Week 3 Challenge

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

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?

One Way Slab,

• The ratio of the longer span to the shorter span is greater than 2 is known as one way slab.
• Where Lx/Ly is greater than 2

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

The value of unit weight of structural steel and soil is given in IS 875 Part 1

• The unit weight of structural steel is 7840 Kg/M^3
• The unit weight of soil is 18KN/M^3

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

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

5. Define Primary Beams.

• 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
• Secondary beam laid on the primary beam.

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

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.

The load transfer process of a Reinforced Concrete Building is

• Slab
• Secondary Beam
• Primary Beam
• Columns
• Foundation

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

One way slab,

• The Ratio of the Longer span to the shorter span is greater than 2
• Where Lx/Ly is greater than 2
• the bending moment occurs only in one direction i.e. the shorter direction in One Way Slab

Two way slab,

• The ratio of the longer span to the shorter span is less than or equal to 2
• Where Lx/Ly is less than or equal to 2
• bending moment occurs in both directions i.e. shorter and longer

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

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.
• Tie Beam: A horizontal beam connecting two rafters in a roof or roof truss

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

• For Dead load : IS 875 Part 1
• Live load : IS 875 Part 2
• Wind Load : IS 875 Part 3
• Seismic Load : IS 13927 ,
  b. Detail the parameters of each load case
• 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 load case is a set of constraints and loads used to define a particular loading condition.
• You can use one or more load cases for the study. The optimization result is separately calculated for each load case
• A load case is a combination of different types of loads. During the analysis, loads or forces are applied to the structure, and the resulting deflections are measured.
• These loads and forces can be combined to create one or several load cases.

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

• Go to property section
• Click on Define material
• Select the section, Rectangular/Circular etc,
• Select the material type concrete, steel , aluminium
• For the rectangular section enter YD & ZD in column below
• click add and close
• Select the material type and assign to the selected view for the support
• click on the support
• click on create
• select type of support do we want to assign the section
• click on add close

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

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

• click on the primary beam in the section
• right click and add new node in the beam section a node will be added
• again click on the create beam

Practical
1. 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

ANS :

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 = 1.12

K3 = Topography factor = 0.5

Vz = Vb * K1*K2*K3

= 50 *1.0*1.12*0.5

= 28

pz = 0.6*28^2 = 470.4 = 0.47N/m^2

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

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. Dweling houses 2 , 1.8
2. Hostel, hotel, hospital 3 , 4.5