Week 3 Challenge
AIM
- To calculate the wind pressure for the given building
- To calculate Dead load and Live load
- To study elements in Staad pro
INTRODUCTION
STAAD.Pro is one of the popular software that is used for analyzing & designing structures like – buildings, towers, bridges, industrial, transportation and utility structures
Here we create supply supported beam with loading and analyze the beam using STAAD PRO
PROCEDURE
1.1. State the primary load cases to be considered for design.
Dead load
Live load/Imposed load
Wind load
Earthquake load
1.2. What is One – Way slab?
If the ratio of Longer direction(Lx) to Shorter direction(Ly) is greater than 2 , then we classify it as a One way slab Lx/Ly> 2
In practical, One way slab is supported by only two parallel beams or walls
In one way slab, the load is carried in one direction perpendicular to the supporting beam
1.3. What is the value of unit weight of structural steel and soil?
Structural steel is 7840 kg/m^3
Soil is 18kN/m^3
1.4. Name a few sections that can be defined using the Properties tab in STAAD Pro.
Circular section
Rectangular section
Tee section
Trapezoidal section
General section
Tapered I
Tapered tube
1.5. Define Primary Beams.
The beams that are connecting columns for transferring loads of a structure directly to the columns are known as primary beams
Primary Beams transfer the load from slab or secondary beams to the columns
2.1. State the factors and parameters that influence the design pressure intensity of a high-rise building.
The factors influence the design pressure intensity of a high-rise building are
K1- (probability factor)Risk coefficient.
K2- Terrain, height or structure size factor.
K3- Topography factor
Design wind speed is given by Vz = Vb x k1 x k2 x k3
Vz=Design wind speed at any height Z,
Where Vb is the basic wind speed
2.2. Mention the load transfer process of a Reinforced Concrete Building.
The loads from Slab-Secondary beam-Primary beam-Column-Foundation
3.1. Differentiate One-Way and Two way slabs. Elaborate each slab type.
|
One -Way Slab |
Two -Way Slab |
|
The one-way slab can be defined as the type of slab in which the ratio of the longer span to the shorter span is greater than two The bending moment occurs only in one direction L/B ratio is greater than 2 In a one-way slab, the crank is provided in two directions In a one-way slab, the main reinforcement is provided in a short span and distribution reinforcement is provided in a long span The one-way slab is supported by a beam on two opposite sides only |
The two-way slab can be defined as the type of slab in which the ratio of the longer span to the shorter span is less than two The bending moment occurs in two directions L/B ratio is less than 2 In a two-way slab, the crank is provided in four directions In a two-way slab, the main reinforcement is provided in both directions The two-way slab is supported by the beam on all four sides |
3.2. Explain the concept of secondary beams with proper sketch.
Secondary beams are the beams which runs between primary beams
Secondary beams will not have direct connections with columns
3.3. Mention the Primary load cases.
- State the Indian Standards for each load case
- Detail the parameters of each load case
- Brief each load case
Dead load - IS Code 875 part 1
Live Load - IS Code 875 part 2
Wind load - IS Code 875 part 3
Earthquake load-(IS 1893-2016)
Dead load
Dead loads are static forces that are relatively constant for an extended time.Dead load is generally considered as self weight of the structure,this loads are constant loads which are not going to change throughout the lifespan of structure
Live Load
Live load is a load that is not constant, but changes over time.It depends on kind of usage and occupancy and so it is variable.Live loads are the loads which are imparted by like different objects,furnitures,human lives,machinery and the live loads are not stationary it changes with time and position of the source
Wind load
Wind load is the load placed on the exterior of a structure by wind
Earthquake load
Earthquake load are the seismic loads which is in the category of Lateral loads which causes due the excitation of tectonic plates within the earth crust
4.Detail the steps involved in assigning Properties and Support to a model using STAAD Pro sequentially
After the geometry is completed
Click on Properties -
Then -Click on Define materials
Select the sections whichever you want (rectangular,circular etc )
Once the section is selected enter the section properties like width depth or dia etc
Select the materials like Concrete , Steel etc
Select the beam or column and Assign it to selected beams
After assigning properties to assign the support
Select the nodes using Node cursor
Go to Support
Click on create - and select the support
Then - Assign it to the selected nodes
5.Brief the steps to be followed to create and assign secondary beams in STAAD Pro
For creating secondary beams first we want to create primary beams and columns
After creating primary beams
select the beam in which you want to add a primary beam
After selecting the beam right click and chose the option for Insert node
Provide the location to add secondary beam
After providing the node points inserted,use add beam option and and draw the secondary 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
Wind pressure Pz= 0.6 Vz^2
where Vz = Vb x k1 x k2 x k3
Vb = Wind speed at the certain location = 50
k1= Risk coefficient = 1
k2= Terrain height and structure factor = 1.12
k3= Topography factor = 0.5
Vz= Vb x k1 x k2 x k3
= 50x1.0x1.12x0.5
=28 m/sec
Pz = 0.6 x(28)^2
= 0.47 N/m^2
2.Calculate the Dead load and Live load for the above building with reference to IS standards ( assume suitable sections )
Dead load for slab
Size of the slab=20X30(m)
Assume the depth of slab=150mm
Volume of slab=20X30X0.15=90 m^3
Normal density of Reinforced concrete=25 KN/m^3
Weight of slab=25(KN/m^3)X90(m^3)=2250 KN
Dead Load of Beam,
Assume the size of the section=500mmX600mm
Where, D=600mm. B=500mm.
Normal density of Reinforced concrete=25 KN/m^3
Volume of beam per unit length=0.5X0.6X1(m)=0.3m^3
Dead load calculation=Volume X density=0.3X 25=7.5
That is 7.5KN for 1 m of beam
Live load
Bedrooms,wards,Dressing rooms,dormitories,lounge=2KN /m^2
Kitchen ,Laboratory,Laundries =3KN /m^2
Dining room,cafeterias,restaurants =3KN /m^2
Toilets and bathrooms =2KN /m^2
X-ray rooms ,Operating rooms,General storage areas=3KN /m^2