Week 3 Challenge

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).

2)

• 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.

3)

The value of unit weight of structural steel and soil are given below:

• Unit-weight of Structural Steel: 7850 Kg/cu.m.
• Unit-weight of Soil: 18 KN/cu.m.

4)

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

• Circular sections.
• Rectangular sections.
• I-Sections.
• T-Sections.
• Tapered-I sections.
• Trapezoidal sections.
• Custom Geometric Sections.

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.

2.1)

• The factors and parameters that influence the design pressure intensity of a high-rise building has been discussed below:

So the design speed can be governed by the below given formula:

Vz = Vb X k1 X k2 X k3 X k4.

where, Vz = Basic wind speed, that is based on the location of the project in India. 

k1 = Risk Co-efficient factor.

k2 = Terrain and height factor.

k3 = Topography factor.

k4 = Importance factor.

And then the, design wind pressure is given by the below formula:

Pz = 0.6 X Vz^2.

2)

• The load transfer procedure of a reinforced concrete building has been illustrated below in the form of the flowchart:

3.1)

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

2)

• 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 then 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.

3)

 a.State the Indian Standards for each load case:

• 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).

b.Detail the parameters of each load case:

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

c.Brief each load case:

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 permanently 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.

 Some of the Dead Load(Unit Weight) of the following materials:

• Cement : 1440 Kg/cu.m.
• Steel : 7850 Kg/cu.m.
• Sand : 1600 Kg/cu.m.
• Concrete : 2400 Kg/cu.m.
• RCC : 2500 Kg/cu.m.
• Soil : 1800 Kg/cu.m.
• Dead Load factor is 1.

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:

• All rooms and kitchen : 2 KN/sq.m.
• Bathrooms and Toilets : 2 KN/sq.m.
• Balcony : 3 KN/cu.m.
• Staircase/Corridors : 3 KN/cu.m.

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.

4)

•  Go to Properties Tab
•  Click on Define Material
•  Choose Section and Material 
•  Click on Add and Close.
•  Now Click on Assign to view and assign the Property
•  Go to Support Tab 
•  Click on Create 
•  Choose Support and click on Add and close
•  Now Click on Use Cursor to Assign.

5)

Add node at the desired location of the beam. New Add beam between Nodes.

• Now go to the Specification
• Select Beam
• Click on Release
• Click on Start and Tick on Fx and Mz and click Add.
• Now Click on End and Tick Fx and Mz and click Add   
• Now Assign to the selected Beam

4)PRACTICAL

1)

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

Height	K2	Vz	Pz	Pz in KN
3	0.76	38.22	876.47	0.87
6	0.76	38.22	876.47	0.87
9	0.76	38.22	876.47	0.87
12	0.76	38.22	876.47	0.87
15	0.76	38.22	876.47	0.87
18	0.76	38.22	876.47	0.87
20	0.76	38.22	876.47	0.87

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