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    Lesson 1 Introduction To RC Design

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    rose ann claveria
    1) Reinforced concrete is a combination of concrete and steel where steel provides tensile strength to concrete which only has compressive strength. 2) The objectives of reinforced concrete design are for the structure to be appropriate, economical, structurally adequate, and maintainable. 3) Loads on structures include dead loads which are constant and live loads which can change and include wind, rain, earthquakes, and temperature effects. Load combinations must be considered in design.

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    Lesson 1 Introduction To RC Design

    Uploaded by

    rose ann claveria
    99 views6 pages
    1) Reinforced concrete is a combination of concrete and steel where steel provides tensile strength to concrete which only has compressive strength. 2) The objectives of reinforced concrete design are for the structure to be appropriate, economical, structurally adequate, and maintainable. 3) Loads on structures include dead loads which are constant and live loads which can change and include wind, rain, earthquakes, and temperature effects. Load combinations must be considered in design.

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    Lesson 1 Introduction to RC Design

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    1) Reinforced concrete is a combination of concrete and steel where steel provides tensile strength to concrete which only has compressive strength. 2) The objectives of reinforced concrete design are for the structure to be appropriate, economical, structurally adequate, and maintainable. 3) Loads on structures include dead loads which are constant and live loads which can change and include wind, rain, earthquakes, and temperature effects. Load combinations must be considered in design.

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    © All Rights Reserved
    Download as PDF, TXT or read online from Scribd
    Download as pdf or txt
    99 views6 pages

    Lesson 1 Introduction To RC Design

    Uploaded by

    rose ann claveria
    1) Reinforced concrete is a combination of concrete and steel where steel provides tensile strength to concrete which only has compressive strength. 2) The objectives of reinforced concrete design are for the structure to be appropriate, economical, structurally adequate, and maintainable. 3) Loads on structures include dead loads which are constant and live loads which can change and include wind, rain, earthquakes, and temperature effects. Load combinations must be considered in design.

    Copyright:

    © All Rights Reserved
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    Download as pdf or txt
    of 6

    University of Southeastern Philippines

    Bislig Campus
    Maharlika, Bislig City

    Lesson 1: Introduction to Reinforced Concrete Design

    Objectives:
    1. Identify the characteristics and components of a reinforced concrete.
    2. Identify the advantages and disadvantages of reinforced concrete as a structural material.
    3. Identify the four main criteria in the design of reinforced concrete.
    4. Apply the process of analysis and design of reinforced concrete structures.

    Activity/Analysis

     What conditions dictate the use of reinforced concrete structures?


     How would you make representations of real world structures in for analysis and
    design or reinforced concrete structures?
     What structural loads would you consider in the analysis and design of reinforced
    concrete structures?
     What load combinations should you use in your analysis and design of reinforced
    concrete structures?
     How would you select the governing forces for the design of any structural elements
    of a reinforced concrete structure?

    Introduction

    To understand and keep abreast with the design requirements of reinforced concrete as well as to
    engage safely in innovative design, the engineer needs a thorough grounding in the fundamental
    performance of concrete and steel as structural materials and in the behavior of reinforced concrete
    members and structures. Civil engineers need to design structures safely, economically, efficiently,
    and fully compliant with the governing building and structural codes. A civil engineer needs to have
    technical knowledge on the characteristics, process of analysis and design procedures of any
    structural element of reinforced concrete. Thus, the following topics will be covered.

    Abstraction

    Concrete is a mixture of sand and gravel held together with a paste of cement and water.
    Sometimes one or more admixture is added to change certain characteristics of the concrete such as
    its workability, durability, and time of hardening. Concrete has a high compressive strength and a
    very low compressive tensile strength.

    Reinforced concrete is a combination of concrete and steel wherein the steel reinforcement
    provides the tensile strength lacking in the concrete. Steel reinforcement is also capable of resisting
    compression forces and is used in various structural elements of reinforced concrete structures.
    1

    Module 1: Design & Analysis of Beams, T-Beams, and One-Way Slab


    University of Southeastern Philippines
    Bislig Campus
    Maharlika, Bislig City

    Reinforced concrete design can be understood if its numerous advantages and disadvantages
    are considered. These include the following:

    Advantages of Reinforced Concrete as Structural Material


     It is a low maintenance material.
     It has great resistance to the action of fire provided that there is adequate cover over the
    reinforcing steel.
     A special nature of concrete is its ability to be cast in to a variety of shapes from simple slabs,
    beams, and columns to great arches and shells.
     A lower grade of skilled labor is required for erection as compared to other materials such
    as structural steel.
     In most areas, concrete takes advantage of inexpensive local materials (sand, gravel, and
    water) and requires a relatively small amount of cement and reinforcing steel.

    Disadvantages of Reinforced Concrete as Structural Material


     Concrete has a very low tensile strength, requiring the use of tensile reinforcing.
     Forms are required to hold the concrete in place until it hardens sufficiently. Formwork
    could be expensive.
     The properties of concrete could vary widely due to variations in its proportioning and
    mixing. Furthermore, the placing and curing of concrete is not as carefully controlled, as is
    the production of other materials such as structural steel.
     In general, reinforced concrete members are relatively large, as compared to structural steel
    members

    Objectives of Reinforced Concrete Design

    The structure should satisfy four (4) major criteria:


    1. Appropriateness. The arrangement of spaces, spans, ceiling heights, access, and traffic
    flow must complement the intended use. The structure should fit its environment and be
    aesthetically pleasing.
    2. Economy. The overall cost of the structure should not exceed the client’s budget.
    Frequently, teamwork in design will lead to overall economies.
    3. Structural Adequacy. Structural adequacy involves two major aspects.
    a) A structure must be strong enough to safely support all anticipated loadings.
    b) A structure must not deflect, tilt, vibrate, or crack in a manner that impairs its
    usefulness.
    4. Maintainability. A structure should be designed to require a minimum of maintenance and
    to be able to be maintained in a simple fashion.

    Process of Analysis and Design

    1. Idealization of the structure into loadbearing frames and elements for analysis and design.
    2. Estimation of loads.
    3. Analysis to determine the maximum moments, thrusts and shears for design.
    4. Design of sections and reinforcement arrangements for slabs, beams, columns and walls
    using the results from step 3.
    5. Production of arrangement and detail drawings and bar schedules.
    2

    Module 1: Design & Analysis of Beams, T-Beams, and One-Way Slab


    University of Southeastern Philippines
    Bislig Campus
    Maharlika, Bislig City

    Structural Elements and Frames

    The complete building structure can be broken down into the following elements:

    Beams – horizontal member carrying lateral loads


    Slabs - horizontal plate elements carrying lateral loads
    Columns - vertical members carrying primarily axial load but generally
    subjected to
    axial load and moment
    Walls - vertical plate elements resisting vertical, lateral or in-plane loads
    Bases and foundations – pads or strips supported directly on the ground that spread the
    loads from

    Reinforced concrete
    building elements

    Slab and
    Module beam system
    1: Design in a building
    & Analysis Typical
    of Beams, T-Beams, andreinforced
    One-Way concrete
    Slab structural framing system
    University of Southeastern Philippines
    Bislig Campus
    Maharlika, Bislig City

    LOADS

    The most important and most critical task of an engineer is the determination of the loads that can
    be applied to a structure during its life, and the worst possible combination of these loads that might
    occur simultaneously. Loads on structure may be classified as dead loads or live loads.

    Dead Load
    Dead loads are loads of constant magnitude that remain in one position. This consists mainly of the
    weight of the structure and other permanent attachments to the frame.

    Live Load
    Live loads are loads that may change in magnitude and position. Live loads that move under their
    own power called moving loads. Other Live loads are those caused by wind, rain, earthquakes, soils,
    and temperature changes. Wind and earthquake loads are called lateral loads.
    Arrangements of Live Load
    Live loads may be applied only to the floor or roof under consideration, and the far ends of columns
    built integrally with the structure may be considered fixed. It is permitted by the code to assume the
    following arrangement of live loads:
    a) Factored dead load on all spans with full factored live load on two adjacent spans, and
    b) Factored dead load on all spans with full factored live load on alternative spans.

    Load combinations and load factors when designing reinforced concrete

    Required strength U:

    Dead load (D) and live load (L)


    U = 1.4D + 1.7L

    Combination of D, L, and W (Wind load)


    U = 0.75(1.4D + 1.7L + 1.7W)
    U = 0.9D + 1.3W

    Combinations of D, L and E (Earthquake load)


    U = 1.1D + 1.3L + 1.1E
    U = 0.9D + 1.1E

    Earth pressure H is included in design


    U = 1.4D + 1.7L + 1.7 H

    Note: Select the maximum effect of the applicable load combinations for the structure under consideration.

    References: Nilson, et. al. (2016), MacGregor, and Wight (2012), and McCormac and Nelson
    (2006), NSCP (2010).
    4

    Module 1: Design & Analysis of Beams, T-Beams, and One-Way Slab


    University of Southeastern Philippines
    Bislig Campus
    Maharlika, Bislig City

    Application

    Using the load combinations, determine the ultimate axial force and bending moment combinations
    for the column CD at point C. The frame is subjected to the following working loads:
    D = 15 kN/m (uniform)
    L = 30 kN/m (uniform)
    Wind load of 95 kN (may act in either direction) (MacGregor and Wight, 2012)

    Structural analysis results:

    How to select forces governing the design?


    Consider the max. and min. ultimate axial
    force on the column and the max. and min.
    ultimate bending moment at C:
    The section must be designed to withstand:
    1. an axial compression force of -207 and a
    bending moment of -161.9)
    2. axial force -188.2, and bending -196.6
    3. axial force -17.6, and bending +36.4

    Reference:
    MacGregor, and Wight (2012)
    5

    Module 1: Design & Analysis of Beams, T-Beams, and One-Way Slab


    University of Southeastern Philippines
    Bislig Campus
    Maharlika, Bislig City

    REFERENCES:

    Association of Structural Engineers of the Philippines (2010). The National Structural Code of the
    Philippines, 6th Ed. Panay Ave., Quezon City: ASEP.

    Gillesania (2004). Fundamentals of Reinforced Concrete Design, 2nd Ed. Cebu City, Philippines

    McCormac and Nelson (2014). Design of Reinforced Concrete, 7th Ed. USA: John Wiley & Sons,
    Inc.

    MacGregor, J. G., and Wight, J. K. (2012). Reinforced Concrete, Mechanics & Design. 9th ed.,
    Pearson Education, Inc.

    Nilson, A. H., Darwin, D., and Dolan, W. (2016). Design of Concrete Structures. 15th ed.,
    McGraw Hill.

    Module 1: Design & Analysis of Beams, T-Beams, and One-Way Slab

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