Large-span Structures Research Articles

Multi-constrained topology optimization of prefabricated joints in large-span latticed structures

In recent years, topology optimization (TO) has shown great potential in the optimal design of engineering structures. In this study, a parameterized level set (PLS) method capable of solving the compliance minimization problem with both stress and volume constraints is proposed to improve the design efficiency of nodal connections in large-span latticed structures. 3D topology optimization of assembled hub (AH) joints is conducted based on the proposed method. The performances of the optimal designs are compared with those of the traditional joints in terms of volume, stress distribution and compliance value. Different connection types and complex loading conditions are considered to satisfy the requirements of engineering practice. It is indicated that the proposed PLS method exhibits good stability and high computing efficiency during the optimization of AH joints. Compared with the study cases with a single volume constraint, the maximum von Mises stress is effectively controlled by simultaneously introducing the stress and volume constraints. In addition, the variation in the volume constraint has much greater influence on the compliance results than the stress constraint. The compliance continuously increases when the volume constraint decreases from 100% to 40%, while the difference in compliance is less than 1.5% with or without stress constraints. It is demonstrated that the performances of AH joints are significantly improved after the TO design. The reduction rates of mass are in the range of 25.2 % to 35.2 %, and the compliance value is reduced by 0.5 % to 7.6 % for all the study cases.

Impact Dynamic Response of Spherical Net Shells: Finite Element-Based Computational Analysis Investigating the Influence of Dynamic Constitutive Models

The net shell is a widely utilized large-span space structure known for its aesthetically pleasing design and uniform load distribution, as well as serving as a prominent architectural landmark. In recent years, the impact resistance research of mesh and shell structures has garnered increased attention due to the accumulation of local conflicts. In this study, a parametric model of the spherical mesh shell was developed with Rhino software, and a numerical analysis model for a K8 mesh shell was established through the application of the ABAQUS finite element analysis software. Subsequently, the proposed numerical analysis method for the impact test was applied to validate its accuracy. The research also explored various dynamic constitutive models, such as Cowper-Symonds, Johnson-Cook, modified temperature term Johnson-Cook, and modified strain term and temperature term Johnson-Cook, with the assessment of their impact on the numerical simulation of impact resistance. Based on the impact dynamic response of the spherical net shell of different materials, the selection of an appropriate dynamic constitutive model for the numerical simulation of impact resistance in the spherical net shell was the MJ-C model. The comparative analysis of different materials, including Q235B, Q355B, Q460D, and 6061-T6, indicated that when the impact material failed to penetrate the structure instantly, the improvement of the material strength would enhance the impact resistance of the structure. On the other hand, when the impact material managed to penetrate the structure instantly, the material strength would not significantly help mitigate the damage. Notably, brittle materials, such as aluminum alloy, exhibited a distinct absence of a pronounced yield stage compared with low-carbon steel, which ultimately led to a relatively abrupt deformation.

A novel integrated sleeve-wedge anchorage system for multi-tendon CFRP cable utilized in cable roof structures: Concept and numerical investigation

Carbon fiber-reinforced polymer (CFRP) cables demonstrate exceptional mechanical properties and offer significant potential for utilization in large-span cable roof structures. However, the implementation of efficient CFRP cable anchorage systems specifically designed for cable roofs remains an urgent necessity. In this paper, a novel integrated sleeve-wedge anchorage system (NISWAS) consisting of two components, a multi-channel integrated sleeve-wedge (MCISW) and a barrel, has been proposed to achieve the anchorage of CFRP cable with multiple tendons. Compared to the traditional wedge-type anchorage system (WTAS), which can only clamp a single CFRP tendon, the use of the novel integrated steel wire anchorage system (NISWAS) reduces both the volume and self-weight of the cable anchorage end, significantly improving construction efficiency. The design concept of NISWAS was validated through finite element method (FEM) as an example of a 6-Φ5 CFRP cable, and its anchor performance was systematically evaluated. Three key factors affecting the anchor performance were analyzed: the slope angle of MCISW, the anchor length and the differential angle between barrel and MCISW. The results show that the NISWAS is an effective way of anchoring multiple CFRP tendons, and the design of the MCISW can prevent excessive transverse stress on the CFRP cable at the loaded end of the anchorage. The slope angle of the MCISW exerts the most significant impact on the anchor performance. The optimal choice of angle is 3°, beyond which the effect of the anchorage system on the sliding of CFRP cable becomes less significant, while excessive transverse stress may cause premature failure of the cable. The differential angle between barrel and MCISW has a secondary influence on the anchor performance. A moderate angle difference value (0.1° to 0.2°) can alleviate the transverse stress on the CFRP cable, but a too large value (more than 0.3°) will reduce the force transmission between the MCISW and barrel, resulting in premature cable pullout. Increasing the anchor length can reduce transverse stress and cable slip, but the reduction effect is not significant. After analysis, the anchor length of 90 mm can satisfy the anchoring requirement. According to the influence law of the above three factors, the parameter design scheme of the NISWAS was finally proposed.

ПРИМЕНЕНИЕ МОДУЛЯ ДИНАМИКА+ В ЛИРА-САПР 2022 ПРИ РАСЧЕТЕ БОЛЬШЕПРОЛЕТНЫХ ЗДАНИЙ ИЛИ СООРУЖЕНИЙ НА СЕЙСМИЧЕСКИЕ ВОЗДЕЙСТВИЯ

The article discusses the main goals of dynamic calculation of buildings and structures. The authors present a method for calculating a large-span steel spatial structure for seismic impacts using the Dynamics+ module in LIRA-CAD 2022 software package. The paper analyses the sequence of loading formation in the calculation scheme. It considers the cases when the calculation of buildings and structures for seismic impact must be carried out using accelerograms, seismograms or velocigrams. As a result, the authors obtained a calculation model that allows analyzing the dynamic behavior of a large-span spatial structure in different periods. Subsequently, it will be relevant for studying the resistance of this structure to progressive collapse under seismic impact.

Research and Optimization of Lateral Compressive Performance of the 3-D Printed Beetle Elytron Plate

In this paper, two types of beetle elytron plates (end-trabecular beetle elytron plate (EBEP) and middle-trabecular beetle elytron plate (MBEP)) and honeycomb plate (HP) were manufactured by 3-D printed and applied to large-span spatial structure. The lateral compressive performance of the 3-D printed beetle elytron plate was investigated by lateral compression bearing capacity test and numerical analysis. The influence of number of cylinders, ratio of the radius of the cylinder to the side length of the hexagonal honeycomb core (ratio of radius-length), thickness of core layer and configuration of beetle elytron plate on the lateral compressive performance of the beetle elytron plates were studied and the optimization method for lateral compressive performance of the beetle elytron plates was proposed. The result shows that the lateral compression bearing capacity of EBEP is greater than that of MBEP, and both are greater than of HP. The lateral compression bearing capacity of the beetle elytron plate with six cylinders is about 25% higher than that of the HP without cylinders. The lateral compression bearing capacity of beetle elytron plate can be improved by increasing the thickness of plates. The results of the study will promote the application of beetle elytron plates in large-span spatial structures.

Seismic response of a single-layer reticulated dome: Fault-to-structure simulation

Seismic response of large-span spatial structures is particularly susceptible to soil-structure interaction and spatial variability of ground motions. Yet existing seismic analysis fail to properly account for the foundation soil, and the ground motions are commonly determined based on empirical formulas. Physics-based 3D seismic simulation has recently been developed to provide site-specific ground motions, and the fault-to-structure simulation facilitates the incorporation of seismic wave field and soil-structure interaction into the analysis of engineering structures. This article innovatively implements the fault-to-structure simulation on a single-layer reticulated dome. Structural response of fault-to-structure model and two commonly used models is compared and discussed. Results show that the damping of soil reduces the stress and horizontal acceleration of the reticulated dome, while the soil movement leads to an increase in displacement. Noticeably, the seismic propagation characteristics increase vertical acceleration of the inner rings. Compared with fault-to-structure model, the multi-support excitation model and uniform excitation model reduce the vertical displacement of 29.1% and 50.1%, respectively, and reduce the vertical acceleration of the inner rings of 59.9% and 69.0%, respectively.

Research on Seismic Wave Delay and Amplification Methods in the Shaking Table Test of Large-Span Structures in Mountain Areas

The traveling wave and slope amplification effects should be considered in the shaking table test of large-span structures in mountain areas. Based on the structural characteristics and site conditions of a large-span structure in a mountain area, this paper designed a high-rise steel frame structure with viscous dampers through finite element analysis to amplify seismic waves with a time delay. Then, the original structure and steel frame models with a similarity ratio of 1/40 were made for shaking table tests. The test results showed that a high-rise steel frame structure with reasonable viscous dampers could delay and amplify seismic waves, and the scaled model of the structure could play the same role in shaking table tests. Meanwhile, by comparing the seismic responses of large-span structural models in mountain areas before and after the amplification of seismic wave delays, it was found that the delay and amplification of seismic waves had little impact on the acceleration response of the structure. In contrast, the seismic wave delay played a dominant role in the change in the structural displacement response.

Axial Compression Behaviour and Modelling of Pultruded Basalt-Fibre-Reinforced Polymer (BFRP) Tubes

Laminated fibre-reinforced polymer (FRP) tubes are increasingly used as compression members in large-span spatial structures due to their high bearing capacity, corrosion resistance, and superior stability compared to high-strength steel pipes. In this study, axial compression tests were conducted on slender BFRP tubes to evaluate their compression characteristics as compression members. The results indicated that BFRP tubes exhibited three distinct failure modes, namely local failure, critical failure, and buckling failure. Overall, buckling was identified as the primary mode of failure under compression. The stress–strain curves of BFRP tubes were characterized by three stages, including elastic, elastic-plastic, and plastic stages. To enable design-oriented approaches, two three-stage theoretical models for BFRP tubes were developed through experimental data analysis. The models predicted the stress–strain curves and the load-lateral deflection curves, taking into account the post-peak softening behaviour of the stress–strain curves. Comparisons between the test results and the predictions calculated using the proposed models indicated that they were in good agreement.

Influence of welding residual stress on bending resistance of hollow spherical joints

Welded hollow spherical joints are widely used in large-span spatial structures because of their simple organization and convenient construction. However, in the sphere-pipe connection welds of the joints, welding residual stress is generated, which will adversely affect the mechanical properties of the joints and the overall structure. In this paper, the parametric model of welded hollow spherical joints was established by employing the geometric configuration dimensions of those joints frequently used in engineering. Through the combination of experimental research and numerical simulation, the welding residual stress of welded hollow spherical joints and its impact on joints' bending resistance were studied. First of all, based on the distribution pattern of the stress, bending test of the joints was carried out and revealed the influence of welding residual stress on the bending stiffness and ultimate bending capacity of the joints; Then, through the results of experimental analysis and finite element calculation, and with parametric analysis, the impact of welding residual stress on joints' bending resistance was clarified with the variation of parameters such as the hollow sphere diameter D, wall thickness t and the connecting steel pipe diameter d. It is shown that welding residual stress has a great impact on joints' bending stiffness, with a reduction more than 10%, while it doesn't affect their ultimate bending capacity much, with an influence no more than 5%. In addition, as D increases, t, and d decrease, its impact on the bending resistance rises.

Spatial large-span structures

Objective. This article discusses spatial large-span structures; provides features of their work; as well as layout examples. General dimensions and ways of stabilizing displacements are given.Method. The features of the work and layout of spatial large-span structures; as well as calculation formulas are given. The types of sections and nodes of conjugation of elements are presented. A technique is described that allows stabilizing the movements of largespan pavements.Result. The given structural schemes; as well as the analysis of their work; allow designing large-span spatial systems in the form of convex and concave structures that have high reliability; minimal weight; and high manufacturability in manufacturing; transportation and installation.Conclusion. The proposed rational design solutions make it possible to reduce the own weight of spatial convex and concave coatings; which have the necessary rigidity; strength and stability. The types of structural schemes; sections and junctions of elements considered in the article are widely used in the practice of design and construction.

Intelligent safety assessment method for demolition construction of closure segment of long-span continuous rigid frame bridges

In order to clarify the risk of demolition construction of large-span continuous rigid structure bridge and put forward an intelligent safety assessment method to ensure the safety of demolition construction of the closure segment. Taking a concrete continuous rigid bridge as an example, this paper uses the combination of finite element analysis, theoretical calculation and actual measurement verification to study the influencing parameters and construction safety assessment methods of the long-span continuous rigid bridge in the demolition construction stage of the closure segment. The results show that the parameters that have a great influence on the stress state of box girder and pier during the demolition stage of the closure segment are mainly the self-weight of the structure, tendon prestress state and construction temperature difference. Through the influence envelope analysis of each parameter, it is clear that the ultimate failure mode caused by the most unfavorable parameter combination in the demolition stage of the closure segment is the crushing of the bottom plate of the box girder in the middle span, and the cracking of the piers on the side span at the top and the variable section. In order to further accurately evaluate the construction safety in the demolition stage of the closure segment, based on the long-term down-warping state inversion analysis of the box girder, the identification method of cross-section damage and prestress loss of the box girder and the calculation results of engineering examples are given. Finally, a safety assessment method of the most unfavorable section based on the principle of influence matrix is proposed. Through the analysis of an example, the safety of the closure segment demolition construction is clarified, and the correctness of the analysis is verified by intelligent monitoring means.

Life cycle carbon emission assessment of large-span steel structures: A case study

Buildings take up a significant part of global carbon emissions and are a major contributor to the climate crisis. Large-span steel structures usually consume more materials, need more complex construction processes, and thus have a larger environmental impact. This study presents a comparative analysis of the life cycle carbon emissions of three typical large-span steel structures, i.e., a cable dome, a reticulated shell, and a suspendome, based on a design case. A tiered hybrid method using the process-based life cycle assessment for the processes with emission factors and using input–output-based life cycle assessment for the processes without emission factors is proposed to assess the life cycle carbon emissions. Comparisons on the carbon emissions of the three structures reveal that the cable dome is the best of the three, having the lowest steel consumption and the lowest carbon emissions. Although the component production phase appears to contribute most of the total emissions, the construction phase is also of considerable importance in alleviating the present emission pressure, especially for the cable dome and suspendome. Further analysis shows that carbon emissions of large-span steel structures are not simply linearly related to steel consumption and need to be considered as a separate design objective. This study provides a useful reference for life cycle carbon emission assessment and low-carbon design of large-span steel structures.

A new configuration of Geiger-type cable domes with sliding ridge cables: Computational framework and structural feasibility investigation

Cable domes have been widely used in the field of structural engineering for their lightweight feature that is fit for large-span structures. Geiger-type cable domes have gained much attention due to their simple configurations. This paper proposes a modified Geiger-type cable dome with sliding ridge cables. Compared to conventional forms, the pre-stresses in the cables are more uniform, and the number of cables is fewer. An energy-based method is adopted to derive the equilibrium equations for the form-finding and load response analysis of the sliding cable system. The Levenberg-Marquardt algorithm is used to solve the non-linear equilibrium equations. A numerical example is employed to demonstrate the feasibility of the proposed structural form in terms of structural strength, stiffness, and stability. The influence of two design parameters, i.e., the force ratio of the hoop and ridge cables and the strut length, on the structural performance is investigated. In general, the new cable dome has better construction features and feasible mechanical properties and is believed to have the potential for practical applications.

Investigation on the mechanical behavior of glulam beam string

The glulam beam string, which is a new type of self-balancing system in the field of large-span glulam structures, was investigated systematically in this study.A series of five-point bending tests were conducted while accounting for variations in string diameter. The failure mode of the specimen varied from lower steel cable breakage to upper glulam beam failure with the diameter increasing. Parametric analysis was performed utilizing numerical models, which accounted for the difference in string diameter, pre-camber, and number of strut members, and a series of design proposals were provided considering both the bearing capacity and economic effect. Furthermore, theoretical formulas based on the Rayleigh-Ritz method were found to be effective in predicting the failure mode and calculating the bearing capacity with accuracy.

Study of temperature field in large-span steel structure under radiation-thermal-fluid coupling

Study of temperature field in large-span steel structure under radiation-thermal-fluid coupling

Analysis and Calculation of Large Span Dry-Coal Shed

The project of Wuhan Group Kunming Iron and Steel Co., Ltd., Promote the supply side structural reform and implement the special upgrading project of environment comprehensive raw material yard project ore yard (A to B) reticulated shell structure Located in Kunming Steel New Area, Cao pu Town, Anning City, Kunming City, Yunnan Province, 780m long, 50m high, the span is 147m (more than 120m), According to «Code for Seismic Design of Buildings» and «Technical points of special review on seismic fortification of high-rise buildings beyond the limit», it belongs to the out of gauge large-span space structure, Special review of engineering seismic fortification is required. The structural analysis of the project adopts SAP2000, MST2020, MIDAS Gen three kinds of software for calculation and analysis, And the individual model and the whole model are established respectively, Envelope analysis is carried out for two cases. Through linear elastic analysis, response spectrum small earthquake analysis, Medium earthquake analysis of response spectrum, elastic time-history analysis of small earthquakes, dynamic elastoplastic analysis of large earthquakes to analyze and calculate the deformation of latticed shells and the stress of membersl. Through a series of structural analysis and structural measures, To ensure that the reticulated shell and the lower part are coagulated on the short column and all performance indicators can meet the specification requirements. Through the structural analysis of two calculation models, ensure that all performance indicators can meet the specification requirements.

An adaptation resilience assessment framework for key components of prefabricated underground stations

Prefabricated underground stations (PUS) have become an important aspect of resilient cities. Adaptability to local emergency restoration is a critical target for PUS to achieve resilience after disasters. For this purpose, this study constructed a PUS adaptation resilience assessment framework (PUS-ARAF) with three modules: (1) A PUS key component vulnerability function was proposed to analyze its morphology. (2) A ‘Resilience performance - recovery Time - restoration Cost’ assessment process was established to analyze local emergency restoration. (3) A dynamic assessment was proposed to quickly obtain PUS adaptive schemes for key components. A case study was performed based on the Shenzhen PUS and the results indicated that (1) the Joint-region-weak-link scheme alleviated brittle damage on PUS large-span structures and achieved 0.97 bearing and 0.96 energy absorption capacities of continuous-section beam, (2) local emergency restorability exhibits conditional function characteristics with local factors. Threshold-compliant schemes demonstrate easy adaptation to local restorability at minimal cost. (3) PUS-ARAF developed local adaptive schemes with minimum restoration time and cost, and (4) the final PUS adaptive scheme preferred a light-asset strategy and was applied to the Shenzhen PUS. The PUS-ARAF provides adaptive schemes and local-adaptive life-cycle resilience strategies for PUSs.

A practical biaxial time-dependent material model of PVDF-coated polyester fabrics for structural applications

The utilization of air-supported fabric structures as formwork to construct concrete shells has attracted increasing attention in recent decades. An example of such an airform is the air-supported structure at Dahaize, which consists of a cylindrical part and a hemispherical part, and is 66 m in diameter and 65 m in height. The precise forming analysis of large-span air-supported structures requires the use of a reasonable material model that considers the biaxial stress condition and the creep behavior of the fabric. In this paper, a practical approach to modeling the biaxial time-dependent material behavior of composite fabrics is proposed based on the uniaxial linear viscoelastic theory and the plane stress orthotropic assumption. The multi-Kelvin physical model is developed to the two-dimensional form for the simulation of biaxial creep compliances. Biaxial tensile and biaxial creep tests are conducted on PVDF-coated polyester fabrics to calibrate the material parameters. The experimental stress conditions were determined according to the pre-estimated actual membrane stress distribution. The established material model is employed for the forming analysis of the Dahaize airform under conditions of varying creep times. The simulation results agree well with the on-site measured data, and this validates the accuracy and efficiency of the proposed material model.

Membrane structures: application experience and development prospects

Introduction. At present, studying an increase in the applicability of steel structures in all segments of the construction industry, particularly in residential construction, is relevant. Membrane systems are high-tech and economical structures. The behavior of large-span membrane structures is studied in great detail in practice. However, membranes, combined with medium and small spans, remain understudied.
 
 Materials and methods. Findings of basic theoretical, experimental and numerical studies of membrane systems, used in structural analysis and design, are provided. An advanced membrane slab design, designated for metal-framed multistory residential buildings, is described. Its flat support contour is rectangular in plan; it has a membrane and a monolithic concrete slab over it.
 
 Results. Lira-SAPR software package was used to conduct numerical studies of the membrane slab. The studies took account of its structural, geometrical and physical nonlinearity, and the results were compared with an experimental study. The distribution of forces in its support contour is typical for rectangular membrane structures with positive curvature shells.
 
 Conclusions. Numerical analysis of a full-scale structure and a tested model having a monolithic reinforced concrete slab on the membrane proved the long-term benefits of this structure. The results of numerical analysis demonstrate the qualitative convergence with the experimental data. The variable thickness of the slab resting on the membrane, collaboration of the slab, the membrane and the support contour, the physical nonlinearity of the system elements and, above all, the reinforced concrete slab must be taken into account to reduce the qualitative discrepancy between numerical and experimental results.

Performance evaluation of a nonlinear energy sink with quasi-zero stiffness property for vertical vibration control

The advantages of nonlinear energy sink (NES) have been proven to effectively reduce vibrations in the horizontal direction. The application of NES devices to suppress vertical vibration is still at an early stage. In this study, a new type of NES that works in the vertical direction, where disc springs and viscous dampers are utilized to connect an additional mass with the primary structure, is proposed. The NES device can provide a cubic restoring force characterized by the quasi-zero stiffness (QZS) property. Initially, the equations of motion of the primary structure supplemented with NES were established. Then, the force and displacement transmissibility curves were obtained via the steady-state analysis for the NES-controlled, tuned mass damper (TMD)-controlled, and uncontrolled systems. Analytical results revealed that the targeted energy transfer (TET) property of the NES can absorb the kinetic energy within the operating range without amplifying the response in the lower and higher frequency ranges. In contrast, TMD is more efficient within the operating range. Finally, a practical large-span floor structure was adopted to compare the operating performance of NES and TMD. External vibration includes track-induced vibration, vertical earthquake, and human-induced vibration. Numerical results show that the NES performs better than traditional TMD in controlling the vertical response. Moreover, the addition of a NES device will not potentially amplify the response on some occasions.