affects of core design on space efficiency of high rise buildings

EFFECTS OF CORE DESIGN AND FORM ON

RENTABLE SPACES OF A HIGH RISE OFFICE

BUILDING

KESHAV ANAND / 2008BARC051

TENTH SEMESTER

GUIDE: Ar. SANDEEP ARORA

DEPARTMENT OF ARCHITECTURE

SCHOOL OF PLANNING AND ARCHITECTURE

BHOPAL

MAY 2013

EFFECTS OF CORE DESIGN AND FORM ON RENTABLE SPACES OF A HIGH RISE OFFICE BUILDING

Keshav Anand 2008BARC051 Page 1

DECLARATION

This is to certify that the Seminar entitled "The relationship between Structural System, Core

and rentable spaces of a high rise office building." submitted by me is a record of my own work

carried out under the supervision of Ar. Sandeep Arora. The matter embodied in this seminar

work, other than that acknowledged as reference, has not been submitted for the award of any

degree or diploma in this or any other institute.

School of Planning and Architecture (Keshav Anand)

Bhopal.

May - 2013

CERTIFICATE

It is certified that the declaration given above by Keshav Anand regarding his Seminar work is

true to the best of our knowledge.

Ar. Sandeep Arora Dr. Savita Raje

Seminar Guide, Head of the Department,

Department of Architecture, Department of Architecture,

School of Planning and Architecture, School of Planning and Architecture,

Bhopal Bhopal



ACKNOWLEDGEMENTS

I am grateful to my mentor Ar. Sandeep Arora sir and my friends for the support with which they

reviewed the original manuscript; and for conversations that clarified my thinking on this and

other matters. Their friendship and professional collaboration meant a great deal to me. They

provided me with material and spiritual support at critical and opportune times. A number of

students graciously allowed me to use some of their material as illustrations and examples. In

this regard, I am indebted to them. My mentor encouraged me to revise and improve the

manuscript. I anticipate that they all are satisfied with the outcome. I am grateful to my seminar

coordiantors Ar. Aarti Grover maam, Dr. Rachna Khare maam and Dr. Anand Wadwekar for

letting me choose this topic. Finally I thank my family for their constant and unconditional love.

School of Planning and Architecture Keshav Anand

Bhopal.

May 2013



Table of Contents DECLARATION ............................................................................................................................ 1 CERTIFICATE ............................................................................................................................... 1 ACKNOWLEDGEMENTS ............................................................................................................ 2 Table OF Figures ............................................................................................................................ 5 ABSTRACT .................................................................................................................................... 6 1. INTRODUCTION ................................................................................................................... 7 2. DESIGN CONSIDERATIONS FOR HIGH-RISE OFFICE BUILDINGS ............................ 8

2.1. FLOOR SLAB SHAPE AND SIZE ................................................................................. 8 2.2. LEASING DEPTH ......................................................................................................... 10 2.3. FLOOR TO FLOOR AND FLOOR TO CEILING HEIGHTS ..................................... 10 2.4. CORE CONFIGURATION ........................................................................................... 11 2.5. STRUCTURAL SYSTEM ............................................................................................. 12

3. BUILDING CORE DESIGN AND ITS EFFECTS ON RENTABLE SPACES .................. 13 3.1. CORE LOCATION ........................................................................................................ 14

3.1.1. Central Core ............................................................................................................ 14 3.1.2. Off- Set Core ........................................................................................................... 16 3.1.3. Split Core ................................................................................................................ 16 3.1.4. Exterior Core ........................................................................................................... 18

3.2. Lease Space Planning ..................................................................................................... 20 3.2.1. The Perimeter Office ............................................................................................... 20 3.2.2. The Executive Core................................................................................................. 21

4. STRUCTURAL SYSTEMS OF TEN TALLEST OFFICE BUILDINGS IN THE WORLD (CTBUH, 2008): LITERATURE CASE STUDIES ..................................................................... 21

4.1. Taipei 101 tower, Taipei ................................................................................................ 22 4.2. Shanghai world financial center, shanghai ..................................................................... 23 4.3. Petronas Towers 1&2, Kuala Lumpur ............................................................................ 23 4.4. Sears/Willis Tower, Chicago.......................................................................................... 24 4.5. Jin Mao Tower, Shanghai ............................................................................................... 25 4.6. Two International Finance Centre, Hong Kong ............................................................. 26 4.7. CITIC Plaza, Guanhgzhou ............................................................................................. 27 4.8. Shun Hing Square, Shenzen ........................................................................................... 27 4.9. Central Plaza, Hong Kong .............................................................................................. 28 4.10. Bank of China Tower, Hong Kong ............................................................................. 28



5. COMPARISON OF STRUCTURE, FORM AND SPACE EFFICIENCY OF WORLDS TALLEST OFFICE BUILDINGS ................................................................................................ 29

5.1. Taipei 101 tower, Taipei ................................................................................................ 29 5.2. Shanghai world financial center, Shanghai .................................................................... 29 5.3. Petronas Towers 1&2, Kuala Lumpur ............................................................................ 30 5.4. Sears/Willis Tower, Chicago.......................................................................................... 30 5.5. Jin Mao Tower, Shanghai ............................................................................................... 31 5.6. Two International Finance Centre, Hong Kong ............................................................. 31 5.7. Bank Of China Tower, Hong Kong ............................................................................... 32

6. CONCLUSION AND PREFERABLE DESIGN CONSIDERATIONS FOR HIGH RISE OFFICE BUILDINGS. ................................................................................................................. 33 Bibliography ................................................................................................................................. 36



Table OF Figures Figure 1: Square Floor slab (SEV & Aydan 2009) ........................................................................ 9 Figure 2: Hexagonal floor slab (SEV & Aydan 2009) ................................................................... 9 Figure 3: Irregular floor slab (SEV & Aydan 2009) ..................................................................... 10 Figure 4: Rectangular floor Slab with high aspect ratio (SEV & Aydan 2009) ........................... 10 Figure 5: Central Core configuration (SEV & Aydan 2009) ........................................................ 12 Figure 6: Split Core configuration (SEV & Aydan 2009) ............................................................ 12 Figure 7: Exterior core configuration (SEV & Aydan 2009) ....................................................... 12 Figure 8: A typical floor Plate and its elements ............................................................................ 14 Figure 9: Central core ................................................................................................................... 15 Figure 10: Offset Core location and unequal leasing spaces ........................................................ 16 Figure 11: Split core with access corridor in center ..................................................................... 17 Figure 12: Split core divided into four with access corridor in center .......................................... 18 Figure 13: Single exterior core ..................................................................................................... 19 Figure 14: Cores on either side of floor plate ............................................................................... 19 Figure 15: The Perimeter office arrangement ............................................................................... 20 Figure 16: The executive office arrangement ............................................................................... 21 Figure 17: Mega columns and outrigger trusses in Taipei 101 ..................................................... 22 Figure 18: Typical floor plan of Taipei 101 (SEV & Aydan 2009) .............................................. 22 Figure 19: Skeleton of WFC Shanghai ......................................................................................... 23 Figure 20: Typical floor plan Shanghai WFC (SEV & Aydan 2009) ........................................... 23 Figure 21: Typical floor plan Petronas towers (SEV & Aydan 2009) .......................................... 24 Figure 22: Floor Configuration of Sears Tower ........................................................................... 24 Figure 23: Typical Floor plan of Sears tower ................................ Error! Bookmark not defined. Figure 24: Typical floor Plan of Sears Tower ............................... Error! Bookmark not defined. Figure 25: Typical Floor plan Jin Mao Tower (SEV & Aydan 2009) .......................................... 25 Figure 26: Typical Floor Plan of Two International Finance Centre (SEV & Aydan 2009) ........ 26 Figure 27: Typical Floor Plan of CITIC plaza (SEV & Aydan 2009) .......................................... 27 Figure 28: Typical Floor Plan Shun Hing Square ......................................................................... 27 Figure 29: Typical Floor plan Central Plaza ................................................................................. 28



ABSTRACT

A high rise structure primarily consists of two components i.e. The Structural system and the

core. Although the rentable spaces or habitable spaces in a high rise building are a result of

geometry of floor plates and their vertical stacking which gives the form to the building.

Different geometries of floor plates and form of high rise structures requires specifically

designed structural system and core design to give the required structural strength and stability to

the building. Understanding the relation between these three components is inevitable in order to

find a space efficient and structurally sound solution for high rise office buildings. This seminar

discusses the various forms, core design and their spatial effects on rentable spaces and space

efficiency of the building. The seminar also compares the design and space efficiency of ten

tallest office buildings in the world and lists out the design considerations for a space efficient

high-rise office building.



EFFECTS OF CORE DESIGN AND FORM ON

RENTABLE SPACES OF A HIGH RISE OFFICE

BUILDING

1. INTRODUCTION

In the late nineteenth century, early tall building developments were based on economic

equations increasing rentable area by stacking office spaces vertically and maximizing the

rents of these offices by introducing as much natural light as possible.

High-rise office buildings, which are developed as a response to population growth, rapid

urbanization and economic cycles, are Indispensable for a metropolitan city development.

Given the high land values in central business sections of our leading cities, the skyscraper is

not only the most efficient, but the only economic utilization of certain strategic plots. An

exhaustive investigation.., has conclusively demonstrated that the factors making for diminishing

returns in the intensive development of such plots are more than offset by the factors making for

increasing returns... (Klaber 1930).

This statement holds true for today; however, the relationship between cost

and benefit is more complex in todays global marketplace. The current trend for

constructing office buildings is to build higher and higher, and developers

tend to compete with one another on heights. Tenants also appreciate a

landmark address and politicians are conscious of the symbolic role of high-rise buildings.

Nonetheless high-rise office buildings are more expensive to construct per square meter, they

produce less usable space and their operation costs are more expensive than

conventional office buildings. The space efficiency, as well as the shape and

geometry of the high-rise building need to satisfy the value and cost of the

development equation. Space efficiency, which is determined by the size of



the floor slab, dimension of the structural elements and rationalized core,

goes along with the financial benefit.

By the end of 1990s, at more than 30 stories, net to gross floor area ratios of 70-75% were

common in office buildings (Davis & Everest 1997). However net-to-gross floor area should not

be less than 75%, while 80% to 85% is considered appropriate (Yeang 1995). Wherever the tall

building is being constructed, achieving suitable space efficiency is not easy, since it is adversely

affected by height as core and structural elements expand to satisfy the requirements of vertical

circulation and resistance to lateral loads. Space efficiency can be increased by the lease span,

which is defined as the distance between the core and exterior wall.

2. DESIGN CONSIDERATIONS FOR HIGH-RISE OFFICE BUILDINGS

Architectural and structural requirements are the basic decision making parameters in the design

of high-rise office buildings, and the floor slab size and shape, leasing depth, structural frame,

floor-to-floor height, vertical transportation and core layout dictates the space efficiency of a

high-rise building.

2.1. FLOOR SLAB SHAPE AND SIZE

An office buildings floor slab size and shape have great impact on the space efficiency and the

buildings external character. The first aim is to achieve the maximum space efficiency and in

order to accomplish this task, initially the floor slab shape and total floor area of the building

need to be designed.

The space efficiency of a high-rise office building can be achieved by maximizing the Gross

Floor Area (GFA) and Net (usable) Floor Area (NFA) and in order to enable the developer and

owner to get maximum returns from the high cost of land, the floors must have sufficient

functional space (Kim H 2004).

The floor slab efficiency of a typical high-rise office building should generally not he less than

75%, unless the site is too small or too irregular to permit a higher level of space efficiency.



Floor slab designs using clever devices, such as scissor stairs, pressurized lift shafts, dispersal of

toilets etc. can increase efficiency up to 80% - 85 % per typical floor.

The floor slab shape also has a vital importance as well, since it influences the interior space

planning, layout of office equipment, exterior building envelope, structural system and

component sizes, utilizing from natural light and air, access to escape routes, etc. Generally the

more simple and regular the floor slab shape is, the easier it is to respond to user requirements in

terms of space planning and furnishing. Square, circular, hexagonal, octagonal and similar plan

forms are more space efficient than the rectangular plans with high aspect ratios and irregular

shapes. Buildings with symmetrical plan shapes are also less susceptible to wind and seismic

loads (J 1991). There is an obvious aim that the contemporary office buildings must be designed

with minimum or no interior columns to enable maximum flexibility, consequently a column-

free floor slab from the exterior to the core is the optimum solution for the office development.

Figure 1: Square Floor slab (SEV & Aydan 2009)

Figure 2: Hexagonal floor slab (SEV & Aydan 2009)

More Space Efficient

More Space Efficient



Figure 3: Irregular floor slab (SEV & Aydan 2009)

Figure 4: Rectangular floor Slab with high aspect ratio (SEV & Aydan 2009)

2.2. LEASING DEPTH

Leasing depth or lease span is the distance of the usable area between the exterior wall and the

fixed interior element, such as the core or the multi-tenant corridor. The leasing depth depends

on the functional requirements and is closely related with the structural frame of the building.

Smaller core-to-exterior window dimensions allow the users to maintain a relationship with the

outside, thus benefiting from the natural light. the depth of lease span must be between 10.0 and

14.0 m for office functions, except where very large single tenant groups are to be

accommodated (Ali M & Armstrong 1995). Large leasing depths require interior columns which

reduces the flexibility of the rentable floor space.

2.3. FLOOR TO FLOOR AND FLOOR TO CEILING HEIGHTS

The floor-to-floor height of an office building is typically the same for all occupied floors except

for the lobby and floors for special functions. In high-rise office buildings, additional floor-to-

floor height significantly entails greater cost on structural elements, cladding, mechanical risers,

and vertical transportation. Commercial functions require a variety of floor-to-ceiling heights

Less Space Efficient




ranging between 2.7 and 3.7 m and the depth of the structural floor system varies depending on

the floor loads, size of structural bay, and type of floor framing system (Ali M & Armstrong

1995).

2.4. CORE CONFIGURATION

The core of the building comprises all of the vertical circulation elements, such as elevators, fire-

stairs, mechanical shafts, toilets, and elevator lobbies. In early office buildings, these elements

tended to be dispersed on the floor rather than concentrated, while todays contemporary

buildings include all these elements in a specific zone, which is mainly the core. Many of the key

structural elements, such as the shear walls that provide lateral stability, are integrated into the

core in order to simplify the architectural design.

Layout of the core is critical to the development efficiency and operational effectiveness of a

high-rise office building, while also playing a significant role in the way the structure copes with

lateral loads (Watts, Kalita L & Maclean M 2007). Building cores can be arranged in several

ways. Central cores integrating with the outer structure resist lateral loads more effectively and

open up the perimeter for light and view, enabling efficient workplaces. Buildings with side

cores have the advantage of homogeneous workplaces, which is usually organized into one

space. Multiple cores are common in low-rise buildings, which have very large or narrow floor

slabs. The design of the core significantly affects the overall space efficiency of the buildings,

vertical circulation, and distribution of mechanical and electrical shafts. The lifting strategy

drives the core size and has a major impact in terms of design on all high-rise office buildings. In

order to achieve the maximum space efficiency of a high-rise office building, the core must be

reduced to an acceptable ratio of the gross floor area, while coping with the fire regulations and

achieving an effective vertical transportation with the elevators.



Figure 5: Central Core configuration (SEV & Aydan 2009)

Figure 6: Split Core configuration (SEV & Aydan 2009)

Figure 7: Exterior core configuration (SEV & Aydan 2009)

2.5. STRUCTURAL SYSTEM

For contemporary high-rise office buildings, it is important to adopt a structural system to

provide an open-plan, in which all office workers perform in a common space. Several structural

solutions have been developed and are combined to meet the architectural requirements, such as

column-free spaces and maximum leasing depth allowed by the site regulations. In 1969 Fazlur

Most Space Efficient


Least Space Efficient



Khan classified structural systems for high-rise buildings according to their height. Later, he

upgraded these diagrams and developed schemes for both steel and concrete. The structural

systems for high-rise buildings are divided into two broad

categories, which are interior and exterior structures (Ali M M & Moon KS 2007). This

classification is based on the distribution of the components of the primary lateral load-resisting

system over the building.

A system is categorized as an interior structure, when the major part of the lateral load resisting

system is located within the interior of the building. Likewise, if the major part of the lateral load

resisting system is located at the building perimeter, this system is categorized as an exterior

structure. The two basic types of interior structures are the moment-resisting frames and shear

trusses/walls. These systems are usually arranged as planar assemblies in two principal

orthogonal directions and may be employed together as a combined system in which they

interact. Another important system in this category is the core-supported outrigger structure,

which is very widely used for super high-rise buildings. Unlike the interior structures, such as

moment-resisting frames or shear walls are concentrated in a zone like the core, it is inevitable to

achieve the maximum space efficiency. In the exterior structures category, tubular systems,

which can be defined as a three-dimensional structural system utilizing the entire perimeter to

resist lateral loads, are the most typical. Widely spaced framed tube, braced tube, tube-in-tube

and bundled tube are the sub categories of this structural system (Taranath 1998). Since the

tubular wall at the perimeter of the tower resist the entire lateral load, the interior floor slab is

kept relatively free of core bracing and large columns, thus increasing the net leasable area of the

building. A recent type of the exterior structures is the diagrid system. Diagrid structures, with

their structural efficiency, are also effective in providing an aesthetic character to the building.

Other types of exterior structures include space trusses, super frames and exoskeletons (Ali M M

& Moon KS 2007). These systems are effective in resisting to both lateral and gravity loads, thus

enabling the maximum space efficiency.

3. BUILDING CORE DESIGN AND ITS EFFECTS ON RENTABLE SPACES

The typical floor plate of the standard commercial office structure contains the following:



Vertical Circulation Core

Open Lease Space

Optional public corridor.

Figure 8: A typical floor Plate and its elements

3.1. CORE LOCATION

The Building Core can take any of basic locations relative to the floor plate.

Central Core

Off- set Core

Exterior Core

Split Core

3.1.1. Central Core

When the core is present in the geometrical center of the floor plate it is called as the central

core. In the central core the lease depth is relatively equal around the core of the building. The

Tenant can lease the entire floor plate or the tenant can lease a portion of the floor plate.



Figure 9: Central core Advantages and limitations of Central core:

Provides equidistant circulation for users and services

Offers equal modules of rentable spaces.

Offers natural light from all four sides.

Offers column free and flexible spaces on entire floor plate.



3.1.2. Off- Set Core

The off Set-Core places the core off center creating differing lease depths. This provides more

but unequal leasing options.

Figure 10: Offset Core location and unequal leasing spaces Advantages and limitations of offset core:

Do not provide equidistant circulation for users and services

Offers unequal modules of rentable spaces.


Offers greater number of leasing options.

Depending upon the leasing depth and structural system, the part with greater leasing

depth need not provide column free spaces.

3.1.3. Split Core

The Split core divides the core with a central space; all components of the core are accessed from

this central space. This eliminates the need for any peripheral access corridor and lease space can

extend right up to the walls of the core elements. The Split Core can be divided in any number of



ways. It should be noted that this increases the depth of the core and therefore the size of the

floor plate. The lease area can here too be divided but access must still be maintained to two

means of egress in case of fire.

Figure 11: Split core with access corridor in center

Advantages and limitations of offset core:

Provides equidistant circulation for users and services

Offers equal modules of rentable spaces.


Depending upon the leasing depth and structural system may provide column free spaces.

Due to two or more cores the requirement of services increases. Two cores require two

numbers of fire escape staircases.



Figure 12: Split core divided into four with access corridor in center

3.1.4. Exterior Core

In the Exterior Core configuration the core is pulled either to one side or edge. If the core is

pushed to one side creating a dead wall this can be used to advantage where poor views or

party walls present a problem. The Core can also be isolated as a separate mass element

independent from the lease floor plate.



Figure 13: Single exterior core

Figure 14: Cores on either side of floor plate



3.2. Lease Space Planning

Lease space can be arranged in basically two general configurations:

Perimeter Office Executive Core

3.2.1. The Perimeter Office

In the perimeter office, private managerial offices line the outside wall of the building. Their

views make them prime locations. The corners of the building are then the most sought after.

These are often reserved for the highest staff level. The buildings corners can be properly

utilized to create more corner offices.

Figure 15: The Perimeter office arrangement



3.2.2. The Executive Core

Increasingly we see the introduction of the executive core which moves the executive offices to

the center of the floor plate. This allows greater light penetration and maximizes the number of

people who get a view.

Figure 16: The executive office arrangement

4. STRUCTURAL SYSTEMS OF TEN TALLEST OFFICE BUILDINGS IN THE

WORLD (CTBUH, 2008): LITERATURE CASE STUDIES The space efficiency of a building is a result or outcome of the structural system and form of the

building. The structural system and form are directly related to each other as different forms can

be achieved with different structural systems. A comparison of structure system and form of the

ten tallest office buildings in the world will help in understanding the space efficiency of the

buildings.



4.1. Taipei 101 tower, Taipei

The building is supported by a mega-frame, which comprises eight mega-columns of size 2.4 m

x 3.0 m. These columns are boxes of 80 mm thick steel slabs filled with high-strength silica fume

concrete up to the 62nd floor. A multicellular core of braced steel, becoming massive reinforced

concrete shear walls below the 7th floor, is coupled to the fin columns with mega truss outriggers

at every eight floor. Within these box-like cells, secondary frames support office decks of

lightweight concrete on metal decking (Wells M 2005).

Figure 17: Mega columns and outrigger trusses in Taipei 101

Source: Emporis Buildings, Taipei 101, [online image] available from: http://www.emporis.com/building/taipei101-taipei-taiwan, accessed on 30/03/2013

Figure 18: Typical floor plan of Taipei 101 (SEV & Aydan 2009)



4.2. Shanghai world financial center, shanghai

The building is supported by three parallel and interacting

structures: (1) A Vierendeel moment resisting space frame,

consisting of fin columns, diagonals and the belt truss; (2)

Concrete core walls; (3) Outrigger trusses interacting between the

core walls and the mega columns of the space frame.

Figure 19: Skeleton of WFC Shanghai

Source: The Shanghai World Financial Center, [online image] available from: http://www.structuremag.org/article.aspx?articleID=393, accessed on 30/03/2012

Figure 20: Typical floor plan Shanghai WFC (SEV & Aydan 2009)

4.3. Petronas Towers 1&2, Kuala Lumpur

The structural system comprises a mega-frame of high-strength concrete columns and beams

interacting with a high-strength concrete shear core. The perimeter columns of 2.4 m diameter

and core walls are connected with composite girders and two-story high steel outrigger trusses at



four levels. Typical floors consist of wide flange beams spanning from the core to the ring beams

with a composite metal deck and concrete topping (Pelli & Crosbie 2001).

Figure 21: Typical floor plan Petronas towers (SEV & Aydan 2009)

4.4. Sears/Willis Tower, Chicago

The building is supported by a bundled-tube system comprising of

nine individual tubes of 22.9 m x 22.9 m. As the tower climbs upward,

the tubes drop off at the 50th, 66th and 90th floors. The columns of

each tube are spaced at 4.6 m. The structure also has diagonal bracing

only on the mechanical levels before each setback. The structural floor

system comprises composite wide flange beams with a 7.6 cm

composite metal deck with 6.3 cm light-weight concrete topping floor

slab (Taranath 1998).

Figure 22: Floor Configuration of Sears Tower

Source: Council on Tall Buildings and Urban Habitat,1995, [Diagram]. In: Structural Systems for Tall Buildings, McGraw Hill Book Co. - Singapore



Figure 23: Typical Floor Plan of Sears Tower

4.5. Jin Mao Tower, Shanghai

A central reinforced concrete core linked to exterior composite megacolumns (up to 5x16ft) by

outrigger trusses are the primary components of the structural system. A central shear-wall core

houses the primary building functions. The outrigger trusses are located between three different

levels. The truss between the levels 85 and 87 is capped with a three-dimensional steel space.

Maximum Wind Speed is 125 mph at the top.

The tower is built around a central octagonal concrete surrounded by 8 exterior composite super

columns and eight other steel, including outdoors. Three sets of 8 half-high, two levels,

connecting the columns at the center, in six of the floors, to

provide additional support.

Each of its 88 floors are divided into 16 segments, each one

eighth shorter than the level achieved in the base 16.

The advanced structural system that has been used in its

construction allows it to withstand winds up to 200 km / h

and earthquakes up to 7 on the Richter scale. The needle of

the top supports a range of 75 cm and its vertical deviation

is only 2 cm. Figure 24: Typical Floor plan Jin Mao Tower (SEV & Aydan 2009)



The shafts are steel joints that act as bumpers to cushion the lateral forces imposed by winds and

earthquakes, and pool on the floor 57 acts as a passive damper. Steel bars provide structural

support for the glass dome of the entries. 1062 The foundations rest on piles of high strength

steel being 83.5 meters deep to compensate for poor conditions of the upper layers of soil. At

that time these were the longest steel piles used in the construction of a building.

The wall surrounding the basement is 1 m thick, 36 m high and 568 m long, consisting of 20.500

m of reinforced concrete complex external aluminum The exterior curtain wall is made of glass,

stainless steel, aluminum, and granite, and is crossed by a complex latticework cladding made of

aluminum alloy tubes.

4.6. Two International Finance Centre, Hong Kong

The building is supported by a large high-strength reinforced concrete core and eight perimeter

composite mega-columns, which are encased in high-strength concrete and linked to the core by

story-height steel outrigger trusses at four levels.

Figure 25: Typical Floor Plan of Two International Finance Centre (SEV & Aydan 2009)



4.7. CITIC Plaza, Guanhgzhou

The structural system is a tube-in-tube structure comprising twenty high-strength reinforced

concrete perimeter columns, spandrel beams and a reinforced concrete central core. The inner

and outer tube is linked with the floor beams and slabs.

Figure 26: Typical Floor Plan of CITIC plaza (SEV & Aydan 2009)

4.8. Shun Hing Square, Shenzen

The building is supported by a peripheral rigid steel frame and reinforced concrete central core,

which is linked to the outer frame by rigid steel outriggers at four levels. Structural floor system

comprises closely spaced steel beams and one-way spanning slabs.

Figure 27: Typical Floor Plan Shun Hing Square



4.9. Central Plaza, Hong Kong

The building is supported by a high-strength concrete tube-in-tube system comprising perimeter columns at 4.6 m on centers and spandrel beams 1.1 m deep. The triangular-shaped core concentrates the reinforced concrete shear walls carrying approximately 10 % of the total wind shear. The structural floors are conventional with primary and secondary beams carrying metal decking with 16 cm thick reinforced concrete slab.

Figure 28: Typical Floor plan Central Plaza

4.10. Bank of China Tower, Hong Kong

The structural system is a cross-braced space truss comprising four concrete encased steel mega-

columns at building corners with a size of 4.3 m x 7.93 m, and single column at the center above

25th floor. This structural scheme supports lateral loads as well as the entire weight of the

building. The structural floor comprises steel beams spanning between composite core walls and

exterior frame carrying the steel slabs and 12 cm concrete topping (Taranath 1998).

Figure 29: Typical plan of Bank of China



5. COMPARISON OF STRUCTURE, FORM AND SPACE EFFICIENCY OF WORLDS TALLEST OFFICE BUILDINGS

The above discussed buildings can be compared in terms of their design considerations to analyze the space efficiency of the buildings.

5.1. Taipei 101 tower, Taipei

Figure 30: Typical Floor plan Taiepei 101 (SEV & Aydan 2009)

5.2. Shanghai world financial center, Shanghai

Figure 31: Typical floor plan Shanghai WFC (SEV & Aydan 2009)

Central Core gives maximum space efficiency. Exterior columns provide column free rentable

spaces. Corner recessions provide good performance

against winds. 8 mega columns reduce the flexibility of

interior spaces. Tapering of building gives varying leasing

depths at different floors ranging from 13.9-9.8 mts.


spaces. Equal and flexible rentable spaces.



5.3. Petronas Towers 1&2, Kuala Lumpur

Figure 32: Typical floor plan Petronas towers (SEV & Aydan 2009)

5.4. Sears/Willis Tower, Chicago

Figure 33: Typical floor Plan of Sears Tower

Central Core provides equidistant circulation. Exterior columns provide column free rentable

spaces and invite natural light from all sides. Irregular geometry of the floor plate creates

limitations in divisibility of rentable spaces. The geometry of floor plate in combination

with square central core gives poor space efficiency.

The space efficiency of the floor plate is least among tallest office buildings.

Central Core provides equidistant circulation. Interior columns limit the flexibility of

rentable spaces but provide greater stability. Due to introduction of interior columns greater

leasing depth has been achieved and is the most space efficient building in the list.



5.5. Jin Mao Tower, Shanghai

Figure 34: Typical Floor plan Jin Mao Tower (SEV & Aydan 2009)

5.6. Two International Finance Centre, Hong Kong

Figure 35: Typical Floor Plan of Two International Finance Centre

Varying leasing depths due to chamfered profile of floor plate.

Chamfered profile of core corresponding the chamfered profile of floor plate gives more space efficiency.


spaces. Corner recessions provide good performance

against winds. 8 mega columns reduce the flexibility of

interior spaces. Different profiles of floor plate and core

makes it less space efficient.



5.7. Bank Of China Tower, Hong Kong

Figure 36: Bank of China Tower, Hong KOng

Table 1: Comparison of areas and space efficiency of world's ten tallest office buildings

S.No Name of Building

Height

GFA (m2)

NFA (m2)

Interior Columns

Location of Core

Leasing Depth

Core Integrity

Space Efficiency (%)

1 Taipei 101 Tower

509 2650 1920 No Center 13.9-9.8 No 72

2 Shanghai WFC 492 2500 1750 No Center 12.5 Yes 70 3 Petronas

Tower 1-2 452 2150 1290 No Center 13.0-8.3 No 60

4 Sears Tower 442 4900 3780 Yes Center 22.9 No 77 5 Jin Mao Tower 421 2800 1940 No Center 14.8-

11.8 No 69

6 Two International Finance Center

415 2800 1904 Yes Center 14.5 Yes 68

7 CITIC Plaza 391 2230 1500 No Center 11.3 No 67 8 Shun Hing

Square 384 2160 1450 No Center 12.5-

12.0 No 67

9 Central Plaza 374 2210 1460 Yes Center 13.5-9.4 Yes 66 10 Bank of China 367 2704 1865 No Center 17.6 No 69 Average 12.1 69.5

Two split cores require additional service

requirements. Spaces between two cores do not receive

natural light. Less space efficient due to inflexible rentable

space.



6. CONCLUSION AND PREFERABLE DESIGN CONSIDERATIONS FOR HIGH RISE OFFICE BUILDINGS.

The following are the major conclusions of the research:

Structural system and core configuration are the most important factors affecting the space

efficiency of high-rise office buildings, as they are closely related with the shape of the floor

slab, leasing depth, floor height and vertical transportation. Cores in high-rise office

buildings are much more complex than in conventional buildings, and their design is

fundamental to the development and the operational effectiveness of a tower. Key elements

of the core are the structural elements and elevators while the lifting design is the major

determinant of the core size and the space efficiency, and it determines the occupant travel

and maximum waiting times. By the input of a specialist, dividing a building into a number

of zones, each served by an appropriate sized group of lifts to decrease the core size, will

increase the space efficiency. The use of sophisticated controls for elevators is also an

effective way of minimizing the number of elevators and waiting periods.

Depending on requirements of the clients or the tenants, areas of the core elements can vary

significantly, affecting the space efficiency. The ratio of core to gross floor area is inversely

proportional to the space efficiency. The vertical transportation elements, such as elevators

and fire stairs require more analysis for more economic and efficient solutions of the floor

plans in conjunction with the construction of high-rise office buildings.

Central core approach is commonly used for high-rise office buildings. The cores are

interconnected with the main structural frame, thus resisting a substantial amount of the

lateral loads in all examples, without exception. This interconnection between the core and

the structural frame is provided by the structural floor system and steel outrigger trusses.

Utilization of steel outrigger trusses is necessary for super tall high-rise office developments

to improve the efficiency of structural system and achieve greater heights.

The two common structural systems for the tallest office buildings of the world are

composite mega-columns and central core with outriggers, and reinforced concrete tube-in-

tube without outriggers system. Either steel or concrete structures are used; however, high-

strength concrete is more common due to its lower cost, compared with steel.



6.1. Preferred geometry for the building

As we concluded that buildings with regular geometric shapes like square, rectangle, circle triangle gives maximum space efficiency. The shape of the floor slab is derived from a basic equilateral triangle.

The corners of the triangle have been chamfered keeping the wind considerations in mind as chamfered corners behave better against wind loads than the sharp edges.

6.2. Core configuration

Central core is used in the design for the number of benefits mentioned earlier. The shape of the core is adjusted to get equal and right angles for better planning of the core.

The central core is then split into three following the three sides of the triangular shape. The split central core does not require any circulation corridor around the core and provides equidistant circulation of users as well as services.



6.3. Structural system

Shear wall core with peripheral columns provide column free flexible rentable spaces. The leasing depth is kept between 12- 14 meters to avoid the need of interior columns.

6.4. Space efficiency of the floor.

Gross floor area = 2183 sq.m.

Net floor area = 1704 sq.m.

Leasing depth = 11.6- 15.8 m.

Space efficiency = 78%

The achieved space efficiency is even more than the compared list of ten tallest office buildings. The use of exterior columns and central-split core is main deciding factor for the design.



Bibliography Ali M M & Moon KS 2007, 'Structural Developments in Tall Buildings:Current Trends and Future Prospects,', Architectural Science Review, pp. 205-23.

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Davis , L & Everest 1997, High-Rise Office Towers - Cost Model, viewed 15 april 2013, .

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SEV, A & Aydan, O 2009, 'SPACE EFFICIENCY IN HIGH-RISE OFFICE BUILDINGS', Faculty of Architecture, METU, Turkey.

Taranath, B 1998, Steel, Concrete and Composite Design of Tall Buildings, McGraw-Hill, Inc., New York.

Watts, Kalita L & Maclean M 2007, 'The Structural Design of Tall and Special Buildings', in The Economics of Super-Tall towers.

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Yeang, K 1995, The Skyscraper, Bioclimatically Considered, Academy, London.

cover page_Keshav.pdfKESHAV ANAND / 2008BARC051

Seminar_Keshav Anand.pdfDECLARATIONCERTIFICATEACKNOWLEDGEMENTSTable OF FiguresABSTRACT1. INTRODUCTION2. DESIGN CONSIDERATIONS FOR HIGH-RISE OFFICE BUILDINGS2.1. FLOOR SLAB SHAPE AND SIZE2.2. LEASING DEPTH2.3. FLOOR TO FLOOR AND FLOOR TO CEILING HEIGHTS2.4. CORE CONFIGURATION2.5. STRUCTURAL SYSTEM

3. BUILDING CORE DESIGN AND ITS EFFECTS ON RENTABLE SPACES3.1. CORE LOCATION3.1.1. Central Core3.1.2. Off- Set Core3.1.3. Split Core3.1.4. Exterior Core

3.2. Lease Space Planning3.2.1. The Perimeter Office3.2.2. The Executive Core

4. STRUCTURAL SYSTEMS OF TEN TALLEST OFFICE BUILDINGS IN THE WORLD (CTBUH, 2008): LITERATURE CASE STUDIES4.1. Taipei 101 tower, Taipei4.2. Shanghai world financial center, shanghai4.3. Petronas Towers 1&2, Kuala Lumpur4.4. Sears/Willis Tower, Chicago4.5. Jin Mao Tower, Shanghai4.6. Two International Finance Centre, Hong Kong4.7. CITIC Plaza, Guanhgzhou4.8. Shun Hing Square, Shenzen4.9. Central Plaza, Hong Kong4.10. Bank of China Tower, Hong Kong

5.1. Taipei 101 tower, Taipei5.2. Shanghai world financial center, Shanghai5.3. Petronas Towers 1&2, Kuala Lumpur5.4. Sears/Willis Tower, Chicago5.5. Jin Mao Tower, Shanghai5.6. Two International Finance Centre, Hong Kong5.7. Bank Of China Tower, Hong Kong

6. CONCLUSION AND PREFERABLE DESIGN CONSIDERATIONS FOR HIGH RISE OFFICE BUILDINGS.6.1. Preferred geometry for the building6.2. Core configuration6.3. Structural system6.4. Space efficiency of the floor.

Bibliography

affects of core design on space efficiency of high rise buildings

Documents

architecture bhopal

rentable spaces

anand wadwekar

seminar work

sandeep arora sir

seminar coordiantors

savita raje seminar

table of contents declaration