BT 5 - 02 Concrete Constrcution Systems

Cast-In Place

• In situ or at the site utilizing temporary formworks.

• Also referred to as "poured-in-place" This is the preferred choice for foundations, slabs, columns, beams, walls, roofs, etc.

Egyptians

Concrete, on its earlier forms were used to build the pyramids since the time of the _________ 5000 years ago

Romans

The ______ used a remarkable material close to the modern cement to build many of their architectural marvels during the period of 300 BC to 476 AD.

Ingalls Building

The _______ was the first concrete high rise that was built in Cincinnati, Ohio in 1903.

Thomas Edison

________ designed and built the first concrete homes in Union, New Jersey in 1908.

Assembly Hall

The first concrete domed sports arena, known as the __________, was built at the University of Illinois in 1963.

Chicago, Illinois

The tallest reinforced concrete building was built in _________. This 65-story building is known only by its street address, 311 South Wacker Drive

Concrete Cylinder Test

• Done to determine the compressive strength of concrete

  • Conducted every 7, 14, and 28 days

65-75% of 28-day strength

Typical development pattern: 7 Days — Strength

85-90%

Typical development pattern: : 14 Days — Strength

Design stretch achieved

Typical development pattern: : 28 Days — Strength

28-day

Engineers use early break results to predict______ performance.

2,500-3,000 psi

For residential slabs. How many psi (pounds per square inch)?

3,000-4,000 psi

For sidewalks and driveways. How many psi (pounds per square inch)?

4,000-5,000 psi

For commercial slabs. How many psi (pounds per square inch)?

5,000-8,000 psi

For structural columns and beams. How many psi (pounds per square inch)?

10,000 psi and above

For high-performance concrete. How many psi (pounds per square inch)?

Slump test

Done to determine the workability of concrete

6-8 inches

Acceptable slump range

Precast Concrete

Also known as "Prefabricated"

• The concept of this technology is standardizing & mass producing from a plant outside of the project site.

Residential buildings

_______ using precast concrete is usually 5-10 stories in height.

Joseph Monier

After his invention of reinforced concrete, the invention of precast concrete elements was made because prefabrication has great advantages compared with in-situ concrete.

John Alexander Brodie

Precast panelled buildings were pioneered in Liverpool, England and invented by city engineer.

Gosvenor Atterbuy 

Who used a similar technique in the houses he built at Forest Hills Gardens. Houses that utilized approximately 170 precast panels each.

Ernst May

Who have made use of panelized prefab concrete system in a number of notable housing done in Frankfurt.

National Precast Concrete Association

Specialized in precast concrete products industry focusing on utility, underground & other non-prestressed products.

Precast/Prestressed Concrete Institute

Precast concrete structures industry on prestressed concrete elements and on other precast concrete elements used in above-ground structures such as buildings, parking structures, and bridges.

Lattice girder

This was used for precast products, which was the starting point for the industrial production of precast elements on a broad basis.

Large Panel Systems

This refers to multi-storey structures composed of large wall and floor concrete panels connected in the vertical and horizontal directions.

• Form a box-like structure 

Cross-wall system

The main walls that resist gravity and lateral loads are placed in the short direction of the building.

Longitudinal-wall system 

The walls resisting gravity and lateral loads are placed in the longitudinal direction

Precast frames

Can be constructed using either linear elements or spatial beam-column sub-assemblages.

Precast beam-column sub-assemblages

Have the advantage that the connecting faces between the sub-assemblages can be placed away from the critical frame regions.

Linear elements

Generally preferred because of the difficulties associated with forming, handling, and erecting spatial elements.

Slab-Column Systems with Walls/ Mixed

These systems rely on shear walls to sustain lateral load effects, whereas the slab-column structure resists mainly gravity loads.

Lift-slab system with walls

This load bearing structure consists of precast reinforced concrete columns and slabs. These are assembled using special joints.

Prestressed slab-column system

The slab panels are lifted to the top of the column and then moved downwards the final position.

• The precast concrete column elements are 1 to 3 storeys high.

• Uses horizontal prestressing in two orthogonal directions' to achieve continuity.

Pre-Stressed Concrete

It is a method for overcoming concrete’s natural weakness in tension. It can be used to produce beams, floors or bridges with a longer span than with ordinary reinforced concrete

Pre-stressing tendons

Used to provide a clamping load which produces a compressive stress that balances the tensile stress that the concrete compression member would otherwise experience due to a bending load

Traditional reinforced concrete

_________ is based on the use of steel reinforcement bars or rebars inside poured concrete.

John Roebling and Sons

In early 1900 to 1950, the company _______ developed the first stress-relieved wire followed by the first stress-relieved strand

Pre-tensioned concrete

Cast around steel tendons (cables or bars) while they are under tension.  The concrete bonds to the tendons as it cures, and when the tension is released it is transferred to the concrete as compression by static friction. 

anchoring points

Pre-tensioning requires strong, stable ________ between which the tendons are to be stretched

Pre-tensioned elements

________ may be incorporated into beams, balconies, lintels, for slabs or piles.

1. Formworks

2. Reinforcement Bars

3. Concrete Pouring

What is the sequence of Cast In Place?

High tensile steel tendons

Prestressed Concrete — Provide a clamping force that creates compression.

bending

The compression helps a balance tensile stress caused by _________.

Bonded Post-Tensioned

Tendons are stressed after concrete cures, then grouted inside ducts

Unbonded Post-Tensioned

Tendons remain unbonded and can move locally relative to the concrete

Rainscreen System

Ventilated airspace behind exterior cladding for moisture management

Architectural concrete

Decorative and functional concrete walls/panels

Fiber Cement Siding

Durable, low maintenance, resistant fire , insects and rot.

GFRC (Glass Fiber Reinforced Concrete)

Lightweight, strong, moldable exterior cladding material

Cavity Wall

Two masonry/concrete wythes separated by an air space

ICF (Insulating Concrete Forms)

Interlocking insulated forms creating highly insulated concrete walls

Pre-Tensioning

• Tendons — stretched between strong anchoring points

  • Cast around the tensioned tendons

Post-Tensioning

Concrete is cast with rebar and steel cable/strand reinforcement

• Two techniques: Bonded and Unbonded

Unbonded and Bonded

What are the two techniques of post-tensioning?

Bonded Technique

Tendon is place in a duct; grout is injected after stressing.

Example: In bridges/transportation and can be used in buildings

Unonded Technique

Tendon is protected with grease and plastic sheathing and remains unbonded.

Example: Used for slabs, beams, transfer girders, joists, shear walls, and mat foundations