Large-span Roof Structure Research Articles

APPLICATION OF BASIC PRINCIPLES OF BUILDINGS AND STRUCTURES PROTECTION IN THE CONDITIONS OF POSSIBLE SHELLINGS BY THE EXAMPLE OF REINFORCED CONCRETE LONG-SPAN TRUSS

For developing recommendations for the protection of buildings and structures under the threat of potential shelling, a summary and analysis of the scientific and technical work conducted by the SRIBP has been carried out, taking into account the principles and guidelines outlined in current regulations. The proposed recommendations can be used to develop national building codes and standards for the protection of building objects from potential shelling. Three groups of objects have been identified based on the risk of shelling, depending on the level of risk: highest risk (Group 1), increased risk (Group 2), and moderate risk (Group 3). The proposed approaches (with their advantages and disadvantages) for protecting construction objects from shelling include: direct calculation for shelling impacts, considering the most likely and unfavorable scenarios; application of direct structural requirements that will most likely ensure the overall survivability of the object or structure after being hit during shelling; general reserve of load-bearing capacity, usually by increasing reliability coefficients. Their application has been considered depending on the risk group and the responsibility classes of the construction object. For Group 1, a comprehensive set of all the mentioned measures is applied; for Group 2, mandatory minimum structural requirements; for Group 3, there are no specific requirements. As an example, a large-span roof structure of an industrial building from Group 1, which is subject to a damage scenario from a projectile impact, has been considered. During the summary of inspection and research results conducted by SRIBP, statistical data on types of large-span reinforced concrete roof structures of industrial buildings have been collected. It has been established that 24-meter-long reinforced concrete trusses are significantly widespread, and they have been selected for consideration as an example of applying the proposed protection approaches. Based on the summary of inspection results, a damage scenario for the truss has been defined, which involves the complete or partial loss of one of the elements (diagonal and vertical web members) due to a projectile impact on the roof structure. Approaches to developing protection for load-bearing structures, adapted for the 24-meter reinforced concrete truss in question, which has sustained element loss after impact, are presented.

Enhancing the aerodynamic performance of large-span roof using a ‘breathable’ optimization tube: A parametric study

In wind engineering community, large-span roofs are widely acknowledged to be wind-sensitive, and oftentimes aerodynamic optimization is needed to enhance its wind-resistance. For such purpose, we proposed a “breathable” aerodynamic optimization tube in this study, the performance of which was experimentally examined via a series of wind tunnel tests. The results showed that, the proposed aerodynamic optimization tube is capable to significantly reducing the wind loads on the large-span roof, the effectiveness of which varies with different tube parameters. On this account, the effect of six key parameters, namely section shape, inlet-outlet angle, hole size, in-out ratio, hole distance and inlet hole length were examined independently. Overall, the outcomes are expected to provide important implications regarding the wind-resistance design of large-span roof structures.

Study on the Wind-induced Interference Effect of a Large-span Roof Structure Building Group

The wind-induced interference effects existing during the construction of a building group were studied in the context of the Zhangjiakou Olympic Sports Center project. Based on CFD numerical simulations, 120 and 96 different working conditions during construction of a swimming pool and speed skating hall were simulated and analyzed respectively, and the numerical simulation results were found to be in high agreement with the wind tunnel test results, which verified the accuracy and feasibility of the numerical simulation. By comparing the wind-induced interference effects of the surrounding buildings on the swimming pool and the speed skating hall during different construction periods, it was found that the swimming pool was more affected by the interference of the surrounding buildings than the speed skating hall, and the wall area was more affected by the interference than the roof area. The wind-induced response of the swimming pool structure during different construction periods was analyzed, and it was found that the interference effect under some working conditions had a greater impact on the structural stress, and it was suggested that the wind interference effect brought about by the construction of the building should not be ignored in such projects.

Determination of Multiple-target Equivalent Static Wind Load of Large-span Roof Structures based on Clustering Analysis Techniques

Spatial structures in modern society exhibit a city’s distinguishing features and show its strength in building technology. Large-span roof structures are mostly seen among spatial structures for various activities. Large-span roof structures are usually sensitive to wind loads due to their lightness in materials and curved geometric appearance. However, spatial structures are generally designed with many structural members, making it challenging to determine adequate load distributions for structural safety analysis. This paper intends to introduce the concept of the multiple-target equivalent static wind loads and to demonstrate how to reduce the heavy computational burden when the structural designer needs to consider multiple loading effects of the target structure. The wind tunnel test of an elliptical-shaped stadium structure with a flat roof is first conducted to show the fundamental aerodynamic characteristics. The methodologies of the background-component wind force based on the load-response-correlation (LRC) method and the resonant-component wind force based on the inertial force method are then introduced for the specification of single-target equivalent static wind loads. Finally, the clustering analysis technique is adopted to explain the concept of the multiple-target equal static wind loads. A decay index is proposed to indicate how the clustering technique improves the specification of equivalent static wind loads.

Multi-hazard resilience assessment framework for prefabricated underground stations with a large-span roof structure

Prefabricated underground stations (PUSs) have been gradually applied as a new approach to urban low-carbon development; however, safe service for the city over the entire PUS life cycle remains a crucial issue. This study therefore investigates the resilience of PUSs with a large-span roof structure in multi-hazard urban environments. A joint vulnerability function is established to represent the PUS physical resilience, and a restorability function is established to represent the local community resilience. The physical resilience and community resilience are integrated to construct a PUS resilience assessment framework (PUS-RAF). The results indicates that: (1) the vulnerability function, experiment and FEA jointly present the PUS assembled joints' contact failure mode; (2) multi-hazard resilience assessment reveals the inherent sensitivity of PUS schemes (3) PUS-RAF predicts a joint scheme highly inclusive of multi-hazard factor; (4) the final PUS scheme accommodates the engineering and community. The PUS-RAF thus provides a practical assessment tool and application value for PUS resilience in multi-hazard environment.

Wind Pressure Field Reconstruction and Prediction of Large-Span Roof Structure with Folded-Plate Type Based on Proper Orthogonal Decomposition

The complex and diverse structural forms make it impossible to define universal shape coefficients for large-span roof structures, which usually need to be obtained by wind tunnel tests. However, the number of test measurement points is limited, which leads to obvious limitations in the study of wind loads on large-span roof structures. Taking a large-span folded-plate roof as an example, based on the wind tunnel pressure test results of the rigid model, the proper orthogonal decomposition (POD) method is used to reconstruct the wind pressure field of the roof using the first several eigenmodes. The wind pressure of several typical characteristic points is predicted based on four different interpolations methods, and the accuracy and feasibility of POD method in reconstruction and prediction of wind pressure field of large-span roof are analyzed and studied from multiple perspectives. The results show that the order of the selected structural eigenmodes has an impact on the reconstruction accuracy of the wind pressure field. The more orders are selected, the closer the wind pressure field reconstruction is to the true value. The reconstruction effect of the wind pressure field based on the POD method is related to the spatial position of the predicted point, and the reconstruction effect of the wind field based on the fluctuating wind pressure is obviously better than the that based on the mean wind pressure. When the POD method is used to predict the wind pressure of an unknown point, different interpolation methods can achieve ideal results. Among them, the bilinear interpolation method has the highest prediction accuracy, and the adjacent point interpolation method and Griddata V4 interpolation method only have certain errors in the low frequency region.

Aerodynamic shape optimization of large-span coal sheds for wind-induced effect mitigation using surrogate models

Large-span coal sheds commonly used in thermal power plants are particularly vulnerable to wind loads, and the aerodynamic performances are largely affected by their external shapes. The search for the best performing shape through an aerodynamic optimization is still of importance for the mitigation of the design wind loads and responses. This study investigated the possibility of using surrogate models combined with genetic algorithm to carry out the aerodynamic shape optimization of large-span roof structures. The approach is applied to tri-centered coal sheds with closed and open gables, respectively. The shape optimization is numerically performed to minimize the vertical displacement of the shed model while subjecting to one normal and two oblique wind directions, 0°, 30° and 45°. The aerodynamic forces acting on coal sheds immersed in turbulent flow are obtained by the CFD simulation with RSM turbulence model, and the results are validated with wind tunnel tests. Kriging model is used to establish a global mapping between design variables and objective function by conducting a set of CFD and structural static response analyses. Results show that the aerodynamic loads and the optimal geometry are sensitive to the selection of gable types and wind directions. The optimal design presents a reasonable performance improvement compared with the near-optimal and original designs. Several compromised designs are finally provided in order to seek a balance between the effects of wind directionality and construction cost.

Coaction of Wind and Rain Effects on Large-Span Hyperbolic Roofs

Rainfall is often accompanied by strong winds. The large-span roof structure has a low height, its surrounding turbulence is high, and the wind speed changes greatly. The effects of coaction of wind and rain on the roofs cannot be ignored. Wind-driven rain (WDR) is an oblique movement phenomenon of raindrops generated by wind flow. Four types of hyperbolic roofs, that is, square, rectangular, circular, and elliptical, are selected as the objective to study the wind-driven rain by CFD simulation. Effects of wind direction, wind speed, and rainfall intensity on the WDR are analyzed. Pressure distribution of four types of hyperbolic roofs under coaction of wind and rain is obtained. The results are compared with those from the wind action only. The roofs are partitioned to obtain the coaction of wind and rain pressure of the four large-span hyperbolic roofs with different shapes under the most unfavorable working conditions. The results show that the average pressure coefficient of the roof surface increases with the increase of wind speed and rainfall intensity. The reference value of the average pressure coefficient of wind-driven rain on the surface of the roof is given, which provides a reference basis for the design of wind-driven rain on similar hyperbolic roofs.

A Study on Nonlinear Dynamic Response of the Large-Span Roof Structure with Suspended Substructure

Nowadays, it is common to see large public buildings, e.g., stadiums, with some equipment or substructure suspended from the center of the roof. These substructures will tend to be larger and heavier the more gear is needed, which may have negative impacts on the dynamic performance of the roof structures. In this paper, to explore the dynamic response of a large-span roof structure with a suspended substructure, a real structure model is simplified into a two-degrees-of-freedom system. The essential consideration of nonlinear vibration is elaborated in the equations of motions. Approximate analytical solutions for free and forced vibrations are derived using perturbation methods, while numerical analysis is carried out to validate the solutions. The ratio of linear to nonlinear amplitude is proposed to represent the nonlinear effect of the primary structure, and the nonlinear effect, varying with structural parameters of frequency ratio, mass ratio, excitation ratio, and external force to the primary structure, is investigated. It is shown that internal resonance occurs when the structural frequency ratio is close to 1:2 and that secondary resonance takes place due to certain external excitations; internal resonance and secondary resonance will magnify the amplitude of the primary structure during vibration. Finally, a case of a designed practical dome with a suspended substructure is studied to verify the outcomes from the above research. According to these findings, some design proposals for this type of structure are provided.

Optimization of steel roof trusses using machine learning-assisted differential evolution

A steel truss is a preferred solution in large-span roof structures due to its good attributes such as lightweight, durability. However, designing steel trusses is a challenging task for engineers due to a large number of design variables. Recently, optimization-based design approaches have demonstrated the great potential to effectively support structural engineers in finding the optimal designs of truss structures. This paper aims to use the AdaBoost-DE algorithm for optimizing steel roof trusses. The AdaBoost-DE employed in this study is a hybrid algorithm in which the AdaBoost classification technique is used to enhance the performance of the Differential Evolution algorithm by skipping unnecessary fitness evaluations during the optimization process. An example of a duo-pitch steel roof truss with a span of 24 meters is carried out. The result shows that the AdaBoost-DE achieves the same optimal design as the original DE algorithm, but reduces the computational cost by approximately 36%.

RESEARCH ON FORCE AND MODAL ANALYSIS OF THE CANTILEVER ROOF MODEL OF A STADIUM

The large-span roof structure is favored by architects and structural engineers all over the world for its novel architectural shape and reasonable structural characteristics. It has been widely used in large public buildings such as sports buildings, memorial buildings and cultural buildings. Based on the structure design of the fourth national college students’ competition winning entries for the model, this paper introduces the stadium upper cantilever roof structure model selection, process design, interface, etc. Using the finite element software ANSYS to analyze the model structure under different load conditions of the static performance, we acquire its natural frequency. The results show that the model meets both the strength and stiffness requirement.

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).

Experimental Study on Mechanical Properties of Small Size Viscoelastic Damper

Long span roofs are very likely to oscillate when subjected to wind load that can lead to structure fatigue and endanger structures safety. Dampers have been used for long time to dissipate wind and earthquake induced energy in structures. This research work aims to present experimental study of small size viscoelastic damper that can be installed in truss of long span roof. Small size viscoelastic dampers that can be used to dissipate wind induced energy in large span roof structure need to be tested to know their performance behavior and mechanical properties at different loading amplitudes and frequencies. A kind of viscoelastic dampers were manufactured and tested under horizontal cyclic loads. Resistance and deformation of the damper were measured to study the viscoelastic damper properties dependence on frequency and amplitude. Mechanical properties including shear storage modulus, shear loss modulus, loss factor and energy dissipation are studied. Experimental results show that the small size damper’s mechanical properties are significantly related to its loading frequency and amplitude. The energy dissipation capacity of the damper was stable under different loading frequency and amplitude.

An analytic solution for form finding of GFRP elastic gridshells during lifting construction

The GFRP elastic gridshell is a type of spatial structure composed of long continuous hollow GFRP members and has been used in large-span roof structures. The elastic gridshell achieves its shape as the result of elastic deformations during the construction process of lifting or pushing. The shape-forming mechanism of such structures is very complicated due to significant geometric non-linearity. This research aims to propose analytic formulations to estimate the structural features of the GFRP elastic gridshell under lifting construction. An analytical theory, considering the large geometric deformations, is first presented for analyzing single lifted member. Based on the given theory and an iteration process, a form-finding method is further proposed for predicting the deformation, nodal forces and bending moment of biaxial symmetrical GFRP elastic gridshells during the lifting construction. The form-finding method is realized on the Matlab platform and a case study is carried out. Finite element analysis is further conducted to validate the accuracy and practicability of the proposed method. Results show that, the analytic theory is highly accurate for the analysis of lifted members, and the proposed form-finding method is applicable in predicting the structural behaviors of GFRP elastic gridshells for which the lifting construction is adopted.

Effect of Gravity on the Scale of Compliant Shells

Thin shells are found across scales ranging from biological blood cells to engineered large-span roof structures. The engineering design of thin shells used as mechanisms has occasionally been inspired by biomimetic concept generators. The research goal of this paper is to establish the physical limits of scalability of shells. Sixty-four instances of shells across length scales have been organized into five categories: engineering stiff and compliant, plant compliant, avian egg stiff, and micro-scale compliant shells. Based on their thickness and characteristic dimensions, the mechanical behavior of these 64 shells can be characterized as 3D solids, thick or thin shells, or membranes. Two non-dimensional indicators, the Föppl–von Kármán number and a novel indicator, namely the gravity impact number, are adopted to establish the scalability limits of these five categories. The results show that these shells exhibit similar mechanical behavior across scales. As a result, micro-scale shell geometries found in biology, can be upscaled to engineered shell geometries. However, as the characteristic shell dimension increases, gravity (and its associated loading) becomes a hindrance to the adoption of thin shells as compliant mechanisms at the larger scales-the physical limit of compliance in the scaling of thin shells is found to be around 0.1 m.

Analysis of load bearing structure of selected hall buildings

In this paper the issues associated with correct design of hall buildings has been presented. Large span roof structures require a particularly careful approach to design issues. In this paper examples of two building hall were presented. In the first example, the construction disaster occurred, while in the second of presented buildings due to the changes introduced while construction has been protected against such disaster. The first of the analyzed cause concerns storage hall, whose roof structure has been destroyed due to heavy rainfall. The main cause of this disaster was the malfunction of vacuum roof drainage system compounded by a number of design errors. Mentioned errors were not eliminated, during construction, despite the additional investor supervision, which was independent of parties involved in a construction process. The second case concerns the structure of a sports hall, which was built next to the existing school. Under construction of the hall building, the contractor and the supervision inspector, in conjunction with the designer, introduced a number of modifications of the structure to prevent the disaster. These modifications were a direct result of errors at the design stage, which were eliminated under the construction works. Based on analyzed cases, the scope of diagnostics, which should be performed during the operation of hall buildings with large roof areas, was determined.

Analyzing the background and resonant effects of wind-induced responses on large-span roofs

Estimating the wind-induced responses is a crucial task in the wind-resistant design for large-span roofs. Due to the complexity of the aerodynamic and structural dynamic properties, the background and resonant effects on large-span roof structures are difficult to be estimated and understood by civil engineers. This paper defines the basic response as the quasi-static response subjected to completely coherence wind load. On this basis, conceptual analyses on the background and resonant effects are carried out. Through 18336 samples of wind tunnel data on typical flat, cantilevered, cylindrical, spherical, and saddle large-span roofs, 23940 cases of parametric wind-induced response analyses are conducted. The parametric analysis results turned out to be supportive and complementary to the conceptual analysis results. Finally, the principles and empirical formula of the background and resonant factors are summarized, which leads to better understanding of the wind-induced effects on large-span roof structures for engineers. The approach can also be used for quick estimating the equivalent static wind loads in engineering practices, especially in the preliminary design stages.

Coupled Finite Volume and Finite Element Method Analysis of a Complex Large-Span Roof Structure

The main goal of this paper is to present coupled Computational Fluid Dynamics and structural analysis for the precise determination of wind impact on internal forces and deformations of structural elements of a longspan roof structure. The Finite Volume Method (FVM) serves for a solution of the fluid flow problem to model the air flow around the structure, whose results are applied in turn as the boundary tractions in the Finite Element Method problem structural solution for the linear elastostatics with small deformations. The first part is carried out with the use of ANSYS 15.0 computer system, whereas the FEM system Robot supports stress analysis in particular roof members. A comparison of the wind pressure distribution throughout the roof surface shows some differences with respect to that available in the engineering designing codes like Eurocode, which deserves separate further numerical studies. Coupling of these two separate numerical techniques appears to be promising in view of future computational models of stochastic nature in large scale structural systems due to the stochastic perturbation method.

Advantages of Filter Approaches for the Determination of Wind-Induced Response of Large-Span Roof Structures

AbstractThe wind-resistant design process of roof structures is a complex task due, inter alia, to the temporal-spatial distribution of fluctuating wind loading and to multimode vibration. This pro...

Comparison of the Performance of Hexagonal Grid and Half-cuboctahedron Grid Tensegrity Systems in Roof Structures

Objective: To study and compare the behaviour of half-cuboctahedron grid and hexagonal grid tensegrity system. Methods/ Statistical Analysis: Ever since the discovery of tensegrity, most works have been concentrated on the classification and form finding techniques but very less on the mechanics of these structures. This study focus on the behaviour of two basic tensegrity modules, the half-cuboctahedron and hexagonal. Findings: Later, the study has been extended to tensegrity grids of spans 2x2, 4x4 and 8x8 of both the configurations (hexagonal modules and half-cuboctahedron modules) which were developed using an FEM based software. The grids were compared on the basis of nodal displacements and member forces, resulting in the half-cuboctahedron grid to be a more feasible configuration for large span roof structures. Applications/ Improvements: The application of the tensegrity structure is to applied in the large span roof structures.