Topic : Common Structural Forms for High-rise Buildings in Hong Kong

Topic : 

Common Structural Forms for 

High-rise Buildings in Hong Kong 

Prepared by Raymond Wong

Building bends or deflects 

under lateral force 

wind 

The more rigid of a building 

structure, the less it deflects 

Deflection is a comfort 

consideration for building 

users. Building regulation 

has a basic criteria on 

deflection. 

The structure of a building 

should be so designed to 

have a deflection less than 

1/500 of its height 

The problems of tall 

and slim building

Various deflection modes under wind tunnel test

Structural forms suitable for buildings in HK 

1. Column and beam (framed) structure in RC 

sometimes called framed buildings which are structures 

formed by the framed elements usually in the form of 

columns and beams, as well as further strengthened as 

necessary by the introduction of rigid floor membranes and 

external walls. 

- Simple formwork is required 

- lower cost of construction 

- easy to satisfy various spatial arrangement and shapes 

- may not be very able to cater for the structural needs of 

tall and slim buildings 

- more suitable to construction low-rise or horizontalspread 

buildings such as schools, podium or carpark 

structures

Example of 

layout design 

evolution from a 

5 x 3 grid system

Example of In-situ RC frame building


2. Load bearing wall (shear wall) structure in RC 

- More complicated formwork is required 

- cost of construction may increase especially for 

building with more internal walls or in complicated 

shape 

- the load bearing walls can strengthen the rigidity of the 

building and able to resist building against deflection 

- building examples: public buildings such as the 

Harmony Blocks

Example of load-bearing 

wall structures


3. Load bearing wall plus core wall structure 

- Complicated formwork is often required especially in 

forming the core 

- cost of construction is higher, especially for buildings 

with complicated shape (e.g. lots of set-back or light 

wells 

- has very strong rigidity to resist deflection 

- this is the most common structural form for use in HK’s 

residential buildings due to: 

. walls between residential flats can be best used as a 

load bearing wall (fire resistance is one reason) 

. To fulfill building regulation for prescribed window 

areas 

. To satisfy the rigidity of high-rise buildings


wall structures with building 

area below 500 sq m

Example of load-bearing wall structures of 

building area around 800 – 1000 sq m


wall structures with 

several blocks linked 

together to form a 

connected structure

Structures in 

load-bearing wall 

with a RC core


4. RC Centre core plus a RC frame structure 

- Confine to more regularly shaped or building 

with simpler layout, such as usual tower type 

buildings 

- fair rigidity performance but may not be 

sufficient for building higher than, say 50 storeys. 

- rigidity can be improved by the adding in of 

other stiffening members 

- plenty of window areas (it is only a frame in the 

external face the building) 

- The internal core may have difficulty in getting 

natural ventilation or sunlight.

Example of 

cored structure 

with an external 

frame for towertype 

office 

building

Various layout arrangement 

for building using core and 

outer frame structure

Various layout arrangement 

for building using core and 

outer frame structure

It is sometimes quite 

difficult and costly to 

construct the RC core


5. Center core plus a outer core structure (tube in tube) 

- Formwork usually very complicated with the floor 

added in at a second stage 

- building shape confined to tubular forms 

- area of windows limited due to the provision of a 

structurally strong external tube (wall) 

- quite strong in rigidity and be able to construct to 

very tall structure 

- building examples – Hopewell Center (HK) or the 

previous World Trade Center in New York

Examples of tube-in-tube structures

Examples of a framing plan showing the location/layout of 

walls, columns and beams


6. Steel frame structure 

- building is lighter than usual RC structure due to the 

relative higher weight/strength ration of steel 

- construction cost is lower especially for buildings 

adopting high level of standardization 

- building is weak in rigidity due to steel is a more 

flexible (elastic) material when compare to RC 

- additional stiffening elements in the form of 

internal/external trusses, out-rigger or bracing members 

are often required to make the building structure more 

rigid 

- addition work is required to fire-protect the steel 

structure 

- building examples: The Center, China Bank Building

Examples of building constructed in pure structural steel frame

Construction of Structural steel frame building


7. Composite structure (RC Core plus steel frame, hybrid 

structure) 

- building can be lighter than usual RC structure but 

with a more acceptable rigidity than pure steel 

buildings 

- construction cost is higher for the adding in of a RC 

core which requires a complicated formwork system 

- it is time consuming and more complicated to make 

connections between the RC and steel elements 

- It is even more difficult and costly if stiffening 

members are introduced into the building in order to 

make it more rigid to resist deflection 

- Building examples: Time square, Manual Life Tower, 

Cheung Kong Center, IFC 1 and 2

Examples of composite structures

Complicated stiffening 

elements incorporated in 

steel or composite 

building to improve the 

rigidity of the structure 

The IFC 2

Outrigger system used 

in Cheung Kong Center 

Cheung Kong 

Center

Complicated stiffening elements 

incorporated in steel or composite 

building to improve the rigidity 

of the structure 

The Cheung Kong Center

Cost idea of using RC, Steel and composite 

method in constructing tall buildings

How to construct various forms of Buildings 

Buildings can be constructed or formed in a number 

of ways, such as: 

1. In-situ manner using formwork – for all 

reinforced concrete buildings 

2. Prefabricated manner – for using part or all in 

precast concrete elements 

3. Prefabricated manner – using structural steel 

elements 

4. Hybrid manner – making combination of any of 

the above systems

Construction of in-situ RC buildings 

Forming the wall structure 

using aluminum moulds 

Forming the wall structure using 

manual-type timber formwork


Forming the structure using large 

panel-type forms for walls or columns


Forming the wall structure using 

mechanical-operated formwork systems


Forming the floor structure using 

timber formwork systems


Forming the floor structure 

using table formwork – most 

suitable for office buildings


Forming the floor structure using 

table formwork – floor being 

strengthened by tensioning technique

Construction of prefabricated frame building 

Headquarters building of 

Hong Kong Jockey Club 

Podium – KCR 

Kowloon Station

Construction of prefabricated frame building 

Using precast elements as part of the 

external walls as well as the permanent 

formwork for load-bearing walls 

An external view of building – 

majority of external walls are 

constructed in precast manner

Advantageous features of framed structure 

1. Speedy construction due to simplicity in geometry – 

consist of only columns and beams (or partially by the 

floor slab) as the main structural elements 

2. Very rigid and stable – able to resist tremendous vertical 

(dead load) and lateral loads (wind) 

3. Reduced dead load – absent of thick shear wall etc. 

4. Roofed over at an earlier stage – every floor slab being 

finished becomes an cover to protect the lower floors from 

sun and rain 

5. Offer large unobstructed floor areas – without obstacle 

between columns 

6. Flexible utilization of space

Advan. . features of framed structure (continued) 

7. Adaptable to almost any shape 

8. Easily altered within limits of frame 

– regular or non-regular grid system is very adaptable in 

spatial arrangement 

9. Offsite preparation possible – especially for prefabricated 

construction using precast concrete or structural steel 

elements 

10. May be designed to accommodate movement 

11. Acceptable distribution of natural light – window openings 

can be provided easily on eternal walls 

12. Easy to design structurally including computer design – again, 

due to simple geometry

Principle factors affecting choice of frame 

Production consideration 

• Availability of materials, labour and plant 

• Speed of construction 

• Availability of mechanical plants 

Architectural Design consideration 

• Size and shape of site 

• Conditions of site 

• Integration of mechanical elements 

• Architectural or aesthetic requirements

Principle factors affecting choice of frame 

Structural Design consideration 

• Foundation consideration 

• Standardization of members or design 

• Span and floor loads 

• Fire resistance requirement 

• Maintenance consideration 

• Integration of architectural & structural elements

Features of In-situ concrete frame construction 

Construction aspects 

1. Insitu concrete is inconsistent in quality in performance – 

mixing, delivery, placing and compacting of concrete 

require very tight quality control 

2. Overlapping formwork, steel fixing and concreting 

process make site operations more difficult – these works 

are to be done almost at the same time at the same 

location 

3. Formwork erection is often timely, expensive, 

environmental unfriendly and labour intensive 

4. Increase a lot of wet-work – difficult to maintain site in a 

clean and tidy environment


Construction aspects – examples of problem 

Improper placing and compaction will 

serious lower the strength of concrete



Finishing the concrete surface after 

placing – improper finish will affect 

the size and dimension of member



Exterior environment 

Interior environment 

It is difficult to maintain a clean and tidy site using in-situ 

concrete structure for the casting process is wet and dirty

Features of In-situ RC frame construction 

Construction aspects (continue) 

5. Easier to allow for dimensional discrepancy – formwork 

can relatively easy to provide any ready dimension and 

shape 

6. Concrete is cheap, easy available and can be cast into 

complicated shape 

7. Frame erection affected seriously by climatic condition – in 

windy day it is difficult to erect formwork nor to place 

concrete 

8. Durability affect by heat, moisture or environmental 

factors – concrete is not so durable as most person think

Features of in-situ RC frame construction (cont.) 

Structural characteristics and design aspects 

1. Concrete design more flexible and accurate than steel 

because of non dependence on standard sections 

2. Concrete frame easily damaged by building movements 

3. Problems of creep & shrinkage (cause damage to finishes) 

4. Higher dead load and bigger structural elements 

5. Better fire resistance 

6. Durability sensitive to workmanship 

7. Overloading cause irreversible structural damages 

8. Flexible in layout and shape

Features of structural steel construction 

Structural characteristics 

1. Steel has lower dead load (unless encased in concrete) 

2. Steel frame can easily to have the layout changed to suit 

new design than concrete, especially requiring alteration 

after completion of the building. 

3. Easily accommodate building movements for steel is a 

relatively flexible material and have greater adaptability to 

take up strain and deformation 

4. However, it is weaker in fire resistance for steel will lose 

strength and deform serious at higher temperature (at 600oC 

or above). This can be improved by applying fire resistant 

plaster


Structural characteristics (continue) 

5. Beams usually shallower in size than for concrete Beams 

6. Sections in various convenient type and size thus 

economical in design and uses – refer to standard steel 

sections 

7. Produce larger deflection & deformation (Bend) under 

wind – this will cause uncomfort to users of building 

8. Steel has higher thermal expansion value 

9. Rusting or corrosion problems – very strict anti-corrosion 

treatment has to be applied

Features of structural steel construction (cont.) 


1. Quicker to erect and can be prepared offsite – in 

workshop/factory environment with good production and 

quality control 

2. Erection on site less affected by climatic conditions – 

without placing of concrete 

3. Longer and highly coordinated planning – require long time 

to make structural design, fabrication and delivery 

4. Higher requirement in the control of dimensional accuracy 

before and during construction (in fabrication and in 

erection

Features of structural steel construction (cont.) 


5. Demand greater transportation or cranages provision 

6. Complicated quality assurance procedures – especially in 

the control of welding connection 

7. Difficult to make connection with rigid structures – 

especially in composite structure in which RC core structure 

is involved 

8. More complex when building become more gigantic and 

taller – due to the huge number of structural members, some 

may be of very heavy section 

9. Induce more works at higher altitude


Construction aspects – highlight of some problems 

Delivery of structural steel 

member by ship 

Large member delivery to site 

waiting to hoisting up for erection



Hoisting of the structural steel 

member to the upper floor



Connecting steel members with RC 

element – an anchor frame may be 

required for making strong connection



Constructing the composite floor 

in steel/RC composite structure 

To connect floor to core wall – 

starter bars are to be provided 

within the core structure



Very large component often in 

complicated shape



Huge amount of structural members 

make erection very complicated



Very complex and gigantic framework as stiffening members 

to the overall structure – Belt truss system, the IFC II



Very complex and gigantic framework as 

stiffening members to the overall structure – 

Outrigger, Cheung Kong Center



The existence of very complicated jointing 

in steel structure



– highlight of some problems 

Required to perform works at 

very high altitude



Workers work at high altitude



Connecting large and complicate shaped 

components can be very difficult



Concrete has to be trimmed 

to allow steel to pass through 

Examples of location where unmatched dimension causing problem



Roof truss and 

the decking not 

on the same level 

Examples of location where unmatched dimension causing problem

Topic : Common Structural Forms for High-rise Buildings in Hong Kong

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