Search

Abstract Single-layer reticulated domes are very common spatial structures. As landmarks, these types of structures can more easily be the targets of terrorist attacks than other buildings. However, blast resistance is not taken into consideration in the design of most civil structures. Therefore, it is important to know the damage level that may be imparted to single-layer reticulated domes after a blast attack. In this study, the dynamic response of reticulated domes subjected to an interior blast was investigated with numerical simulations, and five typical failure modes were identified from the results. In addition, the effects of some important parameters were investigated with a case study. Relationships between failure modes and interior blast impulses were summarised. Finally, the failure mechanisms were analysed, which could provide some design suggestions to decrease the probability of severe damage in spatial structures subjected to extreme dynamic loads. Highlights • Five failure modes of single-layer dome subjected to interior blast were identified. • Effects of common parameters were numerical investigated and compared. • Relationships between failure modes and interior blast impulses were summarised. • Failure mechanisms of the dome under interior blast loading were interpreted. • Suggestions for decreasing the probability of severe structural damage were given. [ABSTRACT FROM AUTHOR]

A commercial finite element package, LS-DYNA, was employed to simulate the response of a single-layer reticulated dome to an interior blast. The dome, which was initially stressed by static preloading, encountered an interesting phenomenon namely counter-intuitive collapse, which was found during the blast analysis. The Johnson–Cook constitutive model for mild steel was used to identify different failure modes of the dome for more than 2430 samples. A seemingly counter-intuitive collapse was identified due to dynamic instability. This unusual collapse was explained using total potential curves, and the critical blast load was defined. The effect of different static preloads, which is the other determination factor of counter-intuitive collapse, was investigated. A relationship between collapse and static/dynamic loads was also obtained. The results indicate that single-layer reticulated domes, with large initial stresses, may collapse at lower dynamic loads than expected. [ABSTRACT FROM AUTHOR]

Abstract: Initial curvature of members is an inevitable geometrical imperfection for reticulated domes. To investigate the stability of single-layer domes with initial curvature of members, the multi-beam method was presented to simulate the initial curvature of members, and two modeling methods were adopted to introduce the initial curvature of members for reticulated domes by means of ANSYS. First, the random imperfection mode method was introduced according to the randomness of initial curvature of members. The example of a Kiewitt-8 dome was used to explain the method and investigate the influence of angle and amplitude random variables on the stability of reticulated domes. Second, the modified consistent imperfection mode method was obtained, which was an efficient method to evaluate the lowest buckling load of the structure with initial curvature of members. Based on this method, the Kiewitt-6 and Kiewitt-8 single-layer reticulated domes were taken as examples to analyze the stability of structures with initial curvature of members, and the influences of initial curvature of members on the ideal structure and the structure with nodes deviation were obtained quantitatively. The results show that, for the ideal structure and the structure with nodes deviation, initial curvature of members can decrease the buckling load of the structure obviously. Initial curvature of members can change the buckling mode and plasticity development of the structure. The influence of initial curvature of members on the elasto-plastic stability of single-layer reticulated domes cannot be neglected. [Copyright &y& Elsevier]

Abstract: Investigation of elasto-plastic stability of reticulated shells has gradually become more and more attractive to researchers. However, the analysis of the elasto-plastic stability is much more complicated than the elastic analysis, because of the involvement of both the geometrical nonlinearity and the material nonlinearity and the interactions of the two. Taking into consideration of material nonlinearity, the elasto-plastic stability behaviour of reticulated shells will be significantly different, which can only be revealed by large amount of geometrically and material nonlinear analysis of the structures. The elasto-plastic stability of seven types of commonly used single-layer reticulated shells (Kiewitt-8, Kiewitt-6, Geodesic, Schwedler Bidirectional, Schwedler Monoclonal, Sunflower, and Radial Rib) was investigated systematically with ANSYS, in which more than 2000 cases of geometrically and material nonlinear analysis were conducted with different initial geometrical imperfections, geometrical, structural and load parameters. Based on the analytical results and via comparison between elastic and elasto-plastic buckling loads, the plasticity influence coefficients were summarized for each type of the reticulated domes. These coefficients can be used to predict accurately the elasto-plastic buckling load in design practice of the reticulated domes, which is an easy way for designers to evaluate stability of the reticulated shells. [Copyright &y& Elsevier]

Abstract: This paper addresses the issue on dynamic collapse mechanism of single-layer reticulated shells subjected to harmonic load, sudden load and seismic load. The method for failure mechanism has reviewed the relationship between the response of the reticulated shell and the peak acceleration of dynamic action. Besides, the steel damage accumulation is considered in the method by compiling a user subroutine based on the computing program ABAQUS. An example is introduced to describe dynamic instability collapse resulting from geometric nonlinearity of the shell and the other example is presented to describe strength failure resulting from excessive development of plastic deformation, for it is discovered that the structure is not only to be prone to instability collapse in dynamic action. According to the responses of the single-layer reticulated shell under dynamic loads, this study discusses the relationship between the failure model and the corresponding dynamic load parameters. Then, the method for distinguishing failure modes is proposed based on the fuzzy synthetic evaluation theory and the structural responses of sufficient samples at the failure state. The technique feasible to be used to distinguish different failure modes of single-layer reticulated shells under different dynamic loads is validated. [Copyright &y& Elsevier]

This paper presents experimental studies on the plastic behavior of circular steel tubes subjected to transverse low-velocity mass impact. A total of 73 impact tests and 7 quasi-static tests were conducted on the circular steel tubes, which have span lengths of 900, 1200 and 1500 mm. Three representative indenters, i.e., wedge-shaped, hemispherical and cylindrical indenters, were used to impact the specimens, which were fully clamped at both ends by a specially designed clamping system. The impact energy was sufficient to ensure the structural collapse of the tube due to tensile tearing. Both the impact and quasi-static test results showed that the fully clamped steel tube under transverse impact loads involved the three-hinge mechanism to deform. Based on experimental observations, four deflection modes and four failure modes were proposed. Moreover, the plastic dent zones were described in detail. The influences of the geometrical parameters, indenter types and local denting on the magnitudes of the dent zone length and the transverse load were investigated and discussed. Based on the test results, empirical formulae for calculating the length of the plastic dent zone and the transverse load were proposed. These formulae are useful for engineers to evaluate these two values in practice. Good agreement was achieved between the experimental and the predicted results. [ABSTRACT FROM AUTHOR]

The aim of this paper is to evaluate the bending stiffness of a new bolted-plate joint for single-layer or double-layer reticulated shells. In order to investigate the performance of the joint, experimental tests and numerical simulations were undertaken. ANSYS was used for the numerical study, with contact elements (target 170 and contact 174) and solid elements (solid 187), used to establish bending stiffness curves for the bolted-plate joints. The good agreement between numerical simulation and experiment indicated that the simulation is an accurate and effective way of evaluating the mechanical properties of the bolted-plate joint system. In addition, using nonlinear beam elements (beam 189 element) with end spring elements (combin39), the single-layer reticulated cylindrical shell with bolted-plate joints was analyzed for different rise to width ratios. The analyses determined the load-bearing capacity of the shell. It is concluded that the bolted-plate joint system is a good choice for space structures with small or medium spans. [ABSTRACT FROM AUTHOR]

Abstract A general forming method for super-long span mega-latticed structures has been developed, based on the key parameters for five types of structure, together with a finite element model. The method combines the molding idea for universal spherical mega-latticed structures and the geometric topological relations of the improved traditional single-layer reticulated shell. The static and economic indexes of six kinds of 800 m span mega-latticed structures, with the same geometry, control parameters and loads, were calculated, and the force law for these structures under static load identified. Then structures suitable for spans of 1000 m and 1200 m were considered. The static performance and economic indexes showed that the mechanical and economic performance of the Geodesic type mega-latticed structure and the Three-dimensional grid type mega-latticed structure were excellent. In order to promote the engineering application of these structures, the influence of four key parameters on the performance of 1000 m structures was studied, and a reasonable range of indicative parameters obtained. Highlights • It is proved that the modeling method is universal for spherical mega-latticed structures. • The paper can better explain the static properties and the stability of super-long mega-latticed structures. • It is proved that the structure types selected have good mechanical properties and economic performance. • It is proved that through the method of parameter analysis, economic and reasonable structures can be obtained. [ABSTRACT FROM AUTHOR]

The temperature effect often significantly affects the performance of large-span spatial structure and even becomes one of the controlling loads. To obtain the non-uniform temperature field distribution of the thin-walled steel members under solar radiation and the influence rules of various factors, in this paper, experimental studies are carried out with three groups of specimens including rectangular steel tube, I-shaped steel and circular steel tube. Based on the test data, the non-uniform temperature field distributions considering the influence of solar radiation intensity, member size and surface coating are analyzed in detail. Then, numerical methods for the temperature field of steel members are studied considering multiple environmental factors. The validity of the numerical method is evaluated with test results. Finally, based on the parametrical studies of the major influence factors, a simplified calculation approach is presented for practical engineering applications. The experimental study demonstrates that the non-uniform temperature distribution of steel members truly exists and cannot be overlooked. The numerical method for the temperature field in this paper is effective, and the simplified calculation approach can meet the required engineering precision. The research methods and conclusions of this work can provide valuable references for thermal design, monitoring and control of steel structures. [ABSTRACT FROM AUTHOR]

A comparison was made of the static behavior of a double-layer reticulated shell, a local triple-layered reticulated shell, a ribbed type mega-latticed structure and a Kiewitt type mega-latticed structure with the same geometrical parameters and loads. The results show that the Kiewitt type mega-latticed structure has the best structural performance. Then a complex structural configuration was analyzed in detail, using CAD 3D modeling, and a command-flow was developed to create the new structure automatically by ANSYS Parameter Design Language as an innovative structural-programming method. The static analysis and comprehensive stability analysis were conducted. The reasonable values of parameters for the overall buckling mode were summarized and the ultimate bearing capacity was accurately obtained by considering geometrical nonlinear, material nonlinear and initial curvature of the members. The nonlinear equilibrium paths were traced using the Arc-length method. Results indicate that the 800 m Kiewitt type mega-latticed structure has a very low sensitivity to geometrical nonlinear and a low sensitivity to initial curvature of members, but a high sensitivity to material nonlinear. Therefore, the Kiewitt type mega-latticed structure could be regarded as a reasonable super-large span structure with several advantages, including reasonable stresses, clear force transmission lines, economic steel consumption, high stiffness and good bearing capacity. [ABSTRACT FROM AUTHOR]

Single-layer reticulated domes are typical structures with high degree of static indeterminacy. The stability of the reticulated dome structures is complicated and closely related to both the member buckling and the overall buckling of the structure. However, little theoretical research work deals with this very complex phenomenon. Meanwhile, for the statically indeterminate structures, it is a common belief that the local failure would occur first and result in the change of internal force paths, while the structure could support load continually before the overall collapse of the structure. In this paper, the interaction between the member buckling and the overall buckling of the structure was investigated, and this common belief was explored. The geometrically and materially nonlinear analyses (GMNA) were carried out for the reticulated domes with eight types of different grid forms, and the examination of member buckling for each dome was conducted based on the examination method of the P – δ end curve or the P – δ mid curve of the member. The relationship between the member buckling and the global instability of the structure was obtained by evaluation results of member buckling. Consequently, for the common reticulated domes, two instability patterns were identified, i.e. progressive instability and synchronous instability. In the case of progressive instability, the member buckling occurs in advance of the overall buckling of the structure. Then the number of the instable member increases, and finally the overall buckling of the structure occurs. In the case of synchronous instability, the member buckling and the overall buckling of the structure happen simultaneously. The interaction mechanism between the member buckling and the global instability of the structure was analyzed for both instability patterns. [ABSTRACT FROM AUTHOR]