Search

Summary: Twisted diagrid tube structures have become popular due to their significant lateral resistance and esthetic potential. However, the ductility and energy dissipation capacity of twisted diagrid structures are poor. This paper presents a seismic resilient fused structural system named the twisted diagrids with shear links (TDSL), and the performance‐based plastic design (PBPD) method is introduced for designing a 24‐story prototype structure. The numerical model of the TDSL prototype is established, then nonlinear static and dynamic analyses are conducted to evaluate the seismic behavior of the prototype. The results reveal that the TDSL system can significantly improve the post‐yield performance compared to the conventional twisted diagrid structure, and the performance objectives are achieved properly. Subsequently, incremental dynamic analyses are carried out to investigate the collapse fragility of the TDSL prototype, and the collapse risk of the prototype is assessed by FEMA P695. The results indicate that the TDSL prototype has satisfactory collapse‐resisting capacity under earthquakes. It is also found that corner columns can improve the seismic safety of the prototype against collapse. In general, the TDSL system is an appealing choice for twisted buildings in seismic regions. [ABSTRACT FROM AUTHOR]

Summary: Twisted forms have been widely employed in high‐rise buildings in recent years. The diagrid structural system is particularly suitable for twisted buildings because of its large lateral stiffness and unique architectural esthetics, but little research on twisted diagrid tube structures is currently available. This paper studies the influence of diagonal angle, twist rate, aspect ratio, corner column, and plan form on the lateral stiffness of twisted diagrids, and the optimal diagonal angle range is determined. Considering the stiffness and strength criteria, the design methodology of diagonal sizes of twisted diagrids is proposed, and the methodology is validated by finite element analysis. In addition, this paper presents a novel configuration of twisted diagrid, that is, the twisted diagrid with asymmetric diagonal angles. The influence of the left‐ and right‐inclined diagonal angle on the lateral stiffness of twisted diagrids is investigated. It is found that twisted diagrid structure with asymmetric diagonal angles exhibits larger lateral stiffness than the symmetric case. The results in this paper are useful for engineers to determine the configuration and diagonal sizes of the twisted diagrid tube structures. [ABSTRACT FROM AUTHOR]

Diagonal arrangement is a prerequisite for diagrid tube structures in preliminary design. Two scenarios made up of curved or varying-angle straight diagonals, all established by only two basic geometric variables, i.e. the bottom angle and the top angle of the control arc or straight diagonal, are evaluated under seismic and wind loads. Approaches to configuring diagrid tube structures of these two types are introduced graphically. A set of diagrid tube structures composed of curved and straight diagonals with various combinations of bottom and top angles, with height-to-width aspect ratios ranging from 3.6 to 9, are investigated focusing on the optimal geometries in terms of the material usage. By giving attention to both seismic and wind loads, the optimal values of bottom and top angles are suggested respectively for these two types of diagrid tube structures with different aspect ratios. Furthermore, the proposed method is validated by FEM analysis. Consequently, the structurally efficient use of diagrid tube structures with curved or varying-angle straight diagonals could be provided conveniently for both engineers and architects in preliminary design. Copyright © 2014 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

A new type of combined cable-stayed bridge, named the extradosed and intradosed cable-stayed bridge with continuous cables, is presented to improve the mechanical behavior of the traditional extradosed bridges. The cable-girder anchorage is innovated to be suited for traditional extradosed bridges, which makes the girder supported by a group of continuous cables with larger eccentricity above and under the deck simultaneously. This paper evaluates the structural performance of the innovative structural scheme through parametric studies and detailed comparisons with traditional ones. Preliminary analyses show the advantages of the innovative structure, such as decreased bending response and deflection of the deck because of larger stiffness, smaller cable forces and increments, better dynamic resistance, and less amount of material. [ABSTRACT FROM AUTHOR]

This paper presents preliminary design guidelines specifically for diagrid tube structures composed of straight diagonals with gradually changing angles. A graphic approach to configurating a diagrid of this type is introduced, with two basic geometric variables involved, i.e. the bottom and top diagonal angles. In terms of both stiffness and strength design criteria, a methodology for calculating diagonal member sizes is developed and applied to a set of diagrid tube structures with height-to-width aspect ratios ranging from 3.6 to 9. The diagrid tube structures are designed with various combinations of bottom and top angles in order to investigate the effects of bottom and top angles on the material usage. Based on the results, the optimal values of bottom and top angles are suggested, then, the optimal geometries for diagrid tube structures with different aspect ratios are determined. This paper attempts to help the designer arrange the structurally efficient diagrid layout conveniently and perform approximate calculations of the diagonal member sizes. Copyright © 2010 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Studies the plastic buckling patterns of axially compressed cylindrical shells made of ductile materials. Background information on the study; Elastoplastic shell material; Plastic bifurcation analysis under displacement control; Numerical method for bifurcation analysis for cylindrical shells; Effect of boundary conditions on nonaxisymmetric buckling mode; Summary and conclusions.

Investigates the cyclic-localization behavior of axisymmetric plastic buckling patterns of cylindrical shells in terms of influence on strength deterioration. Geometric and material nonlinear analysis of cylindrical shells; Nonlinear finite element analysis of axisymmetric cylindrical shells; Plastic bifurcation analysis under displacement control; Experimental verification; Conclusion.