhibits minimal influence. Additionally, the peak wind pressure coefficients were calculated to evaluate the effects of wind direction and rise-span ratio. Clustering analysis was performed to establish a zoning method of wind pressure, which has been proven reliable. Accordingly, the corresponding wind pressure coefficients of zone for the main wind-force resisting system and for the cladding were suggested. The outcomes of the wind pressure analysis, wind pressure coefficient of zone and zoning method for this type of structures are expected to be useful to engineers and researchers.

Damage model and damage assessment for single-layer reticulated domes under exterior blast load

Long-span reticulated dome is often considered as a landmark building of a region, so it is very important to investigate the dynamic response and propose the damage assessment method of reticulated dome under blast loading. In this article, a fine finite element model of Kiewitt8 (K8) single-layer reticulated dome was established by using ANSYS/LS-DYNA. The effects of standoff distance, charge weight, rise–span ratio, span, and roof weight on the responses of K8 single-layer reticulated dome were numerically studied. The results showed that the blast-resistant performance of reticulated dome with smaller rise–span ratio and larger span under exterior blast load was more advantageous. Although the blast-resistant capacity of reticulated dome with large span and large roof weight was favorable, the plastic deformations of reticulated dome members were small and the utilization of material was low at failure state. According to the dynamic response characteristics of plentiful K8 single-layer reticulated domes at different damage levels, a damage model of K8 single-layer reticulated dome under exterior blast load was proposed in this article to indicate the damage level and determine the ultimate strength. Besides, a new damage criterion for K8 reticulated dome was also defined. This damage model was defined based on the physical phenomena at different damage levels, which made the strength failure criterion had definite physical meaning. Using the proposed damage criterion and a new search algorithm for pressure and impulse, the pressure–impulse diagrams for the typical K8 reticulated dome were derived from the numerical simulations to evaluate the damage level of reticulated dome under blast loading. Finally, a method to determine the safety standoff distance for reticulated dome under given TNT charge weight was also proposed.

Effects of initial up-warp deformation on the stability of the CRTS II slab track at high temperatures

Initial up-warp deformation is one of the key factors that affect the stability of the China Railway Track System type II (CRTS II) slab track. Through modeling analysis, we studied the effects of different initial up-warp conditions on the deformation and stability of a slab track at high temperatures. Based on the theory of ‘variable span length’ in continuous welded rail (CWR), a vertical stability analysis model of the CRTS II slab track was established using the finite element method (FEM), and a scale model test was conducted. The effects of initial up-warp deformation features, such as rise displacement, span length, and line type on the stability of track slabs at high temperatures were studied through simulation. Results showed that the trends of vertical displacement were almost the same based on the FEM, analytical method, and on-site testing, but there was a better agreement between results from the FEM and the analytical method. When the span length was 6.5 m and the rise displacement of the initial up-warp reached 15 mm, compressional destruction was most likely to occur on the concrete at the bottom of the apex. The rise-span ratio of the slab up-warp reached its maximum when the initial up-warp span was 6.5 m at high temperatures. It is easier for track slabs to maintain their original form at a high temperature when there is an angle at the apex or a smooth boundary. However, with a smooth boundary, the concrete at the bottom of the apex is more likely to suffer compressional destruction. Therefore, to ensure the stability of the CRTS II slab track, an initial up-warp with a span of 6.5 m and a rise of 15 mm should be avoided, and the effects of different line types of the initial up-warp also need to be considered.

Simlating the Stability and Pre-stressed Tension of a Single-Layer Spherical Reticulated Shell Supported by Cable

Along with other developments that have occurred in this era, building requirements include not only function and practicality but also encompass architectural elegance such as lighting and light-weight structures. Conventional latticed shell triangulation creates a poor architectural effect as well as mediocre lighting and excessive and cluttered componentry. A latticed shell with quadrilateral meshing is light and has excellent lighting properties, but it also has low rigidity and inferior stability. This study addresses this problem by deploying in-plane stayed cables and horizontal and vertical cables out-of-plane via a strut, and by developing a new single-layer spherical latticed shell system supported by cables. The effects that various parameters have on the mechanical properties of this structures such as the rise-span ratio, asymmetric load distribution, strut length, initial defects and cable pre-stress, are investigated based on mechanical responses such as structural displacement, internal force, critical bearing capacity and the instability modal. The basic rules of structural stress are summarised and examples of 100 m and 150 m large span latticed shell structures are used to verify and analyse the rules for the mechanical properties of this structure, and to investigate how applicable this type of architecture is in a large-span structure. Based on the sequence used to tension the cable(s) during construction, several plans for pre-stressing in-plane and out-of-plane cable(s) are also proposed. The effect that this pre-stressing sequence has on structural properties such as maximum displacement and critical bearing capacity is investigated at each stage of construction via a numerical simulation of the structure. A proper procedure for constructing this structure is also proposed to provide theoretical support for an actual project.

Equivalent Static Wind Loads on Single-Layer Cylindrical Steel Shells

AbstractWind tunnel tests were carried out in an open terrain to measure the wind pressure on six cylindrical roofs with the rise-span ratios of 1/4, 1/6, and 1/8 and length-span ratios of 1 and 2....

Dynamic response of single-layer reticulated shell with explosion-protection wall under blast loading

To investigate the structural dynamic response of long span reticulated shell under external blast loading considering explosion-protection wall, explicit finite element (FE) programme LS-DYNA is used to set up the analytical model of explosion-protection wall corresponding to an experiment to grasp the propagation law of blast shock waves around the wall. The results of simulation and experiment are compared and the results verify the creditability and applicability of numerical simulation by using ALE (Arbitrary-Lagrange-Euler) algorithm. A Kiewitt8 single-layer reticulated shell of refinement with span of 40 m is established to simulate the responses of structure considering explosion-protection wall, which contains reticulated shell member, purlin hanger, purlin, rivet and roof boarding. According to simulation results from the maximum nodal displacement, average plastic strain and yielding degree of cross section of reticulated shell member, the dynamic response laws are proposed based on varying parameters, including height, position, length, material of the explosion-protection wall, rise-span ratio of reticulated shell and TNT explosive weights. Meanwhile, the influence rules of explosion-protection wall and structure on diffraction and reflection action of blast shock wave are obtained. In addition, the adverse height of the explosion-protection wall for reticulated shell with span of 40 m under external blast loading is proposed. Four damage types of reticulated shell with the explosion-protection wall subject to external blast loading are defined by summarizing all the structural response of FE numerical models, which could provide reference for reasonable explosion-proof design for reticulated shell structure.

The Seismic Response According to Rise-Span Ratio of the Arch Structure With Seismic Isolation

The Seismic Response According to Rise-Span Ratio of the Arch Structure With Seismic Isolation

Seismic response and failure mechanism of single-layer latticed domes with steel columns and braces as substructures

Seismic response and failure mechanism of single-layer latticed domes with steel columns and braces as substructures are studied using incremental dynamic analysis in the paper. The member models considering cyclic buckling and low cycle fatigue of steel are used in the analyses. The results show that the seismic responses will be greatly influenced by the material low cycle fatigue under strong earthquakes in different ways for the domes with different parameters. Two typical failure modes are found for the structures: one is the failure of domes and the other is the failure of both the dome and the substructure. Influence of rise-span ratio of domes, brace sections and column sections in substructures on the ultimate PGA and yielding PGA are studied, and the optimized values of the parameters are suggested for structural designing.

Characteristics of Wind Load on Spatial Structures with Typical Shapes due to Aerodynamic Geometrical Parameters and Terrain Type

The characteristics of wind load on large‐span roofs are complicated by their unique geometrical configurations and strong dependence on aerodynamic geometrical parameters and terrain type. However, there is rarely comprehensive research for characteristics of wind load on spatial structures due to aerodynamic geometrical parameters of roofs and terrain type. In this study, first, the effects of geometrical parameters of roofs and terrain type on the wind pressure distribution based on the data obtained from the existing wind tunnel tests were summarized. Then, the wind loads of full‐scale structures were predicted by CFD, and the efficiency of numerical results was further verified by the available wind tunnel tests on spatial structures. Finally, with comparative analyses of the wind pressure distribution of the roofs predicted by CFD under different cases, the effects of shape ratios, especially rise‐span ratio, height‐span ratio, length‐span ratio, and so on, and terrain type on the wind pressure field of typical spatial structures were presented. It can be beneficial to wind‐resistant design of structures and can be provided as reference for aerodynamic design optimum of span spatial structures.

Buckling characteristics according to the rise-span ratio of span 300m single-layer latticed dome

Buckling characteristics according to the rise-span ratio of span 300m single-layer latticed dome