Week 3 Challenge

Ans 1.1: The primary load cases that are to be considered for design are listed below:

• Dead Load (IS 875: Part I).
• Live Load (IS 875: Part II).
• Wind Load (IS 875: Part III).
• Snow Load (IS 875: Part IV).
• Seismic Load (IS 1893: 2016).

Ans 1.2: ONE-WAY SLAB:

• One-way slab is a plane surface of uniformly loaded which deforms into a cylindrical shape and hence the bending moment develops only in one direction. These type of slab is called one-way slab.
• One-way slab is a slab in which the ratio of the longer span to its shorter span is more than or equal to 2.
• One-way slab load distribution takes place along its shorter span.Hence bending also happens at the shorter span of the slab.

Ans 1.3:

Unit-weight of Structural Steel: 7850 Kg/m3

Unit-weight of Soil: 1800 Kg/m3

Ans 1.4: Few sections that can be defined using Properties tab in STAAD Pro are listed below:

1. Circular sections.
2. Rectangular sections.
3. I-Sections.
4. T-Sections.
5. Tapered-I sections.
6. Trapezoidal sections.
7. Custom Geometric Sections.

Ans 1.5: The primary beams are the beams that are directly connected with the column on both the ends. The function of the primary beams are to transfer the load of the slab directly to the column that they are resting on.

Ans 2.1: The factors and parameters that influence the design pressure intensity of a high-rise building are:

• Wind Speed
• Wind Pressure
• Wind pressure at different height

Ans 2.2: The load transfer process of a Reinforced Concrete Building are

Ans 3.1:

One-Way Slab	Two-Way Slab
One-way slab is supported by a beam on two opposite sides only.	Two-way slab is supported by beam on all the four sides.
In one-way slab load is carried in one direction perpendicular to the supported beam.	And in two-way slab load is carried in both directions.
If L/b ratio is greater than or equal to 2,then the slab is considered as the One-way slab.	If L/b ratio is less than or equal to 2,then the slab is considered as the Two-way slab.
The deflected shape of the one-way slab is cylindrical.	The deflected shape of the two-way slab is saucer-like shape
In one-way slab the quantity of steel is less	In two-way slab the quantity of steel is more as compared to the onw-way slab.
In one-way slab,bending takes place only in one direction that is along the shorter span.	In two-way slab,bending takes place along the both span.

Ans 3.2:

SECONDARY BEAM :-

The secondary beams are primarily connected to the primary beams mainly simply supported beams.

• The secondary beams are provided for the better distribution of slab loads along with the primary beams which rests on thed slabs.
• So mainly the secondary beams are the beams that are not directly connected to the columns. The secondary beams rest on the other beams that are directly rest on the column and those beams are known as the primary beams.
• So the secondary beams carries a certain amount of total load and help them to distribute the loads in the respective manner.
• In secondary beams,it is important to release the end moments at the supports,because of this all the secondary beams are provided with the pinned connection.

Ans 3.3a: Indian Standards for each load case are:

• Dead Load (IS 875:Part 1).
• Live Load (IS 875:Part 2).
• Wind Load (IS 875:Part 3).
• Snow Load (IS 875:Part 4).
• Earthquake Load (IS1893:2016).

Ans3.3b: Detail the parameters of each load case:

• Member Loads.
• Concentration Loads.
• Floor Loads.
• Plate Loads.

Ans 3.3c:

• Dead Load:
  • The dead load is defined as the continuous load in a structure i.e the load of machine etc and this load caused by the weight of the members that are pemanently attached to the particular structure.
  • The dead load of the structure comprised of the load of the column, load of the beam , loads of the floor slab, roofing,walls, the load of the windows or may be the load of the electrical fixture. All the loads which is permanent on the structure is called as the dead load of the structure.
• Live Load:
  • Live loads are the loads that are fully or partially vary from time to time on the structure.
  • Live loads are not constant loads throughout of the life span of a structure.
  • Live loads may vary time to time according to its usage or the occupancy.
  • Live load may vary depend on the type of the structure such as the residential building,commercial building,industrial building etc.
  • For residential building we use 3KN/sq.m Live Load.
  • Live loads on floors and the roofs consist of all loads which are temporarily placed on the structure. Some of the live loads (Unit Weight) are:

• Wind Load:
  • Wind Load is a force on a structure that is arising from the impact of the wind. Wind load is an important load case for the structure. We considered this type of load where the structure are situated or located in the hilly areas of the mountain areas where we can expect high speed of the winds that can affect the structure. In those areas we need to consider the wind loads.
  • Mainly we calculated the wind loads for the roofs of the structure.
• Earthquake Load:
  • Earthquake loads or seismic loads are also an important load case that needs to be considered while designing and analysing of the high-rise structure of the building.
  • Mainly we considered this type of loads where there are high chances of earthquakes or we can say we have to consider this load in the earthquake prone areas,where there is a high risk of earthquake.
  • And according to the codal provision,the dynamic seismic analysis can be carried out via any of the two methods and these two methods are spectrum analysis and the time history analysis.

Ans 4: Assigning Properties:

The steps that are involved in assigning the properties and support to a model using the STAAD Pro software have been discussed below:

• The first step in order to assigning the properties to a model in a model using STAAD Pro software,go to the Properties tab and then there will be a dialoige box and in that dialouge box there is an option called Define menu just click on that option.
• After clicking the define option there will be another dialouge box,in that dialouge box there will be a list of existing sectional properties,from that list choose the desired sectional property like Circular section,Rectangular section,Trapezoidal section etc.
• After choosing the section properties specify the dimensions in that dialouge box.
• And now there will be another option called Add just click on that option and then click OK.
• And now assign the property to the model or structure,and to assign the property select the section that we have just created from the created section,and click on the opion Assign to the selected view and then click on the assign option and then assign the property and done.

Assigning Support:

• In order to assign the Support to the model using the STAAD Pro software,go to the Section tab and then there will be another dialouge box and in that dialouge box there will be an option called Create New just click on that option.
• After clicking on that option there will be another dialouge box and in that dialouge box there will be another options like Fixed,Pinned,Fixed But etc.
• Click on the desired end conditions,then there will be an option called Add just click on that option.
• And now assign the Support to the model or structure,and to assign the support select the support that we have just created from the created section,and click on the opion Assign to the selected view and then click on the assign option and then assign the property and done.

Ans 5:

The steps that are involved in creating and assigning the secondary beams in STAAD Pro are discussed below:

• First create a simple model by using the node in STAAD .pro
• Click on the create beam option and create a beam in the direction of X and Z axis

• Right Click on primary beam in the section
• Right click and add Add node at the mid on the beam section a node will be added
• Click on the create beam to draw the beam along mid of the bay.

Practical:

Ans 1a: PROCEDURE:

Given:

Building dimensions:- 20m * 30m * 20m.

Buidling usage:- Hospital Block.

Location of the building:- Darjeeling.

• Calculate Design Wind Speed:

We know the formula to calculate the design wind speed,that is:

`\Vz = Vb k1 k2 k3 k4,`

Where

Vz = design wind speed at any height z in m/s,
k1 = probability factor (risk coefficient) (see 5.3.1),
k2 = terrain roughness and height factor (see 5.3.2),
k3 = topography factor (see 5.3.3), and
k4 = importance factor for the cyclonic region (see 5.3.4).

Vb= Basic wind speed

therefore

Vb= 47m/s.

k1= 1.07m/s

k2= 0.8

k3= 1

k4= 1

therefore

Vz= 47*1.07*0.8*1*1= 40.232 m/s.

Wind Pressure:

So we know that Wind Pressure =

Pz=0.6Vz*Vz.

therefore

Pz= 0.6*40.232*40.232= 971.17 N/m2= 0.97 KN/m2

Ans 2:

• Dead Load load of Slab:

Assume Thickness of Slab= 0.15

Unit weight of concrete= 25 KN/m3

Volume of Slab= 20*30*0.15= 90 m3.

therefore Dead Load of Slab= Volume of Slab*Unit weight of Concrete= 90*25=2250 KN/m3.

• Dead Load due to the beams:

Assume the beams of cross-section 350*450mm.

Dead load= 0.35*0.45*25= 3.9375= 4 KN

• Superimposed Loads due to the Partition walls:

Assuming 150mm thickness of brickwork.

Height of brickwork = Floor height - depth of the beam= 20-0.45= 19.55 m

Therefore,the dead load due to the brick masonary partition = 19.55*0.15*20= 58.65 KN.

• Live Load:

We can calculate the live load of a given structure by using the IS 875:Part 2,which states different live loads values for different rooms.

- As our building is the Hospital building,the all the proposed live load values for hospital building according to the IS 875:Part 3 has been listed below:

OCCUPANCY	LIVE LOAD
For ward rooms,dressing rooms,dormitories and lounges	2 KN/m2
Kitchen and Laboratory	3 KN/m2
Dining room and Cafeteria	3 KN/m2
Toilets and Bathrooms	2 KN/m2
X-ray rooms and Operating Rooms	3 KN/m2
Office and OPD Room	2.25 KN/m2
Corridor and Passages	4 KN/m2