Large-span Structures Research Articles

Geometric design of rotary retractable plate structures based on parallelogram closed-loop chain linkages

For large-span retractable roof structures, the mechanism should be simple and efficient for the convenience of motion control. The kinematic characteristics of parallelogram closed-loop chain linkages (PCCL) show that a set of the angulated beams of PCCL rotates around the fixed points, which is suitable for retractable structures. This paper focuses on the geometrical design of the rotary retractable plate structures (RRPS), which evolves from PCCL by replacing the rotation angulated beams with cover plates. Each plate of RRPS has a fixed support and all the plates rotate simultaneously with a single DOF. The fixed points used as supports for cover plates to improve the stability and simplify the motion control of the system restrict the open area of the RRPS. By adjusting the contact boundaries of the cover plates, an optimisation method is proposed to increase the open area of the RRPS after fully deployed. The design approach is successfully extended to both symmetrical and asymmetrical RRPS. An example is carried out to demonstrate the feasibility of the approach and a simple physical model is manufactured to validate the design result in the example.

Optimal design of a large-span spatial structure based on dynamic elastic-plastic analysis

With the expansion of the urban areas and the rapid growth of the urban population, the disposal of large amounts of domestic waste has become a problem faced by large cities. To solve this problem, many MSW incineration power plants have been continuously built. As a typical large-span spatial structure of waste incineration power plant, how to achieve economic, beautiful, and environmentally friendly design goals under the premise of meeting the requirements of the production process is an important problem currently facing. In this paper, a structural design optimization method based on damage index is proposed. Taking a large-span mixed structure of a MSW incineration power plant as an example, the paper firstly uses the dynamic elastic-plastic time history analysis method to evaluate its seismic performance, and then optimizes the structure according to the damage degree of the structure under small and large earthquakes design. The results show that under the premise of meeting the requirements of the code, this method can ensure that the degree of structural damage under the earthquake remains almost unchanged, while significantly reducing the amount of building materials and reducing the cost. At the same time, this method is more direct, simple, and effective than optimization design methods based on experience and internal forces of structural members.

Behaviour of Rectangular Concrete Deep Beams with Hybrid Fibre Reinforced Polymer Reinforcements Considering Web Openings

The use of non-corrosive reinforcements in the place of steel reinforcements has therefore been focused as an alternative to improve the life span of the concrete structures. Fibre Reinforced Polymer (FRP) reinforcements offer many advantages over steel reinforcements including resistance to electrochemical corrosion, high strength to weight ratio and easy in fabrication and electromagnetic insulating properties. Further, the use of hybrid FRP reinforcements, in lieu of conventional steel reinforcements requires better understanding under different parametric conditions. Therefore the present study deals mainly with the behaviour of Concrete Deep beams with and without openings reinforced internally with hybrid type Fibre Reinforced Polymer (FRP) reinforcements under static loading conditions. In structural applications, deep beams are commonly used as large span structures such as transfer girders in buildings, bridges, foundation walls, shear walls and offshore structures. In this study,high strength concrete deep beams are investigated. Among the eight beams, four beams are reinforced internally using conventional reinforcements with and without web opening, four beams are reinforced internally using hybrid FRP reinforcements with and without web openings. Different parameters like, high strength concrete, web opening positions (Top, Middle and Bottom), span sprinkled FRP hybrid reinforcements are considered. Based on this study, static load carrying capacities and their modes of failures of deep beams reinforced internally with FRP hybrid type reinforcements for various web openings positions are compared by finite element modelling using ANSYS software with the existing theories for better under standings. Based on the modelling and theoretical work, final conclusions of the present study are derived.

Development of a Frequency-Adjustable Tuned Mass Damper (FATMD) for Structural Vibration Control

The tuned mass damper (TMD) can be applied to suppress earthquake, wind, and pedestrian- and machine-induced vibration in factory buildings or large span structures. However, the traditional TMD with a fixed frequency will not be able to perform effectively against the frequency variations in multiple hazards. This paper proposed a frequency-adjustable tuned mass damper (FATMD) to solve this limitation of current TMD. The FATMD presented in this paper is composed of a simple assembly consisting of a supported beam with a mass, in which the frequency of the FATMD is changed by adjusting the span of the beam. The kinematic equation of a single degree of freedom (SDOF) structure installed with an FATMD is established to analyze the effect of the damping ratio, mass ratio, and stiffness on the vibration damping. The fundamental frequency of the FATMD at different spans is verified by simulation and experiments. Forced vibration experiments with different excitation frequencies are also conducted to verify the performance of the FATMD. The results show that the proposed FATMD can effectively suppress the vertical vibration of structures at different excitation frequencies, including frequencies at a range higher than what a traditional TMD may not be able to suppress. Additionally, the proposed FATMD is applied to a long-span pedestrian bridge which vibrates frequently due to the walking of pedestrians, the running of escalators, and earthquakes. The numerical results indicate that the FATMD can effectively reduce the vertical vibration of the pedestrian bridge under the excitations of pedestrians, escalators, and earthquakes.

Size Effect on Nominal Strength of Lightweight and Normal Concrete-Filled Steel Tube Columns under Axial Compression: Mesoscale Simulations

With the devolvement of large-span structures and super high-rise buildings, lightweight aggregate concrete (LWAC) materials have been widely utilized. The main content of this work is to explore the failure and size effect of lightweight aggregate concrete-filled steel tube (LWACFST) columns under uniaxial compression. A three-dimesnional mesoscale simulation approach considering concrete heterogeneity was developed, in which the ideal bond was assumed between the steel tube and inner concretes. The failure of geometrically similar square and circular LWACFST/CFST columns under axial compression having different structural sizes and transverse constraints was modeled and explored. The size effect on the nominal compressive strength of the columns was examined. The influences of aggregate type, column cross-sectional type, and constraint effect generated by the steel tube on the size effect in axial compressive failure are also investigated. The results indicate that an obvious size effect in axial-compressive failure can be found for both LWACFST and CFST columns. With the increase of the confinement degree of steel tube, the size effect on nominal compressive strength would be weakened. The LWACFST columns exhibits a more obvious size effect than the CFST columns. Moreover, the size effect on the compressive strength of the circular columns is obviously weaker than the effect on square columns. Finally, considering the quantitative influence of confinement coefficient, a novel size effect law (SEL) for quantitatively describing the size effect in axial-loaded CFST columns was proposed. The accuracy and reasonability of the proposed SEL was verified by the available test data.

Topology optimization and shape design method for large-span tensegrity structures with reciprocal struts

Tensegrity is a kind of efficient structural system that is composed of continuous cables in tension and discontinuous struts in compression. Although the studies on tensegrity have been carried out by many researchers, there are few methods for assembling large-span tensegrity by multiple units. Inspired by the similarities between reciprocal units and tensegrity units, we present a novel method for designing large-span tensegrity structures with reciprocal struts, which is a kind of new tensegrity structural system that can cover a large area, while the rule of discontinuous struts is followed strictly. The proposed design method includes assembly, topology optimization, and shape design. The prototype; i.e., initial topology, of the tensegrity is generated from reciprocal struts. A topology optimization method using ground structure approach is proposed to remove the redundant cables from the initial topology. A shape design method using fictitious stiffness parameters is proposed to satisfy the architectural shape demand. The form-finding problem, which is to find the self-equilibrium shape in the topology optimization as well as shape design processes, is solved by using the non-rigid-body motion analysis method. Numerical examples demonstrate the effectiveness and applicability of the proposed method.

Corrosion Behavior of Different Cables of Large-Span Building Structures in Different Environments

AbstractSpiral strands, galvanized steel wires, galvanized semiparallel wire strands, and steel tie rods in large-span building structures are inevitably corroded due to long-term exposure to corro...

Axial force identification of space grid structural members using particle swarm optimization method

Space grid structures are popularly used in large-span civil structures. Identification of the axial internal forces and boundary conditions of the space grid structural members is very important. However, in the engineering practice, the boundary conditions of such members are not ideally rigid or pinned. They are sometimes semi-rigid conditions. Besides, direct measurements of the axial forces and the boundary rigidities of in-situ space grid structural members are difficult to make. Therefore, in this study, a Particle Swarm Optimization (PSO) algorithm-based axial force and boundary rigidity identification method is proposed for space grid structural members using multi-order natural frequencies, which can be easily obtained from in-situ tests. The theoretical background of the proposed method is discussed in detail, including the coupling relationship between the axial force and natural frequency and the PSO algorithm. The applicability and accuracy of the proposed method are validated through experimental tests and comparative analyses.

The influence of the structural vibrations’ logarithmic decrement on its stability in the event of vortex excitation

The article considers the influence of the structural vibrations’ logarithmic decrement on its stability in the event of vortex excitation. The relevance of the topic is due to the widespread problem of vortex excitation in the construction and operation of large-span bridge structures. The introduction presents the characteristic features of vortex excitation as a phenomenon of aerodynamic instability. In the second section, the research method is given, the research object is described, and the considered variants of the logarithmic decrement of the beam span’s investigated construction vibrations are given. The third section presents the experimental studies’ results at the Unique Scientific Installation, Big Research Gradient Wind Tunnel, NRU MGSU in graphical form. The conclusions about increasing the structural stability with increasing values of the vibrations’ logarithmic decrement are drawn.

Structural analysis and construction quality assessment of a free-form ice composite shell

The large-span ice composite shell structure constructed by inflatable formwork and cellulose-water mixture spraying method brings a new aesthetic activity to the conventional ice and snow buildings. How to ensure the structural safety of large-span ice shells and satisfy the serviceability in the operation stage has become an urgent problem for structural engineers. Based on the Koi-fish ice shell structure constructed in winter at Harbin Ice-Snow World, China, exhaustive structural investigations on the behaviour of the ice composite shell under multiple load conditions are conducted. Subsequently, the construction quality of the ice shell after completion is discussed and evaluated. The results show that temperature action is the main factor affecting the structural safety of the ice shell. Construction assessment results show that the practical ice shell structure can satisfy the design safety requirements.

Non-uniform temperature field and effect on construction of large-span steel structures

For large-span steel structures, the construction process is important, and it needs to be analyzed in the design stage to provide guidance on construction control. In terms of the complex load effects that affect the forced state of a structure, the time-dependent temperature field is one of the most important effects, but it is always not considered. In this paper, a new method for simulating the non-uniform and time-varying temperature field of large-span steel structures is proposed. This method calculates the shading effect and the actual solar radiation absorbed by tubular members. Moreover, the proposed method is combined with the construction process simulation method to consider the temperature effect in the construction accurately. After that, the steel roof of the terminal building of the Beijing Daxing International Airport is taken as an application case. The numerical simulation of the temperature field and the construction process that considers the temperature effect is performed using ANSYS. The accuracy of the simulation results is verified with the data of on-site monitoring. The results show that the temperature field of the large-span steel structure has obvious non-uniformity and time-varying characteristics, and the sunlight shadow should not be ignored. The cumulative temperature effect generated during the construction process is significant. The proposed method is recommended for the design stage of large-span steel structures.

Tension analysis of bolted sleeve connection between pultruded GFRP tube and steel member considering adhesion

Pultruded Glass fibre reinforced polymer (GFRP)-steel hybrid structures have become increasingly popular in civil infrastructures. However, the connection between GFRP and steel members is one of the key issues limiting the development of the innovative structure. This paper presents tensile capacity of bolted sleeve connection between GFRP and steel members. With consideration of the pre-loaded bolt effect, the appropriate fastening torque was proposed by finite element investigation. The adhesive effect was also considered and investigated by cohesive zone method. The bolted sleeve connection provides a good solution for the tubular and large-span structures.

Shaking table test on 1000 kV UHV transmission tower-line coupling system

Ultra high voltage (UHV) transmission tower-line coupling system consists of transmission lines (conductors and ground wires) supported by a series of lattice towers. However, in the current seismic design code, the transmission lines are just simplified as additional mass while the effect of nonlinear vibration of transmission lines on the seismic responses of transmission towers is not taken into consideration. To analyze the influence of the ignorance of the coupling effect between towers and transmission lines, two types of model structures, i.e. tower-line coupling system model and single tower model with lumped masses, should be tested for comparison. But normal reduced-scale model design method cannot complete the shaking table test by a uniform geometric similarity ratio for the coupling system in the limit of table size, hence this paper proposed to rescale the geometric similarity ratio for the model design of transmission lines and meanwhile satisfied the requirement in dynamic properties similitude and inertia force similitude separately, which successfully solved the problem that the span of transmission lines in the test was too large to fit within the shaking table. This method may offer reference to experimental studies for other large-span structures and the experimental results show that the nonlinear vibration of transmission lines plays a role as seismic reduction by dissipating some seismic energy to towers under earthquake.

Building performance monitoring and analysis of a large-span aerogel-membrane airport terminal

The utilization of large-span membrane structures as airport terminals has attracted considerable attention due to excellent building aesthetics, reasonable structural behavior and multi-functional applications. Safety and serviceability of such structures are strongly related to temperature effects in comparisons with steel/aluminum structures since temperature can accelerate material creep strain and deteriorate structural behavior. One alternative method to reduce temperature effects is the incorporation of aerogel materials between two membrane layers. This paper thus focuses on temperature effects of a newly-built aerogel-membrane airport terminal and utilizes experimental results to assess corresponding building performance.The aerogel-membrane airport terminal is designed with wind loads of 0.4 kN/m2, snow loads of 0.7 kN/m2 and earthquake magnitude of 7 in accordance with the requirements of building standards and codes. The aerogel-membrane roof is composed of an outer membrane layer and an inner composite membrane layer integrated aerogel material mats. The surface temperature gradients with respect to outer membrane layer, inner membrane layer and indoor air are identified and quantified. The quantified temperature can be used for thermal-structural analysis and building performance improvement in the design process. The calculated thermal performance indexes mean a hot environment in the inner airport space. A further comparative analysis with a two-layer membrane stadium demonstrates that aerogel materials can reduce temperature effects significantly and ensure structural safety. Therefore, the effects of aerogel on the improvement of structural behavior and building performance of a new membrane airport have been validated with experimental results and comparisons.

Expression of Glued Laminated Timber in Long Spans Structures Associated with its Natural Origin

Abstract The article presents an analysis of the possibilities of shaping long - span structures using the expressive force of glued laminated timber related to its natural origin. Changes that arose in the 20th century and at the beginning of the 21st century under the influence of new technological possibilities in the field of woodworking, as well as radical changes in the doctrine of environmental protection, also changed the position of timber as an innovative construction material. Recent developments are considered groundbreaking. Timber is used both in large span structures as well as for the construction of multi-storey buildings, which opens the door for shaping new architectural forms. The principles of girder modelling and features related to timber symbolism were presented.

Superposition Technology of Complex Giant Reinforced Concrete Beams

Superposition technology construction is widely used in Large-span structures, super high-rise structures and large drop concrete structures. Based on the construction process of reinforced concrete for deep foundation pit engineering in Changsha Ice and Snow World, Superposition technology and support design of large section concrete structures are discussed. ABAQUS finite element analysis was used to obtain the pouring process. It provides the technical foundation for the future design and construction of complex giant reinforced concrete structures.

Stability of cable-supported spherical reticulated shell with tension members

The suspendome has been widely employed in large-span space structures in recent years, and it has stronger structural stiffness and higher load-carrying capacity than single-layer spherical reticulated shell. In general, it is negligible for enhancement of load-carrying capacity to integrate cables and struts into the inner ring of reticulated shell. Based on the suspendome structure, a new hybrid space structure system, namely, cable-supported reticulated shell with tension member, is proposed in this study. To elucidate and verify its feasibility, the buckling mode and buckling form are obtained by the eigenvalue buckling analysis and nonlinear buckling analysis using ANSYS package, respectively. Furthermore, to determine the optimal structural form, this article investigates the effect of the main ribbed strut length, the initial geometric imperfection, asymmetric load, pretension in cables, and the material nonlinearity on its stability. The result shows that the proposed new structural system is of high load-carrying capacity. Tension member integrated to cable-supported reticulated shell can effectively improve the overall stiffness and greatly reduce the deformation of spherical reticulated shell. The plastic failure shape occurs with the similar pattern. The instable region mainly occurs on the main ribs with tension members, and each main rib only has one local failure dimple. The load-carrying capacity is remarkably affected by the asymmetric load, the initial geometric imperfection, and material nonlinearity. Based on the parametric analyses, Type C is the optimal choice, that is, appending cables and struts to the outermost ring of single-layer spherical reticulated shell, and arranging out-of-plane tension members under the four main ribs.

КОНСТРУКТИВНЫЕ ИЗМЕНЕНИЯ В АРХИТЕКТУРЕ САНКТ-ПЕТЕРБУРГА ПЕРВОЙ ПОЛОВИНЫ XIX ВЕКА

The article discusses the changes that have occurred in the architectural and construction practice of Russia in the first half of the XIX century. New building materials: cast iron, iron, facing bricks, hydraulic binders are tested and introduced. Beam system is gradually replacing the vaulted-beam structural system of residential buildings. During this period, the first examples of the supporting frame in a building made of cast-iron columns appeared. This fundamentally changed the possibilities of architecture in the following decades. In the middle of the 19th century, wooden farms were replaced with iron, more durable and fireproof. The creation of complex large-span structures from new materials has led to the development of methods for their calculation, the emergence of a new specialty in building design - structural engineers. Strengthening the brickwork of the walls, reinforcing it with iron elements, made it possible to increase the height of mass residential buildings to 4–5 floors. Typical for the seventeenth century, the stairs on the brick vaults gradually begin to do on the metal braids. New facade elements, such as balconies, loggias, peaks, bay windows, began to be widely used. Lattices and brackets of balconies, roof fencing, canopies over entrances, window lattices were made of cast iron. The use of metal jumpers made it possible to expand the openings of the first floor of buildings, turning windows into shop windows. The introduction of metal structures in construction practice gradually changed the architecture of the facades, which ultimately led to a change in the appearance of buildings and architectural and artistic style. The article provides generalizations and conclusions on the research conducted by the author, based on extensive bibliographic and archival materials, building survey documents, design and restoration drawings, made by design workshops in St. Petersburg.

Experimental study on wind force coefficient of a truss arch tower with multiple skewbacks

A truss arch tower is a large-span arch structure with multiple skewbacks. This tower is made of a large number of members with unique form, and contains more than five kinds of geometric features. The wind forces and the corresponding wind effects on the truss arch tower are notably complicated. In this study, wind tunnel tests were conducted to evaluate the wind forces on the steel latticed structure mentioned above using the high-frequency base balance technique. Four segmental models, including one arch foot of main truss, two arch feet of sub-truss, and one arch crown of main truss were tested in nominally smooth flow. The drag forces were measured and compared with several existing codes, including the British, American, and Chinese codes. The incidence angle effects and the interference effects on the drag coefficient were analyzed. The testing results showed that the direction of the wind forces has a marked effect on the whole truss tower. The solidity ratio and layout of the segmental models, including the cross-section and the centerline of the members, have critical effects on the drag forces.

Damaged ceiling detection and localization in large-span structures using convolutional neural networks

To overcome the limitations of human-based visual onsite inspections, a vision-based method using deep learning with a convolutional neural network (CNN) is proposed to detect and localize the damaged ceiling of large-span structures. The designed CNN model is trained, validated, and tested using 1953 ceiling images, and a prediction accuracy of 86.22% is obtained. The results of a comparative study demonstrate that the saliency map method can accurately localize regions with damaged ceiling and demonstrate the outline shape of the damaged regions. The features visualization using a saliency map reveals that the CNN model is capable of recognizing the overall layout of the inside of a building through images of the intact part of the building and regions with damaged ceiling through images of damaged areas, although, the non-ceiling regions, particularly isolated regions with regular shapes, have a significant influence on the damage prediction probability. Non-ceiling regions and the area ratio are two important factors influencing the prediction accuracy of the CNN model. A statistical analysis indicates that a prediction accuracy of greater than 98% can be obtained in the case of no non-ceiling regions and an area ratio ranging from 20% to 30%. Therefore, photographic method is proposed for capturing ceiling images and improving the prediction accuracy of the CNN model.