Week 3 Challenge

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

• 1 K1 = Probability Factor (risk coefficient)
• 2 K2 = Terrain , height and structure size
• 3 K3 = Topography factor
• Design Wind Speed Vz varries and depends with these factors.
• Vz = Vb k1 k2 k3 m/s

• And Design wind pressure Pz,

  • 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
• Question 2.2 Mention the load transfer process of a Reinforced Concrete Building.
• Ans.
• Slab > Secondary Beam > Primary Beam > Columns > Foundation
• Question 3. 1. Differentiate One-Way and Two way slabs. Elaborate each slab type.
• Ans.
• 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
• 
• Question 3.2. Explain the concept of secondary beams with proper sketch.

• Ans.

• 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.
• 
• Question 3.3 Mention the Primary load cases.
• 
  a. State the Indian Standards for each load case
  b. Detail the parameters of each load case
  c. Brief each load case
• Ans.

• 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.
  • Question 3.4. Detail the steps involved in assigning Properties and Support to a model using STAAD Pro sequentially.
  • Ans.
  • Properties
  • 1 Go to Properties Tab
  • 2 Click on Define Material
  • 3 Choose Section and Material
  • 4 Click on Add and Close.
  • 5 Now Click on Assign to view and assign the Property
  • Support
  • 1 Go to Support Tab
  • 2 Click on Create
  • 3 Choose Support and click on Add and close
  • 4 Now Click on Use Cursor to Assign.

  • Question 3.5. Brief the steps to be followed to create and assign secondary beams in STAAD Pro

  • Ans.
  • 1 Add node at the desired location of the beam. New Add beam between Nodes.
    • 2 Now go to the Specification
    • 3 Select Beam
    • 4 Click on Release
    • 5 Click on Start and Tick on Fx and Mz and click Add.
    • 6 Now Click on End and Tick Fx and Mz and click Add
    • 7 Now Assign to the selected 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.

  • For Wind Pressure (Pz) = 0.6 Vz^2

    Where Vz = Vb x k1 x k2 x k3

    The Structure in category - 4 and Class B and designed for 100 years.

    From IS 875 Part 2

    Vb = 47 m/s
    K1 = 1.07 (Table 1, Clause 5.3.1)
    K2 = 0.76 (Table 2, Clause 5.3.2.2) (Categort- 4 ; Class - B)
    k3 = 1 (Clause 5.3.3.1)

    Hence; Vz = 47 x 1.07 x 0.76 x 1
    = 38.22 m/s

    And Pz = 0.6 (38.22)^2
    = 0.87 N/m^2

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

  • Self Weight of Concrete = 25 KN/m^2
    Self Weight of PCC = 22 KN/mm^2
    Self Weight of Brick Wall = 18 KN/m^2

    Dead load = (Weight of one Slab x 7) + Weight of Wall
    (25 x 0.150 x 30x20) + ( 18 x 3 x 30 x 0.115) + ( 18 x 3 x 20 x 0.115)
    =16060 KN

    Assume live load = 3KN/m^2
    Live Load = 20 x 30 x 3 = 1800 KN

    Total Live Load = 1800 x no of floors = 1800 x 6= 10800 KN