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تصميم المنشآت الخرسانية المسلحة
DESIGN OF REINFORCED
CONCRETE STRUCTURES
محمد إبراهيم الرجوب. د
Design Methods
Building Codes
Loads
Components of Concrete
Properties of Concrete
INTRODUCTION
INTRODUCTION
Materials
Concrete = FA + CA + cement +Water +Add.
= Agg. + Paste
Reinforced Concrete = Concrete + Steel
Why Steel is used??
Material Properties
Properties of Concrete
Ex. RC BEAMS
RC Beams
Water / Cement Ratio
w/c = 0.2 – 0.3 ???
w/c = 0.35 – 0.45 ???
Concrete Compressive strength
Typical Stress-strain curve of concrete
Curves of HSC vs NSC
Steel
Typical Stress-strain curve of steel
Prestressing
Steel:
stress-
strain
curve
Ec (SI Units)
Ec: (NWC and LWC)
Example USC Units
Tensile strength
Ft = (0.05 – 0.1) f’c
Types: 1. Modulus of rupture. 2. Split tensile strength
3. Double Punching . 4. Direct Tensile strength.
Modulus of Rupture (SI units)
SI units USCU
Tensile strength
Ft = (0.05 – 0.1) f’c
Types: 1. Modulus of rupture. 2. Split tensile strength
3. Double Punching . 4. Direct Tensile strength.
SI Units USCU
Modulus of
Rupture
Fr =
Split Tensile
Strength
Concrete Shrinkage
Effect of curing on Concrete Shrinkage
Concrete Creep
LOADS
DEAD LOADS
Dead loads are weights of material, equipment, or
components that are relatively constant throughout
the structure's life.
Permanent loads includes dead loads and forces set
up by irreversible changes in a structure's constraints
such as loads due to settlement.
Live loads: Sometimes referred to as probabilistic loads
include all the forces that are variable within the object's
normal operation cycle not including construction or
environmental loads.
Live loads (roof) produced (1) during maintenance by
workers, equipment and materials; and (2) during the life
of the structure by movable objects such as planters and
by people.
Live loads
Include:
People
Books
Equipment
LRFD or LFD General Form
ACI Partial Safety Factors
AISC LRFD Partial Safety Factors
Codes
Several Codes have recently been
revised to incorporate Probabilistic
design Such as
- ACI 318 -08 Building Code
- AISC LRFD Steel Manual
- BS 8110 -02
Loads (See ASCE Load ..)
Typical Dead Loads for common
building materials
ASCE Loading
Typical Live loads
ACI & AISC Load Factors
Load factors and Combinations
Example: Load Combinations (USCU)
Example 2:
Solution
LECTURE _2_
STRUCTURAL SYSTEM OVERVIEW
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One-Way Joist Floor System
2D lateral frames
Floor joists, type
Rib (joist) slab : (One-way bending)
2D gravity or lateral
frames
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One-Way Joist Floor System
Lateral space frame
Floor joists, type
Rib (joist) slab with beams: (One-way bending)
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One-Way Joist Floor System
• 2’ or 3’ cc. – Joists
• 4’ or 6’ cc. – Skip joists
• 5’ or 6’ cc – Wide-module joists
Top of Slab
1:12 Slope, type
8-24” for 30” Modules
16-24” for 53” Modules
14-24” for 66” Modules .
Width varies
4”, 6” or larger
(100-150 mm)
Typical Joist
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One-Way Joist Floor System
Advantages:
Longer spans with heavy loads
Reduced dead load due to voids
Electrical, mechanical etc. can be placed between voids
Good vibration resistance
Typical Applications:
Medium-to-long spans with heavy loading
For 30” modules, 35’ – 40’ spans
For 53” & 66” modules, 35’ – 50’ spans
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Two-Way Joist Floor System
2D lateral frames
Waffle pans, type
Waffle slab : (Two-way bending)
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Two-Way Joist Floor System
Advantages:
Longer spans with heavy loads
Reduced dead load due to voids
Electrical, mechanical etc. can be placed in voids
Good vibration resistance
Attractive Ceiling
Typical Applications:
Long spans with heavy loading
For 3’, 4’, and 5’ modules, 40’ – 50’ spans and beyond
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B. Lateral Load Systems
Frame Overview
Flat plate (& slab)-column (w/ and w/o drop panels and/or capitals) frame systems
Beam-column frame systems
Shear wall systems (building frame and bearing wall)
Dual systems (frames and shear walls)
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Frame: Coplanar system of beam (or slab) and
column elements dominated by flexural deformation
Planar (2D) Space (3D)
CVEN 444 Structural Concrete Design
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Basic Behavior
Gravity Load Lateral Loading
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Frame Advantages
Optimum use of floor space, ie. optimal for office buildings,
retail, parking structures where open space is required.
Relatively simple and experienced construction process
Generally economical for low-to mid-rise construction (less than
about 20 stories)
In Houston, most frames are made of reinforced concrete.
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Frame Disadvantages
Generally, frames are flexible structures and lateral
deflections generally control the design process for buildings
with greater than about 4 stories. Note that concrete frames
are about 8 times stiffer than steel frames of the same
strength.
Span lengths are limited when using normal reinforced
concrete (generally less than about 40 ft, but up to about 50
ft). Span lengths can be increased by using pre-stressed
concrete.
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Frame Lateral Load Systems
Flat plate-column frame:
Plan Elevation
Effective slab
width
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Frame Lateral Load Systems
Beam-column frame:
Elevation
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Frame Lateral Load Systems
For relatively square plans, diaphragms are generally considered rigid
Space frame with
square plan
Deformed shape has constant lateral
displacement - No diaphragm flexibility,
ie. lateral load distributes to frame
proportional to frame stiffness
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Shear Wall Lateral Load Systems
Shear wall
Elevation
Edge column
Interior gravity
frames
Shear deformations generally
govern
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Shear Wall Lateral Load Systems
Gravity frames
Shear walls
Coupling beams
Elevator shaft configuration
Hole
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Dual Lateral Load Systems
Lateral frames – 25%
of lateral load,
minimum
Shear walls
Wall-Frame Dual System:
Hole
Analysis Versus design
Analysis Versus design
AISC Loads