Rise-span Ratio Research Articles

Tension and Deformation Analysis of Suspension Cable of Flexible Photovoltaic Support under Concentrated Load with Small Rise-span Ratio

The suspension cable structure with a small rise-span ratio (less than 1/30) is adopted in the flexible photovoltaic support, and it has strong geometric nonlinearity. Based on the principle of energy, the increment of cable force and the change of cable displacement under concentrated force are derived for the suspension cable in an equilibrium state under uniform distributed load, and the equivalent bending stiffness of simply supported beam under bending is given. Considering the strain energy generated by cable force variation, the method presented in the paper has higher calculation accuracy for suspension cable structures with a small rise-span ratio, and includes the special case of a large rise-span ratio. An engineering example of flexible photovoltaic support with a span of 15m is calculated and analyzed, and then compared with the finite element calculation results. The results show that the calculation error is less than 1% when the rise is 0.4 m, and the calculation error is less than 3% when the rise is 1.5m. The calculation formula in the paper is simple and accurate, which can provide a reference for static analysis and structural design of flexible photovoltaic support.

Analiza granične nosivosti zidanih svođenih mostova

To accurately evaluate the ultimate bearing capacity of masonry arch structures, considering the friction and bonding relationships between different components, a finite element model was established in this study with cohesive zero-thickness elements. The model was analysed using explicit dynamic simulations and verified through a case study. The results indicate that the thickness of the arch backfill and ring has a quadratic positive correlation with the ultimate bearing capacity of the structure, whereas the rise-span ratio has a cubic relationship. In particular, there is an optimal rise-span ratio (f/l = 1/3.909) to increase the bearing capacity of the structure under the same conditions.

Investigation on in-plane structural behavior of steel arches with rectangular web-openings

This study presents an experimental study and a finite element analysis of the in-plane structural properties of steel arches with rectangular web openings under static loading. The failure mode, deflection, section stress distribution, and other mechanical properties of three steel arch specimens with equidistant rectangular web openings are investigated. It is found that the ultimate load capacity, ductility, and stiffness of the steel arch decrease owing to large-scale openings compared with small-scale openings. The ultimate loading capacity and stiffness of the web-opening steel arches can be improved by welding stiffeners on the edge of the opening. In addition, 52 finite element models are established for parametric analysis to investigate the influence of the steel arch and stiffener geometries on the structural performance. The results show that increasing the rise-span ratio and web and flange thickness increase the ultimate loading capacity of the steel arch. A larger opening will cause the ultimate loading capacity and ductility to decrease significantly. The ultimate loading capacity of the steel arch is affected by horizontal stiffeners, whereas ductility is affected by both horizontal and vertical stiffeners. Finally, this study provides design recommendations to serve as engineering design references.

An analysis of the elastic-plastic seismic response of inner and outer cable-supported latticed shell structures

This paper studies the elastic-plastic seismic response of 12 inner and outer cable-supported latticed shell structures under fortification intensity and rare earthquakes. The influencing factors of the 12 models were analyzed. These included span, initial pretension, bottom structure form, connection condition of support, rise-span ratio, and inner cable-supported latticed shell span. Based on the calculation results, we summarize the plastic region of the top latticed shell and the plastic development extent under 7-degree and 8-degree fortification intensity and rare earthquakes, the post-seismic cable force changes, and the development characteristics and distribution rules of residual deformation of top latticed shell. Our investigation indicates that the span, bottom structure form, and connection condition of the support are most sensitive to the elastic-plastic response of the inner and outer cable-supported latticed shell. A strong earthquake can cause a loss of pretension, which primarily happens at inner looped cables and inner inclined cables of the inner cable-supported latticed shell. Cable force change is more sensitive to the asymmetric bottom structure, the latticed shell with a high rise-span ratio, and the span of the inner cable-supported latticed shell. The inner and outer cable-supported latticed shell model loses less cable force after a strong earthquake, and the post-seismic loss ratio is less than 10%, even under the impact of a severe, 9-degree earthquake.

Wind-Induced Response Characteristics and Equivalent Static Wind-Resistant Design Method of Spherical Inflatable Membrane Structures

The wind-induced responses and wind-resistant design method of spherical inflatable membrane structures are presented in this paper. Based on the wind pressure data obtained from wind tunnel experiments, the characteristics of wind-induced responses are studied via nonlinear dynamic time–history analysis, considering the influences of spans, rise–span ratios, internal pressures, wind velocities, and cable configurations. The results show that with the increment of wind velocity, the position of the maximum displacement changes from the top to the windward region, which usually leads to the exceedance of the displacement limitation. Under high wind velocity, enhancing the internal pressure can effectively reduce deflection. However, the membrane stress will also increase. Particular attention should be paid to checking the strength. The restraint effect of cross cables on wind-induced response is better than radial cables. Furthermore, an equivalent static analysis method for the wind-resistant design of spherical inflatable membrane structures is developed. The empirical formulas and recommendation values of gust response factors and nonlinear adjustment factors are provided for engineering reference.

Research on bearing capacity of honeycomb plate box-type hollow roof structure

• A new type of honeycomb plate box-type hollow roof structure is prepared with good ductility. • The validity of the numerical analysis model was verified by comparing the results of experiment with the results of the coupling model. • Influential factors on the bearing capacity of honeycomb plate box-type hollow roof structure obtained by parametric analysis. In this paper, a new type of honeycomb plate box-type hollow roof structure was prepared. The failure modes and mechanical properties of the box-type hollow roof structure were analyzed by bearing capacity test and numerical simulation. The validity of the numerical analysis model was verified by comparing the results of experiment with the results of the coupling model. The influence of specification of honeycomb plate, height of the side plate, rise-span ratio of the structure, configuration of box-type hollow roof structure, and initial geometric defect on the bearing capacity of the honeycomb plate box-type hollow roof structure were analyzed. The results show that the failure mode of the specimen is tensile failure of the surface plane of the honeycomb plate with strengthened frame and buckling instability of the plate near the joint. The results of coupling model are in good agreement with the results of experiment. The stiffness of honeycomb plate box-type hollow roof structure can be improved by the thickness of plate and the height of core layer of honeycomb plate. The ultimate bearing capacity of the honeycomb plate box-type hollow roof structure increases with the increase of the height and rise-span ratio. The bottom plate of box-type hollow roof structure can make the force transmission path of the structure more reasonable and effectively reduce the phenomenon of stress concentration. Compared with the structure without initial geometric defect, the stable bearing capacity of the structure is reduced by 18.6 % and the ultimate bearing capacity is reduced by 28 % when the initial geometric defect of 80 mm is applied to the structure.

Experimental Study on Aeroelastic Instability of Spherical Inflatable Membrane Structures with a Large Rise–Span Ratio

Spherical inflatable membrane structures are extremely prone to suffer aeroelastic instability under strong winds, which requires detailed investigation. In this paper, based on the digital image correlation technology (DIC), the displacement and strain response characteristics under wind loads are investigated. Furthermore, the aeroelastic instability characteristics and the criteria for determining the occurrence of this phenomenon are defined. The results show that the top, windward, and side parts of the structure deform upward, inward, and outward. The extreme value of the total displacement occurs at approximately 1/2 of the windward region. Maximum principal strains occur at the windward and leeward centers together with the top region. After the wind speed exceeds the critical value (the dimensionless critical wind speed is observed at 1.37), the structure undergoes a sudden change of dominant vibration mode, the damping ratio decreases dramatically and reaches nearly zero. It can be concluded that the aeroelastic instability of the spherical inflatable membrane structure is caused by vortex-induced resonance and is characterized by a sudden increase in deformation and amplitude, a sudden change of the dominant vibration mode, and a rapid decay of the damping ratio. The Reynolds number after reaching the instability critical wind speed is Re > 3.1 × 105.

Random vibration and structural reliability of composite hyperbolic–parabolic membrane structures under wind load

The paper presents the random vibration and structural reliability of composite hyperbolic–parabolic membrane structures under wind load. First, the non-linear random vibration equation of the hyperbolic–parabolic membrane structures is established by the moment-free theory of thin shells, von Karman’s large deflection theory, and the potential flow theory. The results of random dynamic responses are obtained with the Fokker Planck Kolmogorov equation method (FPK) solving the equation. Then, the structural performance function of composite membrane structures is established based on the Displacement First Passage Failure Criteria (DFPFC) and the results of random dynamic responses. Furthermore, the reliability index (RI) of the performance function is calculated by the JC method. Finally, the theoretical model proposed is validated by experimental investigation utilizing the Monte Carlo sampling method (MCS). Additionally, the influence of wind speed, pretension force, and rise–span ratio on hyperbolic–parabolic membrane structure reliability is analyzed. The paper can provide important references for the design and analysis of membrane structures.

Robustness study of fabricated single-layer grid shell structures based on component sensitivity and vulnerability

Using discrete beam elements (DBE) to simulate the mechanical properties of assemble joints, the refined analysis model of fabricated single-layer grid shell structures for progressive collapse simulation was established. Based on the component sensitivity and vulnerability, the evaluation indexes of component importance and structural robustness were proposed. The effects of meshing sizes, rise-span ratios and connection behaviors on the collapse performance of K6 type spherical surface grid shell were also investigated. The following conclusions are mainly obtained: (1) By conducting the integral scaled model test, the accuracy of the refined analysis model was verified. (2) Considering the sensitivity and vulnerability of components, the evaluation indexes of component importance and structural robustness were proposed, and the reliability of the component importance coefficient was examined. (3) The effects of grid sizes, rise-span ratios and connection behaviors on the collapse performance of the gird shell were studied, and the rules of structural collapse loads changing with grid sizes and rise-span ratios were explained. (4) To ensure the structure with good collapse resistant capacity, the rise-span ratio should not be less than 1/4 for the K6 type spherical surface grid shell, and failure of the connection region should be avoided.

Model test study on static performance of rib-patterned small rise-span ratio suspend-dome structure

To investigate the distribution characteristics of prestressing force and static characteristics of the rib-patterned small rise-span ratio suspend-dome structure, a 1:20 scaled model of the Lanzhou Olympic Gymnasium roof structure was established. During to the small-scale ratio model with dense nodes, according to the principle of constant structural stiffness, a multi-node synchronous loading device was designed. The construction tensile loading test and multi-stage static loading test were carried out. The axial force of rods, vertical displacement of nodes, and radial displacement of supports for the model with initial geometric imperfection under 11 load cases were tested. Test results were used to validate and then refine the numerical simulation using ABAQUS. The study shows that a multi-node synchronous loading device dramatically improved the loading efficiency and satisfied the accuracy requirement of the test. The test results were in good agreement with the simulated results, which verified the correctness of the finite element modelling method, the accuracy of the test method, and the rationality of the measuring point arrangement. The small rise-span ratio suspend-dome structure with a rib-patterned has good elasticity at a low load level. The full-span arrangement of the live load is the most unfavorable load case of the structure. The outer loop cable bearing capacity exhibited a higher proportion. The third ring rod was found to sustain the highest load, the outer ring rod is more sensitive to load, and the fourth circle node was found to have the largest vertical displacement in the model. The change of support displacement in practical engineering should not be neglected.

Wind tunnel experiment on rectangular-shaped arch-supported membrane structures

This paper highlights the investigation of wind tunnel experiment on rectangular-shaped arch-supported membrane structures. Series of wind tunnel experiments are carried out to record the time history of pressure under different wind directions for both enclosed and open structures. In order to present the comparative analysis, contours and graphs for mean and peak wind pressure coefficients are plotted considering different parameters such as rise-span ratio, wind direction, and boundary wall. Study shows that under oblique wind direction, strong flow separation occurs in the windward arch edge which creates larger suction pressure coefficient on the immediate downside of windward arch. Based on area and intensity of negative pressure coefficient, 45⁰ is the most critical wind direction. Influence of rise-span ratio is noticeable. When rise-span ratio increases from 0.2 to 0.35, pressure coefficient increases significantly, however when rise-span ratio further increases to 0.5, increase in pressure coefficient is marginal. Moreover, in order to ease the engineering design application, roof surface is divided into different zones and assigned with mean and peak wind pressure coefficient.

Impact of saddle membrane structure by hail with combined particle sizes: Numerical simulation and experimental investigation

In this paper, the impact of the hail with the single and combined particle sizes on the saddle membrane structure is studied by experiments and numerical simulations. In the experiment, the hail particles fall at a certain height and hit the membrane, while the dynamic response of feature points on the membrane and the cable tension is monitored. Then the saddle membrane structure impacted by the hail particles is simulated by the finite element software ANSYS/LS-DYNA. As shown by the numerical simulation and experimental results, even though the combined particle size hail load is not enough to cause direct damage to the membrane, large deformation of the saddle membrane structure will be produced by the impact. Meanwhile, the tension of the cable is greatly reduced, and the maximum relaxation rate reaches as high as 25.12%. In addition, the membrane displacement induced by hails decreases with the increase of the rise-span ratio and pretension. Therefore, the pretension relaxation induced by the hail impact should be considered in the design of the membrane structure. The stiffness and stability of the structure can be improved by increasing the rise-span ratio and pretension. The pretension should be monitored regularly so that the maintenance of the secondary tensioning can be carried out in time.

The Investigation on Static Stability Analysis for Reticulated Shell with Initial Defect Value Using Stochastic Defect Mode Method

Regarding the effect of the initial geometric defect (IGD) on the static stability of single-layer reticulated shells, its distribution pattern and magnitude are the main concerns to researchers. However, the suitable selection of the initial geometric defect magnitude (IGDM) is still a controversial topic. Therefore, it is intended to study the determination of the proper IGDM based on the structure force state (SFS) and the defect coefficient. In order to find out a qualified IGDM, more than 5200 numerical cases are carried out for four types of commonly used single-layer reticulated shells with the span ranging from 40 to 70 m and the rise–span ratio from 1/4 to 1/7, within the random defect mode method, by taking both geometric and material nonlinearity into account. The results show that it is more feasible to set the L/500 as IGDM when evaluating the stability of the single-layer reticulated shell. In addition, an updated criterion to identify the SFS at the stability critical state (SCS) is developed.

Wind Pressure Characteristics Based on the Rise–Span Ratio of Spherical Domes with Openings on the Roof

Wind loads are a primary concern in dome roof structures with openings such as retractable dome roofs. This is because the openings can cause damage to the cladding owing to high internal pressure. In this study, the wind pressure characteristics of a dome with an opening that varied based on the opening, rise–span ratio, and height span were examined by comparing the results from wind tunnel tests with those from previous studies. The negative pressure dominated the internal pressure of the roof in all regions and was not significantly affected by changes in the rise–span and height–span ratios. The reattachment distance of the windward region increased as the rise–span ratio increased, increasing the negative net pressure and decreasing the positive net pressure owing to a relatively large vortex. The roof inclination angle of the leeward region decreased as the rise–span ratio decreased, resulting in a decrease in the negative net pressure and an increase in the positive net pressure owing to a relatively small vortex. Based on the experimental results, a peak net pressure coefficient for cladding design was proposed for an open dome roof with a rise–span ratio of 0.05.

Experiment and Analysis of Seismically Isolated Single-Layer Cylindrical Reticulated Shell Structure

To explore the seismic response, influence mechanism, and failure of long-span spatial structures with three-dimensional seismic excitations in a strong earthquake, 1/6-scale shaking-table tests of single-layer cylindrical reticulated shell structures with fixed hinged bearings, horizontal isolation bearings, and three-dimensional isolation bearings were conducted with three-dimensional seismic excitations. The accuracy of the numerical simulation method was verified by a numerical reconstruction analysis of the experiments. Dynamic time-history response analysis and incremental dynamic analysis of a full-scale single-layer cylindrical reticulated shell were conducted. The seismic response and failure states of the three-dimensional isolation structure were compared at different positions, different rise-span ratios, and different lower supporting structure heights. Studies have shown that horizontal isolation bearings cannot reduce the vertical vibration frequency and vertical seismic response of a structure; three-dimensional isolation bearings can effectively reduce the vertical vibration frequency and the vertical seismic response of the structure. The degree of plastic development is reduced by 82% in strong earthquakes; the initial plastic development position of the structure changes from the midspan to the four edges, and the ultimate bearing capacity of the structure increases by 40%. For a three-dimensional isolation structure, the natural frequency of the base-isolation structure is smaller, the ultimate bearing capacity is greater, and the isolation effect is better than with story isolation. With an increase in the rise-span ratio, the ultimate bearing capacity of the structure decreases. When the rise-span ratio is 1/2, the bearing capacity is 0.9g, and the structure tends toward dynamic instability. A greater height for the lower support produces a greater ultimate bearing capacity and better isolation.

Modeling of the added mass of air on ETFE cushions vibrating in still air

ETFE (Ethylene-Tetra-Fluoro-Ethylene) cushions are popularly used in civil engineering structures. A vibrating ETFE cushion will drive the surrounding still air in motion and the inertia of air produces an action on the cushion which is known as the added mass. This effect is usually significant due to the light weight of ETFE cushions. This paper proposes a new model on the added mass effect for a close-type ETFE cushion vibrating in still air with improved accuracy compared with other existing models. The fluid velocity along the z-direction of the enveloping membrane from perturbation of the vibrating cushion is assumed to vary in the form of a quartic function. The added mass is analytically obtained from the Laplace equation. This new formulation is then validated by comparing the dynamic responses of square ETFE cushions with those from the fluid–structure interaction (FSI) analysis and other methods in the literature. The accuracy of the proposed approach is further investigated for different rise–span ratio, initial inner pressure, side length, Young’s modulus and membrane thickness of the ETFE cushion. It may be concluded that the proposed approach is more accurate than existing methods with more realistic predictions on the actual variation of the fluid velocity along the z-direction above the cushion and the errors are less than 4% for practical ranges of influencing parameters studied.

Seismic Performance of Kiewitt-Sunflower Single Layer Spherical Reticulated Shells

In this paper, seismic behavior of Kiewitt-Sunflower single layer spherical reticulated shells is examined within the time history method, based on our proposed damage constitutive model for thin-walled circular steel tubes. According to a large number of numerical examples, the failure mode of this kind of single layer spherical reticulated shell in the case of earthquake is figured out. In addition, the effect of the damage accumulation, rise-span ratio, initial geometric imperfection, types of seismic wave and amplitude modulation ratio on the dynamic response of the shell structure is explored. Finally, a structural damage factor is proposed and it has a good match with the numerical results, which is productive to assess the damage and failure behavior of such structures suffering the earthquake and post-earthquake.

Deformation properties of arched glass fiber reinforced plastics structure under static load: Considering the soil cover and rise-span ratio

In this study, the load level, soil cover height, rise-span ratio, and arch foot constraint state were utilized to explore the mechanical properties of buried arch glass fiber reinforced plastics (GFRP) structures. Through the indoor scale-down test, the stress and deformation of arched GFRP structures under different load and soil cover height were investigated. Additionally, through the three-dimensional finite element method, the influence of the rise-span ratio and the constraint state of arch foot on the mechanical properties were obtained. The results indicate the new buried composite arch structure has excellent bearing capacity for the possible traffic load. Simultaneously, the semi-elliptical arch structure was believed to outperform the semi-circular arch structure when considering the external load. Specifically, increasing the soil cover height and reducing rise-span ratio were found to achieve the load-reduction effect.

Static performance of a new type of corrugated steel-concrete composite shell under mid-span loading

This paper proposes a new type of corrugated steel-concrete (CSC) utility tunnel, which is composed of CSC shells. Compared with existing prefabricated concrete utility tunnels, the CSC utility tunnel reduces the requirements for transportation and hoisting and provides additional protection for concrete and rebars from corrosion. The performance of the CSC utility tunnel depends on the behaviors of CSC shells. First, cross-sectional properties were studied by theoretical analyses and it was found that the stiffness can be greatly improved if corrugated steel and concrete work together, reaching 1.43 times that of the simple superposition of corrugated steel and concrete, respectively. To further disclose the fundamental behavior of the CSC shell, six CSC shell specimens with a span of 3 m and different stud intervals (from 100 mm × 100 mm to 400 mm × 400 mm), rise-span ratios (1/10–1/6) and concrete strengths (32.1 MPa and 51.2 MPa) were tested under a static mid-span load. The test results show that all CSC shells failed by strength failure when reached the ultimate load. For specimens with different stud intervals, the strains of the corrugated steel (crest, middle and trough) were measured, and then the composite mechanism between steel and concrete and the confinement effect of corrugated steel to concrete were analyzed. The stud interval has a slight influence on the ultimate bearing capacity in this study, decreasing by 7.5% for the bearing capacity when the stud interval increases from 100 mm × 100 mm to 400 mm × 400 mm. The bearing capacity and the stiffness of the CSC shell decrease obviously with the decreasing of the rise-span ratio. And the bearing capacity improves significantly with the improvement of the concrete strength. Furthermore, a finite element model was developed and was proved to have good accuracy for the prediction of the performance of the CSC shell.

Influence of different material parameters on nonlinear vibration of the cylindrical skeleton supported prestressed fabric composite membrane

Abstract In order to study the influence of geometric nonlinearity and material parameters on the free vibration behavior of the cylindrical skeleton supported prestressed fabric composite membrane. In this paper, based on von Karman's large deflection theory and D’Alembert's principle, the governing equations of nonlinear viscous damped prestressed free vibration of frame supported anisotropic membrane structures were established. By using Galerkin and KBM perturbation method, the analytical expressions of frequency function, displacement function and mode shape of nonlinear free vibration were obtained. In order to verify the effectiveness and effective range of the method, the fourth order Runge-Kutta method was used for numerical calculation. The calculation examples of membrane material parameters were given. The calculation and analysis of different membrane prestress, different length width ratio, different rise span ratio and different material parameters (elastic modulus ratio, viscous damping and material density) were carried out. The results were compared with the numerical results obtained by Runge-Kutta method to verify the accuracy of the method. The research results of this paper provide a theoretical reference for the selection of membrane materials, the subsequent calculation of wind-induced stability of steel skeleton membrane structure and the design of wind-driven rain resistance.