Week 3 Challenge

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

A. The primary load cases to be considered for design are:

• Dead Load
• Live Load/Imposed Load
• Wind Load
• Earthquake Load

2. What is One – Way slab?

A. One way slab: The one-way slab is a slab, which is supported by parallel walls or beams, and whose length to breadth ratio is equal to or greater than two and it bends in only one direction (spanning direction) while it is transferring the loads to the two supporting walls or beams, because of its geometry.

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

A. Unit weight of Steel = 7850 Kg/m^3 Unit weight of soil = 1800 Kg/m^3

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

A. Sections that can be defined using properties tab in the STAAD.Pro are

• Circular section
• Rectangular section
• Trapezoidal section
• Tee section
• General section
• Tapered Tube

5. Define Primary Beams.

A. Primary Beam is a horizontal flexural (beam) structure member which directly connected to supporting compressive structure member that is column. Primary Beams are the beams located at the exterior of the structural elements. The beam cannot have much load on the exterior beam or the primary beam.

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

A. The factors and parameters that influence the design pressure intensity of a high-rise building are,

• K1 = Probability Factor (risk coefficient)
• K2 = Terrain , height and structure size
• K3 = Topography factor

Design wind pressure,

• The wind pressure at any height above mean ground level shall be obtained by the following relation ship between wind pressure and wind velocity.
• Pz = 0.6 Vz^2

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

A. The load transfer process of a Reinforced Concrete Building is

• Slab
• Secondary Beam
• Primary Beam
• Columns
• Foundation
• Soil beneath

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

A.

Sl.No	One-way slab	Two-way slab
1.	The Ratio of the Longer span to the shorter span is greater than 2.	The ratio of the longer span to the shorter span is less than or equal to 2.
2.	Where Lx/Ly is greater than 2	Where Lx/Ly is less than or equal to 2.
3.	The bending moment occurs only in one direction i.e. the shorter direction in One Way Slab	Bending moment occurs in both directions i.e. shorter and longer

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

A. Secondary Beam: A horizontal beam connecting primary beams (simply supported or shear connected.)

Function: It will transfer the load to the primary beam and not directly connected to the columns.

3. Mention the Primary load cases.
a. State the Indian Standards for each load case

A. Dead load : IS 875 Part 1, Live load : IS 875 Part 2, Wind Load : IS 875 Part 3, Earthquake Load : IS 1893-2016 (Part-I)

b. Detail the parameters of each load case

A. Dead Load Depends on Unit weight. Volume of the section Rectangular/circular section. Live load Depends on Building type, Residential/ Comercial/Industrial. Area type Room/ Corrider/Toilet/Roof etc.,

c. Brief each load case

A.

Wind Load :The force exerted by the horizontal component of wind is to be considered in the design of building. Wind loads depends upon the velocity of wind, shape and size of the building. The method of calculating wind loads on structure is given in IS 875 (Part-3):1987.

Snow Load : The building which are located in the regions where snowfall is very common, are to be designed for snow loads. The code IS 875 (Part-4):1987 deals with snow loads on roofs of the building.

Earthquake Load : Earthquake loads depend upon the place where the building is located. As per IS 1893-2016 (Part-I) (General Provisions for Buildings), India is divided into four seismic zones. The code gives recommendations for earthquake resistant design of structures.

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

A. The steps involved in assigning Properties and Support to a model using STAAD Pro sequentially are:

1. Double click on the STAAD.Pro software to open the software.

2. Next step we need to click on New and give the details as per the file, like name of file as XYZ and engineer as Sai vihari. And click on create to create a file.

3. Now we need to a create a beam of x. A beam of x is to be drawn for that we need to specify in the nodes so that a beam is created.

4. Materials which is concrete and properties of beam are assigned to the beam created.

5. Next step is to assign supports to the beam as per the requirement. Now support are added as per the scheduled.

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

A. The steps to be followed to create and assign secondary beams in STAAD Pro:

1. First create a simple model by using node in staad Pro
2. Click on Create beam option and create a beam in the direction of x and z axis

3. Click on the primary beam in the section

4. Right click and add new node in the beam section a node will be added

5. Again click on the create beam

Practical

Aim: To calculate the wind pressure for the given building
a. Building Dimension : 20m x 30m x 20m height RCC
b. Building usage : Hospital block in city centre
c. Location : Darjeeling

Procedure:

Wind pressure, according to IS 875 Part-3,

Pz = 0.6Vz^2

Where Vz = Vb*k1*k2*k3

Vb = Wind speed at certain location = 50

k1 = Risk coefficient = 1.0

k2 = terrain height and structure factor = 0.8

	Height	k2	Vz	Pz	Pz in kN
	3.5	0.80	40	960.00	0.96
	7.0	0.80	40	960.00	0.96
	10.5	0.80	40	960.00	0.96
	14.0	0.80	40	960.00	0.96
	17.5	0.80	40	960.00	0.96
	21.0	0.82	41	1001.23	1.00
	24.5	0.88	44	1152.38	1.15
	26.0	0.90	45	1220.41	1.22

	Interpolation For k2
	Height	k2
	20	0.8
	26	0.902
	30	0.97

k3 = Topography factor = 1

Vz = Vb*k1*k2*k3

= 50 * 1.0 * 0.8 * 1

Vz = 40 m/s

Pz = 0.6 * 40^2 = 960 = 0.96N/m^2

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

A. The dead load of the section considering the section length 5m and width 0.23m

• Dead load of the section = Unit weight * Volume of the section
• Unit weight = 25KN/m
• Volume of the section = 0.5*0.23*1 = 0.115m^3
• Dead load = 25 *0.115 = 2.875 KN/m

Live Load = Considering the general building,

Bath rooms and toilets in all types of the building, kitchens in,

1. Dweeling houses 2 , 1.8
2. Hostel, hotel, hospital 3 , 4.5