Week 3 Challenge

Week 3 Challenge

Jagadeep.M.M

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

Ans:

• Dead Load
• Live load / Imposed load
• Wind Load
• Snow load
• Earthquake load

2. What is One – Way slab?

Ans:

The one-way slab is a slab, which is supported by parallel walls or beams, and whose length to breadth ratio is equal to or greater than two and it bends in only one direction (spanning direction) while it is transferring the loads to the two supporting walls or beams, because of its geometry.

l/b ≥ 2

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

Ans:

• Unit weight of Structural steel is 78.5 KN/m^3
• Unit weight of soil is 18 KN/m^3

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

Ans:

• Circular section
• Rectangular section
• T section
• Trapezoidal section
• General section
• Tapered I section
• Tapered tube section

5. Define Primary Beams.

Ans:

The primary beams are directly connected with the column or shear wall on both the ends i.e., fixed in both ends. Primary beam works to transfer the slab load in the column.

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

Ans:
The design speed can be governed by the formula

Vz = Vb x k1 x k2 x k3 x k4

Where,

Vz = Basic wind speed, based on the location of the project in India

k1 = Risk coefficient factor

k2 = Terrain and height factor

k3 = Topography factor

k4 = Importance factor

The design wind pressure is given by the formula

Pz = 0.6 x Vz^2

2. Mention the load transfer process of a Reinforced Concrete Building.

Ans:

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

One Way slab	Two way slab
Longer spans to shorter spans ratio is more than or eqaul to 2.	There is no more than a ratio of 2 between longer & shorter spans.
In a one-way slab,primary reinforcement is required & given only in one direction.	IN two-way slab,main reinforcement is needed & given in both direction.
One direction is where bending happens.	Bending happens in both direction.
Beam are used to supporting a one-way slab on just two side.	Beam are used to supporting a two-way slab on all four side.
Additional depth is needed.	Less depth is nedded.
In one-way slab, the structure of load distribution is in one direction for shorter spans.	Four sides make up the two-way slab's load distribution design.

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

Ans:
The beams that are connecting primary beams for transferring loads of a structure to the primary beams are known as secondary beams. These beams are provided for supporting and reducing the deflection of beams and slabs.

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

• 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 – IS 1893 and IS 13920

b.Detail the parameters of each load case

Parameters of live load depends on the building type like Residential Building, Commercial Building, Industrial Building etc. The parameters may include room loads, Balcony load etc.

Parameters of Dead load Includes self weight, Volume of the structure etc

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/m^3
• Steel : 7850 Kg/m^3
• Sand : 1600 Kg/m^3
• Concrete : 2400 Kg/m^3
• RCC : 2500 Kg/m^3

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 the life span of a structure.

Live loads may vary time to time according to its usage or the occupancy.

Live load may vary depends on the type of the structure such as the residential building, commercial building, industrial building etc.

For residential building we use 3KN/m^2 Live Load

Live loads on floors and the roofs consists of all loads which are temporarily placed on the structure. Some of the live loads (Unit weight) are :

• All rooms and kitchen : 2 KN/m^2
• Bathrooms and toilets : 2 KN/m^2
• Balcony : 3 KN/m^3
• Staircase/Corridors : 3 KN/m^3

Wind Load :

Wind load is a force on a structure that is raising from the impact of the wind. Wind load is an important load case for the structure. We consider this type of load where the structure is 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 calculate the wind loads for the roof of the structure.

Earthquake Load :

Earthquake loads or seismic loads is 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

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

Ans:

• Click the node option & create the node
• Click the Add beam option & create the beam
• Define Property of Structure
• Goto Properties tab, click on Define
• Select require shape of structure and provide dimension
• Select material of structure & assign the properties
• Assigning Support
• Click the Support tab, click on Create
• Add supports as requirement
• Assign node in the support

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

Ans:

• Open the STAA.Pro software and create a new project
• Go to Geometry tab and create columns and beams by using nodes
• Click on add beam and draw the beam using beam cursor

• Select a primary beam and right click and select insert nodes you will get a dialogue box in that select Add mid point so that the nodes are created and secondary beam is drawn

• Go to properties tab and add rectangular section for beams and columns select the option add to
• selected beam and assign the property to the respective column and beam

• Go to specification tab in the select beam and select Fx and Mz so that secondary beam is acting as simply supported beam
• assign it 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:

Wind Pressure, Pz = 0.6 Vz^2

Where, Vz = Vb x k1 x k2 x k3

Vb = Wind speed at the Darjeeling location = 47

K1 = Risk coefficient = 1.07

K2 = Terrain height and structure factor = 0.8

K3 = Topography factor = 1.0

Vz = Vb x k1 x k2 x k3

Vz = 47 x 1.07 x 0.8 x 1.0

Vz = 40.232 m/s

Pz = 0.6 Vz^2

Pz = 0.6 x 40.232^2

Pz = 971.168 N

Wind pressure, Pz = 0.971 KN

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

Ans:

Assume the Dimensions of Structural Member-

Column size 0.4m x 0.4m

Beam size 0.23m x 0.4m

Slab thickness 0.150m

Floor height 3m

Dead Load/ Superimposed Dead Load on typical Floor

Interior Partition	1 KN/m^2
Floor Finish	2.20 KN/m^2
MEP Service	0.50 KN/m^2
Insulation And Water Proofing	0.2 KN/m^2
Parapet Wall	0.20 KN/m^2
Miscellaneous	1 KN/m^2

Total Dead Load On Typical Floor 5 KN/m^2

Live load :

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

OCCUPANCY	LIVE LOAD
For ward rooms, dressing rooms, dormitories and lounges	2.0 KN/m^2
Kitchen and Laboratory	3.0 KN/m^2
Dining room and Cafeteria	3.0 KN/m^2
Toilets and Bathrooms	2.0 KN/m^2
X-ray rooms and operating rooms	3.0 KN/m^2
Office and OPD room	2.5 KN/m^2
Corridor and Passages	4.0 KN/m^2