Large-span Structures Research Articles

Experimental study on static temperature field effect on standing seam metal roof system

Large-span roof structure is widely used in important landmark buildings. This paper presents the experimental investigations of the deformation and stress distribution of standing seam metal roof system (SSMR) under the condition of a uniform temperature field. The experimental results show that with the increase of temperature, the stresses of slab rib, support, bottom and surface of the roof slab increase gradually, in which the maximum stress growth rates are 1.77, 0.87, 0.64, and 1.68, respectively. The minimum stress increase appears at the slab bottom, while the maximum stress increase with a value of 83.7% of yield strength appears at the slab rib. With the enhancement of the constraint boundary, the stress of the two specimens gradually increases. In particular, the stresses increased the most under fixed at both ends constraints. The stresses show significantly different values in different positions of the roof slab. Both the horizontal and vertical displacement of the roof slab increased with the temperature. And the maximum horizontal displacement of the roof slab is respectively 14.85 mm and 20.42 mm (free one end), in which maximum vertical displacement is 2.34 mm and 6.11 mm, respectively (fix two ends).

Application of Cast Steel Joint in large-Span Steel Structure

Cast steel node is a new type of structure joint developed with the application of large-span steel structure. The stress distribution is discussed of cast steel nodes under three-dimension load by FEM, in the space grid structure of a hangar. By the measurement, the stress on the surface of the cast steel node under the design load is obtained. Combined with the test on-the-spot and computation, the result proves FEM result.

Investigation of the volumetric fractal structure shaping

On the basis of a specially developed algorithm, shaping of the fractal structures, the formation of which is regulated by the power index of the fractal, has been carried out. A sphere and an ellipsoid were used as the basic shapes. The formation analysis has made it possible to determine the characteristic principles of the fractal structure growth. The performed numerical experiment with respect to volumetric fractal structures of power 8 made it possible to determine the spectrum of frequencies and forms of natural oscillations. The offered objects of fractal architecture are analogs of unique high-rise and large-span buildings and structures. The application of the fractal shaping paradigm in combination with digital technologies and innovative materials will make it possible to create completely new objects of architecture.

The Cartis Form for the Seismic Vulnerability Assessment of Timber Large-Span Structures

Italy is located in a very active seismic zone, and many earthquakes have marked the country, some of them in the recent past. In order to take adequate measures of seismic prevention and protection, in the last decades, the Italian Civil Protection Department (DPC) initiated a survey and introduced a specific form for the quick and/or post-seismic assessment of buildings. This is useful to obtain statistics on the types of structures and their vulnerability and a judgement on the damage, leading to a decision about the possibility of reuse and/or the level of retrofitting to be applied. Those activities have been developed since the beginning of 2000. This task is currently carried out by the Italian DPC-ReLUIS project research, line WP2 on the inventory of building structures, setting up the CARTIS form for any structural type, like masonry, reinforced concrete, precast concrete, steel, and timber structures, the latter being mainly related to large span buildings, extensively used in Italy. In this context, the paper presents the first draft of the CARTIS form for large span timber structures that provides a general description for typical structural schemes, through the singular points commonly considered as seismic structural vulnerabilities. Moreover, the statistics on timber large span structures based on a sample of 10 buildings is presented.

RETRACTED: Prefabricated construction process and unloading monitoring of space steel grid cassettle structure multi-storey large-span gymnasium

The gymnasium of Fule International School in Mianyang, Sichuan are multi-storey large-span buildings with a maximum span of 36 m and use a new system-steel grid cassettle structure. In this paper, the structure form, prefabricated construction method and support unloading process of the gymnasium are introduced in detail. To ensure smooth construction unloading, the deflection deformation of the large span floor and the field splicing node are monitored. Results show that the prefabricated construction method of the Mianyang Fule International School Gymnasium and the steel column-scaffold combination support system are affordable. After unloading, the floor has the traits of plates and relatively greater rigid reserve. Thus, it is applicable for large-span and high-load floor structure. The stress in the splicing node in the inflection point (L/2, L is the size of the grid) is relatively small, the bolt and the shearing-resistance plate have no slump, and the field splicing node is safe and reliable. The findings provide a certain reference value for the research and innovation in the process of assembly construction of multi-storey and large-span building.

ИССЛЕДОВАНИЕ ТОЧНОСТИ ПОСТРОЕНИЯ МОДЕЛЕЙ ПО АЛГОРИТМУ SIFT ДЛЯ БОЛЬШЕПРОЛЕТНЫХ СООРУЖЕНИЙ

The article considers the accuracy of floor models creation in large span structures with the use of unmanned aerial vehicles for the purpose of determining their deformations. There were performed 4 aero shootings of Water Sports Palace in Dushambe, which were processed by SIFT algorithm. Syn-chronically with the UAV shooting there was performed the measurements on deformation marks within the frames of geodetic monitoring. There was performed the statistical analysis of models accu-racy by method of interpolation of spherical function, which showed that 80% of points has devia-tions less than 30 mm, and the rest 20% has deviations up to 80 mm. The use of collocation method for smoothing optimal filtering allowed to decrease the differences between settlement surfaces ob-tained by geodetic measurement and UAV shooting up to 26mm., which is 10 % of acceptable devia-tions of this object. It was found out that there is a necessity of further investigations of SIFT algo-rithm and filtering its results for the purpose of increasing the accuracy of object’s models.

Bamboo as a sustainable material in the construction industry: An overview

Abstract India is the second-biggest producer of bamboo worldwide. The increased dependency on conventional construction materials is held responsible for the degradation of the environment and reduced wood resources, which has led to thought on using bamboo as a substitute for wood and steel. Bamboo is perceived as a sustainable, quickly developing, and crude economic material. The investigation endeavors to legitimize selecting bamboo as an appropriate material for efficient and judicious development and evaluating the literature on how it could be utilized in the construction industry. Bamboo as a composite material can be used for various interior and exterior purposes in buildings like foundation, flyovers, dwellings, multistory buildings, large span structures, and interiors of airports, recreational buildings.

Large-span structures and architectural form

The article analyzes: actual problems of architecture and construction of large-span buildings. The experience of building a stadium in Tashkent is being studied. An overview of the positive qualities of the proposed design solutions from a technological and economic point of view is given. Planar structures include those in which each load-bearing element of the coating operates only in its vertical plane independently of other load-bearing elements

Seismic response of large-span spatial structures under multi-support and multidimensional excitations including rotational components

To achieve rational and precise seismic response predictions of large span spatial structures (LSSSs), the inherent non-uniformity and multidimensionality characteristics of earthquake ground motions should be properly taken into consideration. However, due to the limitations of available earthquake stations to record seismic rotational components, the effects of rocking and torsional earthquake components are commonly neglected in the seismic analyses of LSSSs. In this study, a newly developed method to extract the rocking and torsion components at any point along the area of a deployed dense array from the translational earthquake recordings is applied to obtain the rotational seismic inputs for a LSSS. The numerical model of an actual LSSS, the Dalian International Conference Center (DICC), is developed to study the influences of multi-support and multidimensional excitations on the seismic responses of LSSSs. The numerical results reveal that the non-uniformity and multidimensionality of ground motion input can considerably affect the dynamic response of the DICC. The specific degree of influence on the overall and local structural displacements, deformations and forces are comprehensively investigated and discussed.

The influence of human motion state on human-structure interaction

Under pedestrian load, significant vibration and comfort problems are easy to arise for large-span low-frequency structures so that human-structure interaction should be considered in the design. However, different human motion states have different human modal parameters, which makes the design more difficult. The Spring-Mass-Damper (SMD) model is used to conduct numerical simulation experiments on 6 box beams with different fundamental frequencies in 4 different human motion states, based on which the dynamic characteristics of the structure under 30 working conditions are compared and analyzed. It is recommended to use the modal parameters of the standing human body in the vibration comfort design, and use the modal parameters of the human body at normal walking speed for the design of the low-frequency structure.

Experimental Study on the Novel Interface Bond Behavior between Fiber‐Reinforced Concrete and Common Concrete through 3D‐DIC

A novel method was proposed to improve the bond behavior of new‐to‐old concrete interface, which was beneficial to introduce the fiber‐reinforced concrete only at the old concrete interface. This study investigated the effect of the fiber addition, strength grade of new concrete, interfacial angle, and surface treatment types on the bond behavior in terms of the new‐to‐old concrete through the axial tensile tests. The three‐dimensional digital image correlation technique (3D‐DIC) and scanning electron microscope were adopted to evaluate the variation of specimen surface strain distributions and microstructure of fiber‐reinforced concrete and bond interface between new‐to‐old concrete. The experimental results indicated that interfacial angle and surface treatment type were significantly promoted bond behaviors, while the specimen cooperating with steel fibers had the highest bond strength. Besides, the maximum strain locations obtained from 3D‐DIC method were the same as the location of the specimen failure, which indicated the 3D‐DIC method can be adopted to forecast the structural failure. The microcrack strain located in the major crack was decreased with the development of the major crack. Ample crystals and Ca(OH)2 were generated in the interface between the new‐to‐old concrete to weaken the bond strength. Moreover, this paper provided the mechanics‐driven and machine learning method to predict the bond strength. This study provides a new interface bonding method for the fabricated and large span structure to effectively avoid cracking of new‐to‐old concrete.

МОНИТОРИНГ, МОДЕЛИРОВАНИЕ И АНАЛИЗ ПОВЕДЕНИЯ КОНСТРУКЦИЙ

Information technology and modeling are becoming more widely used, mainly in the design and operation of buildings and structures, and in most cases this is enough for trouble-free operation. Nev-ertheless, there is a category of buildings for which the monitoring of the technical condition should be an integral part of the construction and operation. Unfortunately, the development of these technolo-gies in the Russian Federation is not at level, sufficient for answering questions about the behavior of objects under changing environmental conditions and revealing hidden patterns in monitoring data. Based on analysis of literary sources, the authors reviewed various methods for identifying hidden patterns in geodetic measurement data when monitoring buildings and structures. It is noted that mod-ern analysis methods are based on statistical processing of measurement results and on statistical fore-casting method. However, there are attempts to apply models that take into account object’s design features and temperature regime. This type includes two proposed models, which are used to model three-dimensional coordinates of strain marks in the 3D model and only elevations of marks in the 1–Z model. The article presents the rationale for the simulated geometric elements and properties of the object. The solution of the equations of both models and the analysis of the results and parameters of the model for measurement epochs are shown. The simulation is shown on the example of a real ob-ject, which was monitored by the authors in 2015–2016.The authors believe that the monitoring of large-span structures and the search for patterns of their behavior should be an integral part of the in-formation system for such structures.

Systematic monitoring of the deformed state of long-length reinforced concrete structures with an assessment of their reliability

The article shows the method of systematic monitoring of the stress-strain state of reinforced concrete structures covering one of the operated public railway stations. The description of large-span structures of the building, their defects and damages acquired during the operation of the building is given. The article describes the methodology and methods used for long-term, more than 2 years, continuous monitoring of the deformed state of coating structures in operation. The most damaged structures are examined in detail with the help of installed devices to obtain accurate data. The features of measurements in different periods of time and time of year are described. Based on the results of the obtained measurements of the stress-strain state of the building coating structures, the possibility of their further operation is predicted, taking into account the defects and damages found during the survey.

Large-span structures in diploma projects of students architects of RUDN University

At present, there is a renewed interest in the design and application of wall structures in architecture and construction. With the advent of modern computers, refined methods for calculating shells, new building materials, the development of differential geometry and the rapid growth of numerical methods of calculation, it became possible to create architectural masterpieces from shells of canonical and non-canonical forms, which can be the hallmark of a city or country. This emerging trend among young Russian and foreign specialists inspires optimism among scientists who are researching thin-walled shells. The article considers some results of the work of the Department of Civil Engineering of the Engineering Academy of the Peoples Friendship University of Russia on attracting students to architectural design and involving undergraduates in researches on architecture, the theory of thin-walled spatial structures and their application in construction and architecture. The publications of students in this field are presented.

Accounting for geometric nonlinearity in finite element strength calculations of thin-walled shell-type structures

Relevance. Currently, in connection with the wider spread of large-span thinwalled structures such as shells, an urgent issue is the development of computational algorithms for the strength calculation of such objects in a geometrically nonlinear formulation. Despite a significant number of publications on this issue, a rather important aspect remains the need to improve finite element models of such shells that would combine the relative simplicity of the resolving equations, allowance for shear deformations, compactness of the stiffness matrix being formed, the facilitated possibility of modeling and changing boundary conditions and etc. The aim of the work is to develop a finite element algorithm for calculating a thin shell with allowance for shear deformations in a geometrically nonlinear formulation using a finite element with a limited number of variable nodal parameters. Methods. As research tools, the numerical finite element method was chosen. The basic geometric relations between the increment of deformations and the increment of the components of the displacement vector and the increment of the components of the normal vector angle are obtained in two versions of the normal angle of the reference. The stiffness matrix and the column of nodal forces of the quadrangular finite element at the loading step were obtained by minimizing the Lagrange functional. Results. On the example of calculating a cylindrical panel rigidly clamped at the edges under the action of a concentrated force, the efficiency of the developed algorithm was shown in a geometrically nonlinear setting, taking into account the transverse shear strain.

Non-uniform temperature field and effects of large-span spatial truss structure under construction: Field monitoring and numerical analysis

The large-span spatial truss structure under construction can produce significant non-uniform temperature effect due to strong solar radiation, and it directly affects the quality of structural closure and even leads to potential safety hazards. In order to study the non-uniform temperature field, the steel roof of Xi'an Silk Road International Convention and Exhibition Center under construction was selected as the studied structure, the real-time temperatures of test points and thermal boundary conditions were monitored for 30 days. The numerical simulation method of temperature field of spatial truss structure was established considering real-time shadow effect, which can be effectively analyzed by the proposed shadow analysis algorithm. During monitoring period, the structural temperature field under strong solar radiation is significantly non-uniform with maximum temperature difference between test points of 15.6℃, and the maximum temperature rise of test point compared with atmospheric temperature is 16.9℃. By comparison with test results, the accuracy of numerical method is verified, and the daily root mean square of error rates for all monitored members is lower than 6.5% during the monitoring period. Through the analysis of test and simulation results, the non-uniform features of temperature field of large-span spatial truss structure was studied. In addition, the temperature effect was calculated for different healing times considering non-uniform temperature field of large-span spatial truss structure under construction. Then some construction suggestions for healing time were also given. The research method and conclusions of this paper can provide valuable references for thermal design, monitoring and control of large-span spatial truss structure.

Research Overview on Numerical Simulation of The Dismantling Process of Large-span Steel Structural Roof

The dismantling of large-span steel roof is a complex evolutionary process involving redistribution of internal force. In order to ensure conformity of the structural internal forces to the design, safety and reliability during the demolition, it is necessary to make accurate simulation analysis of the dismantling process to determine a reasonable dismantling plan. With a review of the simulation methods adopted in the dismantling process of large-span steel structure and analysis of the relevant research results, this paper elaborates on advantages, disadvantages and adaptability of each method, which can serve as a basis for the study of roof dismantling.

An Analytical Research about Parameter Influence on Large-Scale Anchorage Region with Multiple CFRP Cables

This study investigates the mechanical properties of carbon fiber reinforced polymer (CFRP) cable at the anchoring region where arrange the adhesive material with different mediums aiming at reducing the high stress concentration. The 3D finite element (FE) model was established based on cable force of 100t and 1000t, and its accuracy was verified by experimental results. The effects of geometrical dimensions and mediums stiffness on anchoring capacity of the cable was studied. The results show that the proposed anchorage gets high anchoring efficiency. The gradient variation of the stiffness of the adhesive material can effectively reduce the stress crest of the cable at the anchorage region. The distributions of the radial and shear stress of the cable at the anchorage region become comparatively flat with the increase in the number of segments. The variation stiffness and length ratio have the main influence on the stress of the cable in three orientations. Friction coefficient and internal taper have the secondary effects on the radial stress and the axial displacement. Anchor length and thickness of adhesive material only affect the radial stress. Anchorage design should primarily focus on the stiffness and length ratio of the adhesive material. The anchoring method proposed in this paper is helpful to anchor multi-tendon cables efficiently, and promote the application of high-capacity FRP cables in large-span spatial structure.

Error Caused by Damping Formulating in Multiple Support Excitation Problems

The effect of multiple support excitation is an important issue in studying large-span structures. Researchers have shown that the damping related terms in the equation of motion can induce errors in the analysis. Wrongly modelling the damping matrix can induce false damping forces between the structure and the reference coordinates. In multiple support excitation problems, this error is increased when absolute coordinates are used. In this paper, this part of the error is defined as virtual damping error. The error caused by using Rayleigh damping instead of Modal damping is called damping truncation error. This study focuses on the virtual damping error and the damping truncation error that exist in the modeling methods widely used in multiple support excitation problems, namely, large mass method (LMM), relative motion method (RMM), and absolute displacement method (ADM). A new Rayleigh damping formula is proposed for LMM to prevent virtual damping error. A form of equation of motion derived from the converged LMM was proposed in the authors’ previous work. This equation of motion is proved in this paper to be equivalent to RMM when modal damping and the new Rayleigh damping formula are used. RMM is proved free from the virtual damping error. The influence of multiple support excitation effect on the damping formulating errors is studied by spectral analysis. One simplified spring-mass model and two bridge models are used for numerical simulation. The results from the numerical simulation testify to the conclusions from the spectral analysis.

Rate-dependent mechanical properties and elastic modulus of ETFE foils used in inflated forming of transparency air-inflated cushion membrane structures

ETFE (ethylene tetrafluoroethylene) air-inflated cushion structure has become one of the primary choices for being roofs and facades of large-span structures. Prior to the load bearing stages, it is required to firstly inflate the ETFE cushion envelope to gain the desired initial geometrical height and structural stiffness. This paper thus proposes a combination of analytical, experimental, and numerical methods to evaluate the rate-dependent mechanical properties and elastic modulus of ETFE foils used in the inflated forming processes of ETFE cushion structures. Starting from the typical uniaxial tensile stress-strain curve, the existing geometrical and mathematical method and a new proposed equivalent energy method are utilized to determine the mechanical parameters of ETFE foils together. Subsequently, a series of uniaxial tensile tests at the strain rates of 0.1–1000%/min were conducted on the dumbbell specimens of ETFE foils in order to acquire the yield strength and strain, the tangent, secant and equivalent moduli. Such results can be used to uncover the rate-dependent mechanical properties of ETFE foils and analyze the structural behaviors of ETFE cushions. Finally, numerical simulations of inflated forming were completed on four flat-patterning ETFE cushion models with considering the nonlinear material model of Perzyna model and the linear material properties of tangent, secant and equivalent moduli, respectively. As such, this research provides a new opportunity to elucidate the most appropriate choice of elastic moduli in design, analysis and optimization of ETFE membrane structures.