Week 3 Challenge

CHALLENGE-3

1.1 Primary load case to be considered for design-

Dead load, super imposed dead load, live load, earthquake load.

2. One way slab-

If the ratio of longer span and shorter span are greater than 2 the slab is considered as a one way slab. And the load of the slab are distributed through shorter span. For this type of slab requires thicker section than two way slab.

3.Value of unit weight of structural steel and soil-

Unit wt of structural steel is=78.5 Kn/m3

Unit wt of soil= 18 Kn/m3

4. Few section that can be defined using properties tab in staad pro-

Circle, rectangle, tee, trapezoidal etc.

5. Primary beam-

These are the beam which are rest directly over the column and transfer the loads from slab to column.

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

Dead load, live load, wind load, super imposed dead load, earthquake load etc.

2.Load transfer process of a reinforced concrete buildings-

For primary beam,

Slab- primary beam-column-foundation

For secoundary beam,

Slab-secondary beam-primary beam-column-foundation.

3.1.Differentiate between one way and two way slab-

ONE WAY SLAB	TWO WAY SLAB
Ly/Lx>2	Ly/Lx<=2
Load transfer through shorter span	Load transfer through both shorter and longer span.
Thicker section	Thinner section
Main reinforcement provide through shorter span	Main reinforcement are provided through both shorter and longer span.

2. Secondary beam-

These are the beam which are rest over primary beam and act like as a simply supported beam. It transfer the load through slab to primary beam to column.

3. Mentioned the primary load cases and state the Indian standard for each load cases-

Dead load-

self weight of structure. And the different unit weight of different materials and structures are consider from is 875-part 1.

Super imposed dead load-

Super imposed load are those which are considered as permanent load I,e floor finishes, service load etc.which cames under the floor slab or roof slab. And considere from is 875 part 1 (table-2)

Live load-

Based on the uses and occupancy we shall considered the live load from is 875 part 2 (table-1). These are not permanent load.

Wind load-

Wind load are consider for safety of the structure at the time of heavy wind blowing. Consider from is 875 part 3

Here we need to calculate design wind pressure by this formula, Pz=0.6 Vz^2

Where Vz=design wind speed=Vb*K1*K2*K3 m/s

Vb=basic wind speed which are specified in is 875 part 3 for different regions.

4. Steps involve to assign properties and support in staad pro-

For assigning the properties -go to properties- define- select the shape of the structure- give dimension- select the materials as concrete- add- then select the member which one properties will be assign- go to assign to selected beams- assign.

For assigning the support – go to support- create- select support type either roller or fixed – go to enforced but and release force and moments- add- for assigning select the support -use cursor to assign- and assign on position where needed.

5. Step to be followed to create and assign secondary beam in staad pro-

Set up the unit- create the node- connect the node through add beam -connect the nodes

Create a center point in primary beam and connect with another primary beam mid point-and create supports – assign it on structure- secondary beam act like as a simply supported beam- so at first we need to release the moments at the junction point of primary beam and secondary beam for zero end moment.

Practical-

1. wind pressure calculation of hospital building of 20 m height at Darjeeling-

Pz=0.6 Vz^2

Vz= Vb*K1*K2*K3

Where, Vb= wind speed=47 m/s( at Darjeeling)

K1=Risk coefficient=1.07

K2= Terrain factor=1.07 (for h=20 and assume category 2 terrain)

K3=Topography factor=1

Vz=47*1.07*1.07*1=53.81 m/s

Pz= 0.6* (53.81)^2=1737.3 m/s

2.Building length-20 m, width-30 m, height-20 m

Length wise bays=5, width wise bays=7, height wise bays=6

Dead load calculation-

Total beam length wise=56 nos of total length=56*20=1120 m

Total beam width wise=42 nos of total length=42*30=1260 m

Beam of length=400 mm and width of 600 mm considered

So total wt of beam= (1120+1260)*(0.600*0.400)*25=14280 KN

Total no of column=48 so length =48*20=960m

Column length=600*600 mm2

Total wt of column=960*(0.6*0.6)*25=8640 KN

Slab area=30 m* 20 m=600m2

Thickness=150 mm

Total 6 floor

So total wt of slab=6*(600*0.15*25) =2250 kn

Weight of stair=560 KN (assume)

So, total dead load=17954 KN

Live load calculation-

2. living rooms, bed rooms – 2.0 kn/m2 udl and concentrated load=1.8 kn
3. stair case=3.0 kn/m2 udl and 4.5 kn concentrated load.
4. roof accessible=1.5 kn/m2 udl and 3.75 kn concentrated load

d.inaccessible roof area=0.75 kn/m2 and 1.9 kn as concentrated load

7. lift machine room= 7.5 kn/m2 and concentrated load of 4.5 kn

f.toilets= 2.0 kn/m2 as udl.