[RC] Chapter 1

1. Determining all applied forces acting in the structure.

2. Balancing the safety, economy, and practicability/aesthetic of all structural members.

In designing a structure, two general steps are deemed necessary. What are those two steps?

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John Smeaton (1760)

The first recorded use of concrete in modern times.

He used the lock wall on the river Calder in Britain made of stone and filled with concrete.

How did John Smeaton utilize the use of concrete?

Joseph Aspdin (1824)

The English bricklayer who obtained the patent for cement is?

Joseph Louis Lambot (1854)

This French inventor built a rowboat made of concrete with a parallel wires network as reinforcements.

Joseph Monier (1867)

A Frenchman who invented reinforced concrete and received a patent for constructing concrete basins or tubs and reservoirs with wire mesh or iron wire as the reinforcement.

Thaddeus Hyatt (1877)

He found that both concrete and steel behave homogeneously after experimenting for the flexural test in 50 reinforced concrete beams with iron bars as tension reinforcements.

Working Stress Design (WSD)

Thaddeus Hyatt’s assumption on concrete has been proven important in designing a concrete using elastic theory. The design principle in which this was used was:

Charles S. Whitney (1942)

The most adapted design philosophy was introduced by this American Civil Engineer. Wherein he replaced the assumption of a linear stress distribution in WSD with the average stress.

Prestressed design

The reinforced concrete was further developed by introducing pre-compression in the tension area to reduce cracks. This development was the introduction of a?

Ultimate Strength Design (USD) in 1963

The American Concrete Institute (ACI) Code has specified the use of what design principle and in what year?

Working Stress Design (WSD)

It is also known as the Alternate Stress Design or Straight-line Design

Ultimate Strength Design (USD)

It is also known as the Strength Design.

Working Stress Design (WSD)

It is a method of designing reinforced concrete in which concrete is assumed to be elastic.

Working Stress Design (WSD)

This design principle is based on elastic theory where the concrete and steel act together elastically in which the stress-strain relationship is linear and within the proportional limit based on Hooke’s Law.

Ultimate Strength Design (USD)

It is a method in which structural elements are evaluated at their ultimate failure state. This method acknowledges the nonlinear behavior of concrete and steel and the importance of applying the factor of safety in proportion to the degree of uncertainty for specific materials’ loading conditions.

National Structural Code of the Philippines (NSCP)

This has been the primary structural design code in the country since its first edition un 1972.

National Structural Code of the Philippines (NSCP)

This code provides guidance to civil and structural engineers when designing and assessing buildings and other structures, particularly in considering the application of loads dye to natural disasters.

American Concrete Institute (ACI) Code

This code is a standard of the American Concrete Institute and one reference code in NSCP.

American Concrete Institute (ACI) Code

This code is partly a specification-type code that determines the proper methods for testing, inspection, and building code requirements.

American Concrete Institute (ACI) Code

It exhibits the minimum design requirements consistently with good safety considerations and reasonable provisions considering the accountability in the economy criterion of structural design.

fc (0.45 fc’)

The allowable compressive stress of concrete.

fc’ (21 MPa, 25 MPa, 28 MPa)

The specified compressive strength of concrete at 28 days curing

23\.54 kN/m3

Unit weight of concrete

Ec = 4700 sqrt(fc’)

The modulus of elasticity of concrete.

The allowable tensile stress of steel.

fs (0.5 fy)

fy (275 MPa, 345 MPa, 414 MPa)

The yield stress of steel.

Beam or Girder

It is one of the main structural members in the building structure with long, horizontal, or inclined members and is limited in width and depth.

Beam

Its main purpose is to support loads from the slab.

Girder

Its main purpose is to support loads from the beam and the slab.

Slab

It is a horizontal plate structural member in the building floor or roof . Its depth is relatively small compared to its length or width.

Column

This member is the most critical structural member in the building.

Column

This member is subjected to axial loads or axial loads and moments.

Column

It supports the loads from the slab and beam/girder.

Footing

This member is located below the natural grade soil.

Footing

Its shape is typically in pads or strips that support the column member and spread its loads immediately to the ground.

Design

It is a type of problem in which service loads are given and directly applied in the structure.

Design

This type of problem aims to determine the appropriate size of concrete and the number and sizes of steel reinforcements needed in structural design elements.

Investigation

It is a type of problem in which structural elements have dimensions or sizes and have complete details for the steel reinforcements.

Investigation

This type of problem is integrated with structural analysis to evaluate the capacity of the structure in order to draw conclusion (safe or unsafe) when the service loads and natural loads are applied.

77\.01 kN/m3

Unit Weight of Steel

200 000 MPa

Modulus of Elasticity of Steel

Crushing of Concrete

This failure occurs when the compressive stress of concrete reaches the allowable compressive stress.

Yielding of Steel

This failure is initiated by steel reinforcement when the tensile stress of steel reaches the allowable tensile stress.

Simultaneous Crushing of Concrete and Yielding of Steel

This refers to the balance failure of concrete and steel in which the compressive stress of concrete reaches the allowable compressive stress, and at the same time, the tensile stress of steel reaches the allowable tensile stress.

Balanced Design

This design refers to the proportioned design in which the maximum stresses in concrete and steel are reached simultaneously, causing both concrete and steel to fail at the same time.

Balanced Design

This type of design’s failure is caused by the simultaneous crushing of concrete and yielding of steel.

Under-reinforced Design

The failure in this design is initiated by yielding the steel reinforcement.

Under-reinforced Design

It is a design in which steel reinforcement is less than the required for balanced conditions because when the ultimate load will be reached, the steel begins to yield while the compression of concrete is still under-stressed.

Under-reinforced Design

The failure under this condition is ductile and will give warning to the user in the structure before its collapse.

Over-reinforced Design

The failure in this design is initiated by crushing of concrete.

Over-reinforced Design

It is a design in which steel reinforcement is more than the required for the balanced condition and the steel reinforcement will not yield before failure.

Safety

It is the most important criterion in designing reinforced concrete.

Safety

This criterion provides guaranteed stability in the structure when loads are applied.

Economy

It is the second important criterion in designing reinforced concrete.

Economy

This refers to the least dimensions of concrete and less usage of steel reinforcements in the structural members without compromising the structural safety considering the financial aspect criterion.

Practicability or Aesthetic

It is the last criterion to be considered in designing reinforced concrete.

Practicability or Aesthetic

The structure must be evaluated based on the principle underlying this criterion.

6, 10, 12, 16, 20, 25, 28, 32, 36

Standard Bar Diameters

Grade 33 (230 MPa)

White

Grade 40 (275 MPa)

Yellow

Grade 60 (420 MPa)

Green

Weldable

Red