Main Functions of Buildings

1 / 16

# Main Functions of Buildings - PowerPoint PPT Presentation

Main Functions of Buildings Provide a safe and comfortable environment for work and rest. (Protect us from wind, rain and the wild animals) Two types of loads act on a building structure ： 1. Vertical force (Load from the weight of human, furniture or building itself) 2. Lateral force

I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.

## PowerPoint Slideshow about 'Main Functions of Buildings' - lotus

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.

- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript

Main Functions of Buildings

• Provide a safe and comfortable environment for work and rest. (Protect us from wind, rain and the wild animals)
• Two types of loads act on a building structure：

1. Vertical force

(Load from the weight of human, furniture or building itself)

2. Lateral force

(Load from wind or earthquake etc.)

• Basic requirements in building architecture：

1. For safety, a building will not collapse under great stress

2. For comfort, a building will not move excessively under great pressure

Stress
• Load acting on a structure will be shared by each component.

eg. For a load of 200,000 kg shared by 4 pillars, each

pillar has to bear 50,000 kg.

• Stress = Force/Area

In the above case, if the area increases and the load remains unchanged, the stress will decrease.

• The maximum stress that a material can bear is called the material strength.
Beam

L

• A component used to bear the bending forces in a structure.
• When stress is exerted, it has to bear a pressure from above and a pulling force from below. (see the figure above)
• Under constant load (W), if the beam’s span (L) increases, it’s vertical displacement will increase and the stress it bears will increase.
• The beam’s vertical displacement and stress will decrease if the thickness of the beam (H) increases.

H

W

Building Material

1. Timber：

• Light; cheap; easy to link up; has a high availability.
• Used for buildings of one or two levels (common in Europe and America).
• Low strength; easy to deform under stress or pressure; cannot be used in tall buildings or long bridges.

2. Steel bar：

• High strength; high resistance to deformation; suitable for constructing tall buildings and long bridges.
• Expensive
• Difficult to link up (components are prepared in factory, rather in the building site.)
Steel-reinforced Concrete
• Concrete can bear a very high pressure but is weak in bearing tension.
• Steel lines are used to bear tension.
• Cheaper than steel bars.
• Can apply directly in working place; can be made into components for combination.
Building Structure
• Vertical Force
• Passes from the floor to the beam, then to the pillar, and finally to the base.
• Lateral Force
• The framework can bear the lateral force.
• A shear wall is added to the structure of building with over twenty levels and thus the building can bear a greater lateral force.
A higher building suffers a greater lateral force, and therefore a tall building has to face a much greater lateral force than the vertical force.
• Buildings having 40 to 50 levels (or more) require special designs :

1. Reduce the distances between the pillars and thicken the beams.

=>To increase the structural efficiency.

However, when the structural efficiency maximizes, the frame will become a box with many small holes on it.

eg. Jardine House

2. Super Frame

- Most of the external forces are taken by the super-sized structural components.

eg. Hong Kong and Shanghai Bank Building

Acknowledgment：
• Hong Kong University of Science and Technology (HKUST)
• Dr. Christopher K.Y. LEUNG Associate Professor, Department of Civil Engineering, Hong Kong University of Science and Technology