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27 Cards in this Set
- Front
- Back
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Mention advantages of using concrete as construction material |
1. Fire resistance more than wood and steel 2. Economy because its low maintenance cost 3. Give any shape so it’s suitable for architecture requirements 4. Durable if designed and laid properly |
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Numerate limitations or disadvantages of using concrete as construction material |
1. Weak in tension and cracks when subjected to tensile stress 2. Shrinks and sets up shrinkage stresses 3. Not completely impervious 4. Takes time to attain its full strength 5. Needs a lot of formwork and skilled labour |
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State the purposes of providing reinforcement in the RCC |
1. To take up all tensile stresses developed in structure 2. Increase the strength of the concrete 3. Prevent propagation of cracks developed due to temperature and shrinkage stresses 4. To make the section thinner as compared to the plain concrete section |
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Numerate Suitability of steel as reinforcing material |
1. It’s durable, cheap and easily available 2. Develops a good bond with concrete 3. Strong in compression, tension, shear and torsion 4. Has a longer lofe |
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5. Explain important factors that combination of concrete and steel |
1. The bond between concrete and steel 2. Prevention of concrete of steel bars embedded in the concrete 3. Thermal expansion of both concrete and steel |
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6. List advantages of reinforced concrete |
1. Resistance to affects of fire and water 2. Uses local material for aggregate 3. A long service life 4. Low maintenance cost 5. Architectural flexibility |
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7. List disadvantages of reinforced concrete |
1. Quality control is difficult 2. Forms are require to hold the concrete until it hardens 3. Heavy load of concrete 4. Formwork is expensive |
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Factors affecting selection of slabs |
Varying conditions and stipulations ask for the selection of appropriate and cost-effective concrete slab, keeping in view, the type of building, architectural layout, aesthetic features, and the span length. |
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Types of slabs |
• Concrete slabs, therefore, are further classified into: 1. Solid slab, 2. Flat slab, 3. Hollow core slab, Hollow Precast slab 4. Precast slab, 5. Prestressed slab (Post tension slab) 6. Ribbed or Waffle slab, 7. Hollow block slab (Hourdi), Rib & block slab 8. Composite slab. |
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Advantages, disadvantages and application of solid slabs |
Advantages 1. Easy to construct. 2. It does not require skilled labours 3. Easy to install electrical, mechanical and plumbing services 4. The formwork are simple Disadvantages 1. Becomes very deep for higher loads 2. During the curing period, the formwork cannot be removed. 3. The concrete in the tension zone has no structural performance but it is provided to simplify the construction. Application: Multistory buildings, framed residential apartments etc. |
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1. What is meant by the Limit States? |
• Limit state: A condition at which a structure or some part of structure ceases to perform its intended function. • Limit state is the border between desirable and undesirab performance • When a structure or part of it becomes unfit for its intends use, it is said to have reached a limit state |
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2. List the groups of limit states then define each of them |
1 - Ultimate Limit States (ULS ) •Ultimate limit states (ULS) concern structural safety against total or partial structural collapse. •Since this may lead to loss of life and major financial losses, ULS must have a very low probability of occurrence. 2 - Serviceability Limit States •Serviceability limits state (SLS) refer to the performance of structures under normal service loads, with use and occupancy of structures. • To satisfy serviceability limit state, deflections, cracking and vibration must not be excessive. •Violation of serviceability limit state may disrupt the use of structures but does not usually involve collapse 3- Special Limit States •Special limit states refer to structural damage or failure caused by abnormal or exceptional loadings: 1. Extreme earthquakes 2. Fire, explosions 3. Effects of corrosion and deterioration |
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3. Write briefly about Working Stress Method |
The basis of working stress method is that the permissible (allowable) stresses for concrete and steel are not exceeded any where in the structure when it is subjected to the worst combination of working loads. There is no load magnification but the strength is reduced to allowable limits (dividing by safety factors greater than units) The working (allowable) stress method can be expressed as: I <= Rall =R\FS or segma<=segmaall FS = Factor of safety, greater than unity R = Resistance R(all) = Allowable resistance L = Working load effects |
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4. write a short sentences about Ultimate Limit States |
• The object of design based on limit state method is to achiere an acceptable probability that a structure will not reach a limit state in its life time. Ultimate state limit is most used. This method of design takes into account the uncertainties in the material properties and loads through strength reduction factors and load magnifying factors. The ultimate limit state method can be expressed as: Vay R>= n sum i=1 alphai Li reduction factor. less than unity ф = Strength R = Resistance Li = Working load effects ai = Load factors, greater than unity • The summation sign demotes the combination of load effects from different load sources, such as dead load, live load, wind or earthquake loads, etc... • In the limit state concept of design of reinforced concrete structures, and ai are called partial safety factors and are determined using probabilistic methods. |
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5. Compare between ultimate limit state design (ULS) method an working stress method (WS) ? |
• With a well reduced allowable strength, the working stress (WS) method uses linear elastic analysis. •The WS uses a single factor of safety whereas the limit state method uses various partial safety factors which can be adapted to the various uncertainties associated with strength and loadings. • The working stress method does not account properly for the variability of strength and loads and is therefore unable to deliver an objective estimation of the level of safety |
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1) What are the different types of structural loading? |
Structural loading includes various types 1. Dead Loads 2. Live Loads 3. Wind Loads 4. Earthquake Loads 5. Hydrostatic and Soil Pressure 6. Other Natural Loads |
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2) List Environmental Loads |
A. Snow Loads (not in KSA) B. Earthquake C. Wind D. Soil Pressure E. Pounding of Rainwater F. Temperature Differentials |
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3) What does the wind & Seismic loads depend on? |
It depends on the location of the building. the building is built on a flat land or on mountain, and it also depends on building requirements in the country. It is usually for very high building. |
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4) Compare between Wind and Seismic Forces |
Back (Definition)
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Define column |
Columns are structural members in buildings carrying roof and floor loads to the foundations. Vertical (or near vertical) members supporting axial compression forces, bending moments and shear forces. Columns play a major role in structural safety. As compression members, failure of columns is more dangerous than in beams |
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Mention Types of Reinforcement concrete columns, and draw them |
RC columns either are tied (more than 90 %) or spiral (5 to 10 %). Special composite columns are sometimes used. |
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What is tied column? And Draw it |
In tied columns, which may be of any shape, independent ties are used. Tied columns have closed lateral ties spaced approximately uniform across the column |
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What is the role of ties? |
1. Hold and restrain main bars from buckling 2. Hold steel cage during construction 3. May confine concrete and provide ductility 4. Serve as shear reinforcement |
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Draw and mention the typical tied column sections |
Back (Definition) |
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-Define Reinforced concrete footings Foundations settlement -The design is based on? -The proper design of footings requires that |
Reinforced concrete footings are structural members used to support columns and walls and to transmit and distribute their loads to the soil. Foundations are the structural elements that are used to transfer the structural loads to the soil giving sufficient margin of safety against its failure, without excessive settlement and rotation. settlement The amount of settlement depends on many factors, such as the type of soil, the load intensity, the depth below ground level, and the type of footing. The design is based on the assumption that the footing is rigid, so that the variation of the soil pressure under the footing is linear. The proper design of footings requires that 1. The load capacity of the soil is not exceeded. 2. Excessive settlement, differential settlement, or rotations are avoided. 3. Adequate safety against sliding and/or overturning is maintained. |
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The types of footings and draw them |
TYPES OF FOOTINGS Different types of footings may be used to support building columns or walls. The most common types are as follows: 1. Wall footings are used to support structural walls that carry loads from other floors or to support nonstructural walls. 3. Combined footings Usually support two columns or three columns are located very near to each other. The shape of the footing in plan may be rectangular or trapezoidal, depending on column loads. 5. Continuous footings support a row of three or more columns. They have limited width and continue under all columns. 7. Pile foundation |
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The bearing capacity of soil |
The bearing capacity of soil The bearing capacity of soil is influenced by many factors for instance soil strength, foundation width and depth, soil weight and surcharge, and spacing between foundations. These factors are related to the loads exerted on the soil and considerably affect the bearing capacity. |
