Expose Diagrids Rev

DIAGRID STRUCTURES SYSTEMS CONNECTIONS DETAILS TERRI MEYER BOAKE

Diagrid Structures is available for pre-order on Amazon! Due for release January 20, 2014 WHAT IS A DIAGRID? The word “diagrid” is a blending of the words “diagonal” and “grid” and refers to a structural system that is single thickness in nature and gains its structural integrity through the use of triangulation. Diagrid systems can be planar, crystalline or take on multiple curvatures. Diagrid structures often use crystalline forms or curvature to increase their stiffness. This differentiates a diagrid from any of the three dimensional triangulated systems such as space frames, space trusses or geodesic structures, although it will be shown that some of the developments of diagrid structures have been derived from the details of these 3‐D systems. The diagrid structural systems that will be explored in this book will focus on the use of diagrid systems in the support of buildings, predominantly examining the perimeter systems that have come to be associated with mid‐rise to tall buildings. These perimeter diagrids normally carry the lateral and gravity loads of the building and are used to support the edge conditions of the floors. Diagrid type systems are also being used as roofs to create large column free clear spans. These types of (predominantly steel) systems have been derived from lamella structures. Where lamella structures may be made from a variety of materials, they predominantly use wood. The majority of lamella structures use a diamond grid and tend not to triangulate. The structural ideas behind the wood lamella contributed to the evolution of the steel lattice grid. Lattice grids are seeing increased use as a structural support system to enable the glazing of large courtyards and enclosed spaces. Lattice grids are designed to span relatively large distances without columns and they typically do not support floor loads. The steel detailing of the lattice grid system is significantly different from that of the perimeter structural diagrid for larger buildings. This type of structure was addressed in my previous book “Understanding Steel Design: An Architectural Design Manual” in the Chapter12: Steel and Glazing Systems. The design and technical exploration of diagrid structures addressed in this book will build on the introductory material addressed in “Understanding Steel Design: An Architectural Design Manual” in Chapter 9: Advanced Framing Systems: Diagrids. THE INTENTIONS OF THIS BOOK Although diagrids have their formative roots in engineering, this book is designed to explore a wide range of questions surrounding their contemporary use in service to architecture. This is not a book with calculations and it is not intended to replace the very necessary collaborative discussions that must take place amongst the architect, engineer and steel fabricator. The text will reference issues of scale and not the absolute size of members. Scale is a very important factor when looking at the relationship between the relative size and exposure of the steel structures to the spaces that they create and define. This would apply to the ultimate impact of diagrid structures on interior spaces as well as urban environments. Diagrid buildings tend to be purposefully selected to function as unique or iconic projects, and the diagrid has been employed to make the building stand out rather than blend into the surrounding urban fabric. FROM SHUKHOV TO FOSTER The origins of the diagrid structural typology lay at the crossroads of engineering and architecture. Engineering first as the initial explorations by Shukhov were intended to provide a structural system that served a civic works function that was not necessarily “architecture” in the purest sense of the word. The initial details and member choices were fairly utilitarian and simple. It is very important that Norman Foster has referenced the work of Shukhov as an inspiration for his diagrid explorations. This affirms the use of Shukhov’s towers as a precedent for buildings such as Swiss Re (30 St. Mary Axe) and the Hearst Magazine Tower. It also allows us to examine the changes that were made to the method of detailing and construction as the hyperbolic paraboloid form transitioned from a “hollow” tower to one that needed to support floor loads and was clad. This is a tremendous change in the role of the structure and the implications on the design, detailing and construction processes undertaken by Foster and ARUP in Swiss Re were significant. The decisions taken in the design of Swiss Re and the Hearst Magazine Tower continue to inform all variations of the diagrid to this date.

DIAGRID STRUCTURES: SYSTEMS, CONNECTIONS, DETAILS Terri Meyer Boake TABLE OF CONTENTS PREFACE 1. A COLLABORATIVE PROCESS  FROM SHUKHOV TO FOSTER  THE INTENTIONS OF THIS BOOK  THE IMPORTANCE OF COLLABORATION  THE ROLE OF BIM  WHY CHOOSE A DIAGRID?  DIAGRID DECISIONS, STEP BY STEP 2. EARLY EVOLUTION OF DIAGRID FRAMING SYSTEMS  BIRTH OF THE DIAGRID IN RUSSIAN CONSTRUCTIVISM  THE IMPACT OF THE MODERN MOVEMENT  GEODESIC DOMES AND SPACEFRAMES  THE EMERGENCE OF THE DIAGONALIZED CORE TYPOLOGY  THE APPEARANCE OF THE DIAGRID SUPPORTED OFFICE BUILDING  THE FORMATION OF THE CONTEMPORARY DIAGRID  A TIME OF STRUCTURAL CHOICE: Diagonalized Cores, Outriggers and Mega Columns 3. THE DEVELOPMENT OF THE CONTEMPORARY DIAGRID  THE CONCEPT AND DEFINITION OF A DIAGRID  EXPLORING THE POSSIBILITIES OF DIAGRID SYSTEMS  STRUCTURAL BENEFITS  THE FIRST CONTEMPORARY DIAGRID BUILDINGS o PROJECT PROFILE: LONDON CITY HALL | FOSTER+PARTNERS, ARUP o PROJECT PROFILE: SWISS RE | FOSTER+PARTNERS, ARUP o PROJECT PROFILE: HEARST TOWER | FOSTER+PARTNERS, WSP CANTOR SEINUK  TIMELINE SHOWING THE PROJECTS IN THIS BOOK 4. TECHNICAL REQUIREMENTS  DESIGNING FOR PERFORMANCE  WIND TESTING  SEISMIC DESIGN  FIRE PROTECTION SYSTEMS o Occupant Safety o Spray Applied Systems o Concrete Filled Tubes o Intumescent Coatings

5.         

6.       7.    

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8.       

MODULES AND MODULARITY ISSUES OF SCALE AND SHAPE GOVERNING STRUCTURAL PERFORMANCE CRITERIA MODULE SELECTION CRITERIA OPTIMIZING THE MODULE FOR STRUCTURAL PERFORMANCE OF TALL BUILDINGS BRACING OF THE DIAGONAL MEMBERS MODULES AND CORNER CONDITIONS IMPACT OF THE MODULE ON THE NODE IMPACT OF THE MODULE ON THE FAÇADE APPLICATIONS OF MODULES o Small Modules: 2 to 4 Storeys o Mid Size Modules: 6 to 8 Storeys o Large Modues: 10+ Storeys o Irregular Modules NODE AND MEMBER DESIGN WHAT IS A NODE? MATERIAL CHOICES THE BASIS FOR NODE DESIGN: SWISS RE AND HEARST THE IMPACT OF EXPOSURE ON DESIGN AND DETAILING o Concealed Systems o Architecturally Exposed Systems NODE ADAPTATIONS FOR CONCEALED SYSTEMS NODE ADAPTATIONS FOR ARCHITECTURALLY EXPOSED SYSTEMS CORE DESIGN MATERIAL TRENDS IN TALL BUILDING DESIGN THE IMPACT OF 9/11 ON CORE DESIGN THE PURPOSE OF A CORE IN A DIAGRID BUILDING STEEL FRAMED CORES o Centered Steel Cores o Offset Steel Cores o Steel Cores Outside of the Building o Steel Cores for Hybrid Diagrid Buildings REINFORCED CONCRETE CORES o Centered Concrete Cores o Concrete Cores for Narrow Plans o Concrete Cores for Highly Eccentric Loading o Concrete Cores for Supertall Buildings CONSTRUCTABILITY SAFETY ISSUES ARCHITECTURALLY EXPOSED VERSUS CONCEALED STEEL ECONOMY THROUGH PREFABRICATION AND REPETITION IMPACT OF NODE AND MODULE CHOICES ON ERECTION TRANSPORTATION ISSUES STAGING AREA AND SITE RELATED ISSUES MAINTAINING STABILITY DURING ERECTION

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FAÇADE DESIGN CLADDING AND FAÇADE TREATMENT TRIANGULAR GLAZING RECTILINEAR GLAZING INTERMEDIARY GLAZING SUPPORT, LATTICE GRIDS

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EXTERIOR DIAGRIDS WHEN AN EXTERIOR DIAGRID IS APPROPRIATE ISSUES WITH EXTERIOR STRUCTURAL DIAGRIDS DIAGRIDS AS DOUBLE FAÇADE SUPPORT SYSTEMS

10.

CONTEMPORARY PROJECTS  TALL BUILDINGS o THE LEADENHALL BUILDING, LONDON, ENGLAND ROGERS STIRK HARBOUR AND PARTNERS W/ ARUP o CAPITAL GATE, ABU DHABI, UAE RMJM ARCHITECTS o GUANGZHOU INTERNATIONAL FINANCE CENTER, GUANGZHOU, CHINA WILKINSON EYRE ARCHITECTS W/ ARUP o ARCELORMITTAL ORBIT TOWER, LONDON, ENGLAND ANISH KAPOOR, CECIL BALMOND W/ ARUP o DOHA TOWER, DOHA, QATAR ATELIERS JEAN NOUVEL  UNCONSTRUCTED VISONARY PROJECTS o LOTTE SUPER TOWER, SEOUL, KOREA SOM o CITIC TOWER, BEIJING, CHINA TFP ARCHITECTS

DIAGRID TIMELINE A timeline to look at the series of projects that will be addressed in this book in the context of the development of the diagrid, from the early work of Vladimir Shukov, through the diagonalized core typology, to the present. This is by no means a complete list of all of the diagrid buildings constructed to date. The sampling is global and intended to provide a thorough overview of the development of the system. Building Name Completion Building Height Diagrid Type Team Date m/ft No. of Floors Thumbnail Shukov Towers Designer: Vladimir Shukhov (various) Russia

IBM Building (United Ironworkers) ‐ Pittsburgh, PA, USA

1963

13 floors

concealed diagrid

John Hancock ‐ Chicago, IL, USA

1969

344m/1,128ft/ 100 floors

diagonalized Architect: SOM core Engineer: SOM

Bank of China ‐ Hong Kong

1990

367m/1,205ft/ 72 floors

diagonalized Architect: I.M. Pei core Engineer: Leslie E. Robertson Associates RLLP

London City Hall ‐ London, England

2003

10 floors

diagrid to support glazing

Architect: Foster + Partners Engineer: ARUP

Swiss Re (St. Mary Axe) ‐ London, England

2004

180m/590ft/ 40 floors

concealed diagrid

Architect: Foster + Partners Structural engineering: Arup Wind surveyor: Rowan Williams Davies & Irwin Inc. Facade consultant: Emmer Pfenninger Partner AG Contractor: Skanska UK Steel supplier: Hollandia BV and Victor Buyck Steel Construction NV Facade supplier: Schmidlin (UK) Ltd.

Architect: Curtis and Davis Architects Engineer: Leslie E. Robertson Associates RLLP

Hearst Building ‐ New York, NY, USA

2006


concealed diagrid

Architect: Foster + Partners Engineer: WSP Cantor Seinuk

Seattle Central Library ‐ Seattle, WA, USA

2005

11 floors

diagrid to support glazing

Architect: Rem Koolhaas (OMA) Engineer: ARUP

ROM ‐ Toronto, ON, Canada

2006

6 floors

concealed diagrid

Architect: Libeskind w/ Bregman and Hamman Engineer: ARUP

Canton Tower ‐ Guangzhou, China

2008

600m/1,969ft/

sightseeing tower, external AESS diagrid

Architect: Mark Hemel/Barbara Kuit/IBA Engineer: ARUP

SIPG Tower ‐ Shanghai, China

2008

37 floors

diagrid for double facade

Architect: East China Architectural Design and Research Institute

Tornado Tower – Doha, Qatar

2008


diagrid

Architect: CICO Consulting Architects and Engineers, SAIT Engineers: Stroh and Ernst AG

Guangzhou IFC ‐ Guangzhou, China

2010

439m/1,439ft/ 103 floors

AESS diagrid

Architect: Wilkinson Eyre Architects Engineer: ARUP

O‐14 ‐ Dubai, UAE

2010


concrete diagrid variation

Architects: Reiser + Umemoto Engineer: WSP Cantor Seinuk

Aldar HQ ‐ Abu Dhabi, UAE

2011


concealed diagrid

Architect: MZ Associates Engineer: ARUP

Capital Gate ‐ Abu Dhabi, UAE

2011


AESS diagrid

Architect: RMJM Architects Engineer: RMJM

KK‐100 ‐ Shenzhen, China

2011

442m/1,499ft/ 100 floors

diagonalized Architect: TFP core Engineer: ARUP

Al Bahar ‐ Abu Dhabi, UAE

2012


honeycomb

Architect: Aedas Engineer: ARUP

Doha Tower, Qatar

2012


AESS diagrid

Architect: Ateliers Jean Nouvel Engineer: Terrell Group, China Construction Design International

ArcelorMittal Orbit Tower ‐ London, England

2012

diamond diagrid

Architect: Anish Kapoor, Cecil Balmond Engineer: ARUP

Bow Encana ‐ 2012 Calgary, AB, Canada


AESS diagrid

Architect: Foster + Partners w/ Zeidler Engineer: Yolles

CCTV ‐ Beijing, China


concealed diagrid

Architect: Rem Koolhaas (OMA) Engineer: ARUP

2012

One Shelley Street ‐ Sydney, Australia

2012

Canadian Museum for Human Rights ‐ Winnipeg, MN, Canada

11 floors

concealed diagrid

Architect: Fitzpatrick and Partners Engineer: ARUP

2013

concealed diagrid

Architect: Antoine Predock Engineer: Yolles

Cleveland Clinic ‐ Abu Dhabi, UAE

2013

diagrid for double facade

Architect: HDR Architecture

Manukau Institute of Technology ‐ Auckland, New Zealand

2013

5 floors

AESS diagrid

Architect: Jasmax Architects (Stephen Middleton)

Leadenhall Building 2014 ‐ London, England


AESS diagrid

Architect: Rogers Stirk Harbour and Partners Engineer: ARUP

Lotte Super Tower ‐ 2015 Seoul, Korea

555m/1,819ft/ 123 floors

Vision – not built

Architect: SOM Engineer: SOM

Zhongguo Zun ‐ Beijing, China

528m/1,732ft/ 108 floors

Vision – not built

Architect: TFP Engineer: ARUP

2016

Hearst Tower (2004) Foster + Partners

Preface

STRUCTURE OF THE BOOK The general structure of the book is divided into two parts. The first part of the book is intended to be more instructional and will follow a logical order in terms of its approach to the sequence of topics and type of textual explanations. Images of the full range of projects that I have documented will be included as they are appropriate to the discussion at hand. The second section of the book will be divided into different classifications of diagrid applications: - Tall and Supertall versus mid-rise applications - Curved geometries - Crystalline geometries - Eccentric loading vs. normalized loading - Hybrid diagrid buildings This section will work towards creating a series of more detailed project profiles of each of the subject buildings, including the following documentation: - Detailed close-up shots of exterior and interior - Photo or drawing of the nodes - Structural axonometric of the building (preferably a Tekla/BIM model) - Construction images (if available) - Descriptions of the way the diagrid system has been incorporated into the design.

Bank of China, Hong Kong (1990) I.M. Pei Architect

1. Introduction

INTRODUCTION Diagrids or diagonal grids are a structural design strategy for constructing large buildings with steel. They create triangular structures with diagonal support beams. Diagrids require less structural steel than a conventional steel frame: Hearst Tower in New York City, designed by Sir Norman Foster, reportedly used 21% less steel than a standard design. The Diagrid also obviates the need for large corner columns and provides a better distribution of load in the case of a compromised building. Diagonalized grid structures have emerged as one of the most innovative and adaptable approaches to structuring buildings in this millennium. The use of diagrids as a formal structural language in buildings started in the early 2000s, examples being Swiss Re, London GLA and Hearst Tower, all from the offices of Foster + Partners with ARUP. Today, variations of the diagrid system have evolved to the point of making its use non exclusive to the tall building. Diagrid construction is also to be found in a range of innovative mid-rise steel projects. As a structural type their use is becoming more widespread, although information about how to best detail and take advantage of the system is lacking or generalized. The selection a diagrid system is often based on architectural choice rather than structural directive,however there are several functional and economic advantages that underlie the system: - increased stability due to triangulation - diagrids combine the gravity and lateral load bearing systems, thereby providing more efficiency - provision of alternate load paths in the event of a structural failure - reduced use of structural materials which translates into “carbon” or environmental savings - reduced weight of the superstructure translates into reduced load on the foundations - ability to provide structural support for a myriad of shapes (this has been a reason for the choice of cast concrete for many years as steel tended to be very orthographic) From the perspective of the project, there are aspects that can be very positive: - the need for a team approach given the complexity of the design and visual impact of the structure on the building design - a high level of cooperation between the architect and engineer - a higher freedom of expression possible given the innate stability of the frame - requirements of expertise and specialization from both architects and engineers

Guangzhou IFC - tallest diagrid building in the world

Capital Gate, UAE - most leaning diagrid in the world

Aldar HQ, UAE - only disk like diagrid building in the world

Swiss Re (2003) Foster + Partners

2. Development of the Diagrid

DEVELOPMENT OF THE DIAGRID This chapter will examine the history of the evolution of diagrid buildings as they evolved through several generations of bracing methods used for tall buildings. The section will include structural issues pertaining to the way that gravity and lateral loads are handled by the different bracing system methods. How is a diagrid different from a diagonally braced structure? Short history of changes in methods of diagonal bracing leading up to the invention of the diagrid. What is a diagrid? Discussion of diagrid terminology (node, module). Why choose a diagrid? (structural efficiency, redundancy) When not to choose a diagrid? (seismic limitations of certain systems, aesthetics, exposure, cost)

John Hancock Tower, Chicago

KK100, Shenzhen

Bank of China, Hong Kong

Aldar HQ (2011) MZ Architects

3. The Module

THE MODULE This chapter will examine the relationship between the size of the module, height of the building and efficiency and form. This will build upon current optimization research that is based on numerical studies but include a comparative study of the many projects that will be included in this book to look at how the module influences and responds to: - structural efficiency - height/width and proportion of the building - choice of fenestration pattern and window size - floor to floor heights - geometry of the building - eccentric loading - AESS versus concealed steel structures

Hearst Tower, NYC

Bow Encana, Calgary

Capital Gate, Abu Dhabi

Guangzhou IFC (2010) Wilkinson Eyre

4. Node and Member Design

NODE AND MEMBER DESIGN This chapter will examine the design of the members and nodes including material choices and why the majority of diagrids seem to select steel over concrete. The discussion will include: - the relationship with the module - function of prefabrication - the benefits of modularity - dealing with odd shapes and eccentricities as well as many one-of elements - the function of the stiffness of the node during erection - transportation - selection of the diagrid members - when custom fabrication is required - the impact of the choice to use AESS on the design of these elements

Capital Gate, Abu Dhabi

Al Bahar Towers, Abu Dhabi

Bow Encana, Calgary

Al Bahar Towers (2012) Aedas Architects

5. Core Design

CORE DESIGN This chapter will examine the reasons for choosing steel or concrete for the core based on considerations of: - constructablity - erection sequencing - local practices or preferences - fire protection and disaster mitigation issues - structural stability - dimensional characteristics of the building design - impact of and resistance to eccentric loading Included will be some discussion regarding a change in core design to reflect terrorism. Regions that might historically have used all steel buildings have more recently changed to composite steel and concrete cores as an anti-terrorism measure.

Freedom Tower, NYC - steel with 3’ of concrete

Swiss Re, London - complete steel frame

Capital Gate - concrete to handle eccentric loading

Bow Encana (2012) Foster + Partners

6. Constructability and Erection Issues

CONSTRUCTABILITY AND ERECTION ISSUES This chapter will examine the issues surrounding constructing and erecting a diagrid: - how is constructing a diagrid different from other structural types? - how do choices in node design, member type and length as well as module size impact construction and erection - what are the particular site issues that are unique to diagrid construction - transportation issues associated with nodes and long members - stability during erection (size of member versus temporary shoring) Some of the issues here will reference back to the design of the core as it is used during the construction process as an answer to some erection issues.

ROM, Toronto - irregular diagrid

Hearst, NYC - regular diagrid

Orbit Tower, London - modular

Capital Gate (2011) RMJM Architects

7. The Impact of Exposure

THE IMPACT OF EXPOSURE ON DESIGN AND DETAILING ISSUES This chapter will examine the issues surrounding choices to use a concealed or architecturally exposed diagrid. Whether or not a diagrid is exposed or concealed there will be similar issues from an architectural design perspective regarding the tendency of the diagrid to dominate the design. There may be instances where the structural system needs to be less visually dominant as a function of the use of the space. Concealed Structural Steel - detailing of the node - choice of and preferences for members - impact of the module size on the choice of members for concealed steel - fire protection Architecturally Exposed Structural Steel - detailing of the node for exposure - choice of and preferences for members - impact of the module size on the choice of members for concealed steel - workmanship issues - finishes and fire protection - scale of exposed systems - when the diagrid dominates the space

Guangzhou IFC - AESS

Capital Gate, UAE - AESS

London GLA - AESS

Capital Gate (2011) RMJM Architects

8. Cladding and Façade Treatment

CLADDING AND FAÇADE TREATMENT This chapter will examine the envelope related issues. The geometry of the façade will be impacted by: - the size of the module - the planimetric shape of the building - the planar vs sculptural three dimensionality of the building - desire to include natural ventilation - placement of the structural diagrid (inside or outside the envelope) - function of the building (use and partitions) Triangulated Glazing - when to use - incorporation of natural ventilation Rectilinear Glazing - when to use - cost issues - incorporation of natural ventilation Double Façades - how are diagrids used to create double façades - what are the merits (this will be a brief introduction to the topic as it is covered in detail in the next chapter) Intermediary Structures - use of lattice grids to span or complement diagrid structural systems Other practical issues such as the window washing and maintance will also be addressed. SIPG Tower, Shanghai - double façade | triangulated

CCTV, Beijing - rectilinear

Guangzhou IFC - super transparent glass

Shanghai International Port Group Tower (2008)

9. Exterior Diagrids

EXTERIOR DIAGRIDS This chapter will examine the choice to place the diagrid on the exterior of the thermal envelope. This has been done to support a double facade system or in climates that are temperate and where thermal bridging is not of concern. Double Façade - structural benefits of an external diagrid over a rectilinear system - impact on glazing and ventilation - constructability Exterior Diagrid Structure - why place on the exterior? - weathering issues - potential structural concerns - potential thermal concerns

Shelley Street, Sydney - Exterior

Hospital, Abu Dhabi - Exterior, double façade

O14, Dubai - Exterior concrete

Canton Tower (2010)

10. Architectural Applications

ARCHITECTURAL APPLICATIONS This chapter of the book will be the largest chapter and look to compare different “classifications” or “applications” of diagrid structures. This will be different than the reference to the projects in Chapters 2 to 9 where the method of diagrid design was explored. The following classifications will be used as a method of sorting the projects: - Tall and Supertall versus mid-rise applications - Curved geometries - Crystalline geometries - Eccentric loading vs. normalized loading - Hybrid diagrid buildings This section will work towards creating a series of more detailed project profiles of each of the subject buildings, including the following documentation: - Detailed close-up shots of exterior and interior - Photo or drawing of the nodes - Structural axonometric of the building (preferably a Tekla/BIM model) - Construction images (if available) - Descriptions of the way the diagrid system has been incorporated into the design. The level to which the project profiles can be consistently developed will be a function of the ability to source additional materials from the architects, engineers and fabricators. It is the intention of the Project Profiles to use as much “ready made” material that would have formed a part of the design and construction process. It is not my intention to commission new drawings.

Aldar HQ, Abu Dhabi

Guangzhou IFC Hotel Atrium

Hearst Tower Atrium

Arcelormittal Orbit Tower (2012)

11. Current State of Diagrid Research

CURRENT STATE OF DIAGRID RESEARCH This chapter will summarize the findings of the book and speak to what is being done in current research including mention of projects that are presently either “on the boards” or in the early stages of construction. Most of the published research is highly numeric and directed at University engineering research. It is my sense that much of the “real research” is being done in the engineering and architectural offices associated with these projects. Where academia is looking for optimization, practice seems geared towards innovation and the breaking of records.

Canadian Museum for Human Rights, Winnipeg

Al Bahar Towers, Abu Dhabi

Diagrid building, Auckland

Expose Diagrids Rev

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