Kyoung Sun Moon

Optimal Grid Geometry of Diagrid Structures for Tall Buildings

Abstract The use of diagrid structural systems for tall building design has continued to increase. Characteristics and stiffness-based preliminary design methodology of diagrid structures are discussed. The design methodology is applied to a set of diagrid structures, 40, 50, 60, 70, and 80 stories tall. The diagrid structure of each storey height is designed with diagonals placed at various uniform angles as well as gradually changing angles along the building height in order to determine the optimal uniform angle for each structure with a different height and to investigate the structural potential of diagrids with changing angles. Based on these design studies, design guidelines are provided for the optimal configuration of the diagrid structure grid geometry within a certain height range.

Sustainable Design of Diagrid Structural Systems for Tall Buildings

The diagrid structural system has widely been used for tall buildings due to its structural efficiency and distinctive architectural aesthetic potentials. This paper extends the previous studies on diagrids by further investigating more efficient diagrid configurations which require less amount of structural material to meet design requirements. Today, sustainable design to save our limited resources is one of the most important building design issues, especially for tall buildings constructed with an abundant amount of resources. Diagrid structures of uniform and various varying angle configurations are studied to determine more efficient geometric configurations of the system.

Sustainable Structural Systems and Configurations for Tall Buildings

Tall buildings are built with an abundant amount of resources because of their enormous scale. This paper presents sustainable structural engineering strategies for tall buildings, which will lead to the construction of tall buildings with less amount of structural material to meet design requirements. Selecting a particular structural system for tall building design involves many complex factors such as availability of resources, architectural aesthetics, spatial organizations and structural efficiency. Among these various factors, this study mainly investigates lateral stiffness-based structural efficiency of today’s prevalent structural systems for tall buildings, such as diagrids, braced tubes and outrigger systems. Design optimization strategies for important structural geometric configurations are studied. Further, optimal stiffness distribution between the building core and perimeter structure is discussed. Through the most appropriate system selection and design optimization, more sustainable built environments can be accomplished.

Optimal Configuration of Structural Systems for Tall Buildings

Structural systems for tall buildings have evolved to produce higher lateral stiffness more efficiently, and the efficiency of a structural system is significantly influenced by its geometric configuration. Therefore, once a particular structural system is selected for a tall building, it should be configured very carefully to maximize its structural efficiency and, at the same time, satisfy other non-structural design requirements integratively. This paper investigates optimal configurations of today’s prevalent structural systems for tall buildings. Among various structural systems developed for tall buildings, the systems with diagonals are generally more efficient because they carry lateral loads by their primary structural members’ axial actions. When the primary lateral load resisting system is located over the building perimeter, the system’s efficiency can be maximized. Tall building structural systems with perimeter diagonals include braced tubes and more recently developed diagrids. Braced tubes of various column spacing and diagonal configurations are comparatively studied. Diagrid structures of various uniform and varying angle diagonals are studied to determine more efficient configurations. Another structural system widely used for today’s tall buildings is outriggers structures. Optimal stiffness distribution between the building core and perimeter mega-columns, connected to the core through outrigger trusses, is investigated for outrigger structures.

Comparative efficiency of structural systems for steel tall buildings

Structural systems for tall buildings have evolved to produce higher lateral stiffness more efficiently. This study investigates comparative structural efficiency between todays prevalent structural systems for tall buildings, based on lateral stiffness. Tall buildings of 40, 60, 80 and 100 storeys are optimally designed with braced tubes, diagrids and outrigger structures to meet the lateral stiffness requirements. The structural efficiency of each system is studied comparatively depending on building heights and height-to-width aspect ratios. More efficient system selection and design optimisation can substantially contribute to constructing sustainable built environments by saving building materials produced from our limited resources.

Braced Tube Structures for Complex-Shaped Tall Buildings

Braced tubes, which carry lateral loads by axial actions of the perimeter columns and bracings, are very efficient structural systems for tall buildings. This paper investigates structural efficiency of braced tube structures employed for complex-shaped tall buildings, such as twisted, tilted and tapered towers. For each complex form category, tall buildings are designed with braced tube systems, and their structural efficiency is studied in conjunction with building forms. In order to investigate the impacts of various important geometric configurations of complex-shaped tall buildings, parametric models are generated using appropriate computer programs, and the models are exported to structural engineering software for design and analyses. Based on the study results, structural efficiency of braced tubes for each complex form category is estimated.

Integrated Damping Systems for Tall Buildings

This paper investigates the potential of double skin facades (DSF), which are composed of two layers of facades with substantial gaps between them, as an integrated damping system for tall buildings. The connectors between the inner and outer skins of the DSF system are designed to have low axial stiffness with a damping mechanism. Through this design, the vibration of the primary building structure can be substantially reduced. However, the excessive movements of the DSF outer skin masses are a critical design limitation. In order to mitigate this limitation, the tuned mass damper (TMD)/DSF damping (DSFD) interaction system is studied. Compared to the conventional TMD system, the TMD/DSFD interaction system requires a significantly reduced TMD mass ratio. Compared to the DSFD system, the movements of the DSF outer skin masses can be substantially reduced in the TMD/DSFD interaction system.

Comparative Efficiency between Structural Systems for Tall Buildings of Various Forms

This paper investigates lateral stiffness-based comparative structural efficiency between today’s prevalent structural systems for tall buildings of various forms. Conventional rectangular box form tall buildings of 60, 80, and 100 stories are optimally designed first with braced tubes, diagrids, and outrigger structures to meet the identical lateral stiffness requirements. The structural efficiency of each system is studied comparatively depending on building heights and height-to-width aspect ratios. This study is expanded to investigate the comparative structural system efficiency of complexshaped tall buildings, such as twisted, tilted, and tapered towers. For each complex form category, tall buildings are designed again with diagrids, braced tubes, and outrigger systems. Comparative efficiency between these structural systems in conjunction with various complex building forms, heights, and height-to-width aspect ratios is studied. Parametric structural models are generated to investigate the impacts of various important geometric configurations of complex-shaped tall buildings. The parametric models are exported to structural engineering software for analyses, design, and comparative studies. More efficient system selection and design optimization can substantially contribute to constructing sustainable built environments by saving building materials produced from our limited resources.

Diagrid Structures for Complex-Shaped Tall Buildings

Diagrid structures are widely used for today’s tall buildings due to their distinguished architectural aesthetics in any existing urban context and structural efficiency in carrying lateral loads. With prevalent emergence of complex-shaped buildings throughout the world, this paper investigates structural efficiency of diagrid structures employed for complex-shaped tall buildings, such as twisted, tilted and freeform towers. For each complex form category, tall buildings are designed with diagrid systems, and their structural efficiency is studied in conjunction with building forms. In order to investigate the impacts of various important geometric configurations of complex-shaped tall buildings, parametric models are generated using appropriate computer programs, and the models are exported to structural engineering software for design and analyses. Based on the study results, structural efficiency of diagrids for tall buildings of each complex form category is estimated.

Sustainable Design of Braced Tube Structures: The Role of Geometric Configuration

Sustainability is one of the most important design issues today, especially for tall buildings, the construction of which requires an abundant amount of resources. Selecting and designing a particular structural system for a tall building does an important role in determining its sustainability in terms of structural material usage. The braced tube, developed in the late twentieth century for tall buildings, is a very efficient structural system because it carries lateral loads primarily by axial actions of the perimeter columns and bracings, and still prevalently used for contemporary tall buildings. This paper studies various geometric configurations of the braced tube to determine more efficient ones which use less amount of structural material to meet design requirements and consequently save our limited resources. Braced tubes of different perimeter column spacings, bracing shapes and bracing densities are studied comparatively. Based on the study results, more sustainable geometric configurations of the braced tube are presented.