Week 3 Challenge

1. 1. State the primary load cases to be considered for design.

Ans- Primary load cases to be considered for design are

• Self-weight
• Nodal load
• Member load
• Physical member load
• Area load’
• Floor load
• Plate load
• Solid load
• Temperature load
• Seismic load
• Time history
• Wind load
• Snow load
• Response spectrum
• Repeat load
• frequency

2. What is One – Way slab?

Ans- If the longer span to shorter span ratio is equal to or more than two, the slab is called one way slab.

3. What is the value of unit weight of structural steel and soil?

Ans-

• Unit weight of structural steel= 78.5 KN/m³
• Unit weight of soil = ( 10-25.5) KN/m³

4. Name few sections that can be defined using Properties tab in STAAD Pro.

Ans-

• Circle
• Rectangle
• Tee
• Trapezoidal
• General
• Tapered I
• Tapered tube
• Angle, double angle, beam, column and channel

5. Define Primary Beams.

Ans- Primary beam

Beams that are supported directly over the column that is call primary beam.

2.1. State the factors and parameters that influence the design pressure intensity of a high-rise building.

Ans-

Factor and parameters that influence the design pressure intensity of a high rise building

• Different type of load i.e. dead load, live load, wind load and seismic loads.
• Size of the building and size of the members in the building.
• Different type of the materials
• Foundation

2.Mention the load transfer process of a Reinforced Concrete Building.

3.1. Differentiate One-Way and Two way slabs. Elaborate each slab type.

Ans-

One way slabs

• Longer span to shorter span ratio is equal to or greater than 2.
• Bending direction in one direction only.
• In one way slab, primary reinforcement is required in only one direction.
• Beams are used to support a one way slab on just two sides.
• In a one-way slab, the structure of load distribution is in one direction for shorter spans.

Two way slabs.

• Longer span to shorter span ratio is less than 2.
• Bending direction in both the direction.
• In two way slab, main reinforcement is required in both the direction.
• Beams are used to supporting the Two-Way Slab on all four sides.
• Four sides make up the two-way slab’s load distribution design.

2. Explain the concept of secondary beams with proper sketch.

Ans- Secondary beams-

• The beam which is supported over the primary beam that is called secondary beam.
• Support on the primary beam would be hinged supported.
• Secondary beam transfer the loads to the primary beam.

3. Mention the Primary load cases.

a-State the Indian Standards for each load case

ans-

• dead load- IS 875-part 1
• Live load – IS 875-part 2
• Wind load- IS 875-part 3
• Earthquake load- IS 1893

b-Detail the parameters of each load case

Ans-

For dead load

• Self-weight load (unit weight of the material)
• Super imposed load ( floor finishing load, wall load etc)

For live load

• Type of building
• Type of room
• Machinery

For wind load

• Design wind load
• Wind velocity
• Risk coefficient
• Terrain roughness
• Topography factor
• Importance for cyclonic region

For seismic load

• Time factor
• Location
• Intensity of the earthquake
• Design spectral acceleration
• Design lateral force
• ductility

c-Brief each load case

• Dead load-Dead loads are structural loads of a constant magnitude over time. They include the self-weight of structural members, such as walls, plasters, ceilings, floors, beams, columns, and roofs.
• Live load- it refer to the transient forces that move through a building or act on any of its structural elements. They include the possible or expected weight of people, furniture, appliances, cars and other vehicles, and equipment.
• Wind load- Wind load refers to the pressure caused by the wind that is delivered to a structure. This weight is dispersed over the structure's total area.
• Seismic load- seismic loading depends, primarily on seismic hazard, geotechnical parameters of the site, and structure's natural frequency etc. There are horizontal and vertical components of earthquake ground motions.

4. Detail the steps involved in assigning Properties and Support to a model using STAAD Pro sequentially.

Ans- Input properties

• After creating the geometry, section properties is created.
• The material properties is created and then the section and material is to be assigned to the member by selecting the required member.

Assigning of the support

• After assigning the members properties, then the support condition is to be created as per the requirement, then by selecting the nodes the requirement support condition is to be assigned.

5. Brief the steps to be followed to create and assign secondary beams in STAAD Pro.

Ans-

Step-1 – firstly create the model and assign the material and section properties to the model.

Step-2- create a beam such that both the ends of beam should lay on the primary beam.

Step-3- As the secondary beam should be simply supported. So the end should be behave like hinged support.

Step-4- create internal hinges at the ends of the secondary beam. Go to specification on the analytical analysis and specify the beam.

Step-5 create the two member specification for start and end and release the Fx and Mz.

Step-6- After creation of the member specification, assign both the member specification to the secondary beams.

Practical

1. Calculate the wind pressure for the given building
2. Building Dimension : 20m x 30m x 20m height RCC
3. Building usage : Hospital block in city centre
4. Location : Darjeeling

Ans- Given data-

1. Building Dimension: 20m x 30m x 20m height RCC
2. Building usage: Hospital block in city centre
3. Location: Darjeeling

Wind pressure of the given building has been calculated on excel which has been uploaded.

2. Calculate the Dead load and Live load for the above building with reference to IS standards ( assume suitable sections )

Ans-

Given data

1. Building Dimension: 20m x 30m x 20m height RCC
2. Building usage: Hospital block in city centre
3. Location: Darjeeling

Assuming data

Thick of the slab (PCC)= 150mm

Thickness of tile flooring= 50mm

Thickness of the brick wall=230mm

Density of the pcc= 24 KN/m³

Density of the tile= 17 KN/m³

Density of the brick wall= 18 KN/m³

Height of the wall= 3.5m

Dead load calculation,

a- Self weight- self weight of the building can be calculated directly by Staad pro.

b- Super imposed load-

• Floor finishing load= load of slab+ load of tile finishing

= 24×0.150+ 17×0.05

=4.45 KN/m²

• Brick wall load= 18× 0.23×3.5

=14.49 KN/m

Live load calculation

For the hospital building

• Office rooms and OPD rooms= 2.5 KN/m²
• Corridors, passages, lobbies and staircases including fire escapes as per the floor serviced but not less than 4 KN/m²
• Balconies= 4 KN/m²
• X-ray rooms, operating rooms, general storage areas -to be calculated but not less than 3 KN/m²
• Toilets and bathrooms= 2 KN/m²
• Bed rooms, wards, dormitories= 2 KN/m²
• Laboratories= 3 KN/m²