• International Journal of High-Rise Buildings
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• v.8 no.2
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• pp.83-94
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• 2019

Diagrid structures have emerged in recent decades as an innovative solution for tube tall buildings, capable of merging structural efficiency and aesthetic quality. This paper investigates the effect of the building slenderness (grossly quantified by means of the aspect ratio, i.e., the ratio between the height and the plan dimension) on the structural behavior and on the optimal design parameters of diagrid tall buildings. For this purpose, building models with different slenderness values are designed by adopting preliminary design criteria, based on strength or stiffness demands; in addition, a design method based on a sizing optimization process that employs genetic algorithms is also proposed, with the aim to compare and/or refine the results obtained with simplified approaches.

• International Journal of High-Rise Buildings
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• v.12 no.2
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• pp.153-162
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• 2023

Achieving sustainable spaces is one of the emerging trends of tall buildings regarding their significant impacts on the cities. Reducing energy consumption and material using is investigated as a widely used approach to achieve more efficient tall buildings. Defining more efficient geometries and form modifications have been adopted for this goal. In this paper the effect of plan shape and diagrid angle on structural efficiency of diagrid tall buildings have been studied. A parametric workbench is applied to generate and analyze models. The goal is to find effective form parameters resulting in more efficient forms. Respectively, all models were generated in Rhino/grasshopper architecturally and analyzed by a finite element plug-in structurally. Based on the results, steeper angles almost cause more displacements and needs to be more stiffened. it can be seen almost more sided models need less weight for the structures and it could lead to more efficient forms.

• Nuclear Engineering and Technology
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• v.16 no.2
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• pp.70-79
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• 1984

With the help of the nuclear computational system for a large LMFBR (KAERI-26 group cross section library/1DX/2DB), the reactivity coefficients for the diagrid expansion and the pad expansion at the beginning of cycle of the equilibrium core of SUPER-PHENIX I are calculated and reviewed. the core is described using R-Z geometry model, and a two-dimensional multigroup diffusion theory is used. For reference cases, reactivity calculations for radial and axial uniform expansion are performed, and also calculated are reactivity variations due to changes in material density and core volume. The reactivity coefficient for the diagrid expansion is calculated to be -0.553pcm/mil. The temperature coefficient corresponding to the above value is -1.0766pcm/$^{\circ}C$ and is well in accord with the French datum of -1.09pcm/$^{\circ}C$ within 1.2% difference. With the use of 4he calculational method for the diagrid expansion effect, reactivity calculations for the pad expansion bringing about nonuniform expansion are performed, which show that the calculational method is very useful in the analysis of the pad expansion effect. The reactivity coefficients for the pad expansion are calculated to be -0.2743 pcm/mil and -0.2786pcm1mi1 for the averaged expansion model and for the integrated pancake model, respectively. Under the assumption of the free expanding core the temperature reactivity coefficients for each model are obtained to be -0.5766pcm/$^{\circ}C$ and -0.5858pcm/$^{\circ}C$, both of which agree with the French datum of -0.574pcm/$^{\circ}C$ within 2% difference.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.24 no.3
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• pp.307-317
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• 2011

This paper is to investigate the possibility of the elastic seismic design for highrise buildings through seismic performance evaluation for potential earthquakes that wind-designed highrise buildings located in strong wind zone and low seismicity can be experienced. Highrise steel diagrid frames which is the most loved structural system in recent years were wind-designed and the substantial system overstrength due to wind design procedure is verified, For the highrise steel diagrid frames, the response spectrum analysis and the seismic performance evaluation by various soil sites were conducted. It was showed that highrise steel diagrid frames with slenderness of greater than 5.2 under strong wind and low seismic zones such as Korea peninsula can resist elastically for the 500 year return period earthquake and have the possibility of seismic design for the 2400 year return period earthquake. In the member level, highrise steel diagrid frames with slenderness of greater than 5.2 all presented the immediate occupancy level regardless of soil sites for the 500 year return earthquake and excluding the $S_E$ soil site for the even 2400 year return period earthquake. In the system level, highrise steel diagrid frames with slenderness of greater than 5.2 showed the immediate occupancy level for $S_A$ and $S_B$ soil sites and the life safety for $S_C$ to $S_E$ soil site in the 500 year return period. The seismic performance level of highrise steel diagrid frames for the 2400 year return period earthquake displayed one step lower than the 500 year return period earthquake.

• Journal of Korean Society of Steel Construction
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• v.22 no.3
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• pp.229-239
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• 2010

As a new structural system, the diagrid system resists both gravity and lateral loads with diagonal columns. In current seismic design provisions, however, the response modification factor for a new structural system is not provided yet. ATC-63 provides a new methodology for defining various seismic performance factors, including the response modification factor. ATC-63 includes the collapse margin ratio in modifying the response modification factor, which can vary with many structural systems. In this paper, a non-linear static analysis and a dynamic analysis were conducted for four different diagrid models with 4-to 36-story heights. From these analyses, the response modification factor of the diagrid system was evaluated.

• Journal of The Korean Digital Architecture Interior Association
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• v.12 no.1
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• pp.5-13
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• 2012

The frame of pipe greenhouses in Korea have been collapsed increasingly due to very weak in structure caused by the heavy snow and strong wind. In order to reduce the collapse of green houses, it is urgent to develop the new structural system in stress tolerant greenhouses. Therefore, this paper performed the structural analysis of greenhouse frame in accordance with snow loads and wind loads. Three type models in structural frame configuration of greenhouses, that is, existing type, diagrid type, and honeycomb type are selected. It was classfied the section shape of structural frames in greenhouses into arch style, standard style, and diagonal standard style. As a result of this paper, it was verified that the structural system of diagrid type is better than that of existing type against snow loads and wind loads in the frame of greenhouses.

• International Journal of High-Rise Buildings
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• v.5 no.4
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• pp.293-304
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• 2016

The diagrid structural system for constructing tall buildings is a recent invention. Debuting in 2004 with the construction of the Swiss Re Tower in London, this aesthetically driven structural system has centered the perfecting of its technology on the development of the nodes that form its innovative deviation from standard steel tall framing methods. The paper examines variations in node design, understanding the linked dependence the modularity and the choice to expose the steel in the building, as well as on advances in digital modelling that allow an increasingly seamless line of communication from the engineering design through to the actual fabrication of the nodes. This advanced design and fabrication technology will be seen to have resulted in the expanded use of the technical term "node" to inform the design and construction of a range of other applications in the structuring of tall buildings, including the use of steel castings.

• International Journal of High-Rise Buildings
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• v.5 no.4
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• pp.305-318
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• 2016

In the design of super-tall towers, engineers often find the conventional frame systems used in countless buildings in the past decades incapable of providing the required form, performance and constructability demanded by super-tall heights. The strength of the diagrid as a structural system in high-rise towers is the total flexibility it affords the designer as an adaptable, efficient and buildable scheme. Using fundamental engineering principles combined with modern computational tools, designers can take minimum load path forms to create rationalized diagrid geometries to create optimized, highly efficient towers. The use of diagrid frames at SOM has evolved as a structural typology beginning with the large braced frames on the John Hancock Center and continued in modern applications proving to be a powerful system in meeting the demands of supertall buildings.

• Steel and Composite Structures
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• v.16 no.3
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• pp.289-303
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• 2014

In recent, development of construction and design technology gives taller, larger and heavier steel framed structures. With the tendency of increasing high-rise building, this study is strongly related to structural system, one of significant components in structural design. This study presents an innovative structural system, with high performance steel material, diagrid. Its detail, structural analysis, and structural experiments are all included for the development of new structures.

• Journal of Korean Association for Spatial Structures
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• v.10 no.2
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• pp.105-115
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• 2010

Recently, High-rise building are irregular-shaped to be city landmarks and function as vertical cities to enable the efficient use of land. 3T (Twisted, Tilted & Tapered) designs are being suggested for irregular buildings and studies to develop new structural system have been actively made to satisfy slender shape ratio. In diagrid system, not only gravity load but also lateral load is delivered based on the triangular shape of diagrid, so most of columns are eliminated. Because shearing force is delivered by the axial behavior (tensile/compressive) of diagrid to minimize shearing deformation, the system is more applicable to irregular buildings than existing system where shearing force is delivered by the columns. In this study, the process of selecting connection details and the structural safety of the selected details are verified using the finite element analysis with focus given to the construction overview of the Cyclone Tower. However, the relersed methods of stress concentration are suggested and the performance of stress concentration relieves that it's suggested for the appropriate cap plate thickness and extended length.