Week 4 Challenge

1. Given Data:

Length of Abutment Wall = 5m

Thickness of Abutment Wall = 0.5m (Assumed)

Height of Abutment Wall = 9m (Assumed)

Height of Backfill = 7m

Height of Backfill at G.L. = 3m

Depth of Foundation = 1m

Unit weight of soil = 18kN/m3

Unit weigth of saturated soil = 19kN/m3

Unit weight of water = 10kN/m3

Water Table Level at Ground Level = 3m

Finding the earth pressure acting on the abutṁent wall.

2. Load Calculations:

First calculating the active earth pressure since water table is at ground level so there will be a submerged condition for that we use this formula,

Active Earth Pressure

K1 = Ka x (γsat - γw) x h

= 0.35 x (19-10) x 3

= 9.45kN/m2

Earth Pressure at Rest

K2 = Ko x (19-10) x h

= 0.5 x 9 x 7

= 31.5kN/m2

Now calculating the soil load to the foundation

P1 = γ X h

= 18 x 3

= 54kN/m2

P2 = γ x h

= 18 x 7

= 126 kN/m2

3. Staad Pro Modelling and Analysis:

First I created the model in staad pro as per the given data. Where I modeled my abutment wall and raft foundation by using plate member where I mesh my abutment and raft plate by 0.5m.

2. Then I assign the property where I give 1m thickness to raft foundation. And I assign 0.5m thickness to the Abutment wall.

3. After that I created the support to foundation by giving subgrade modulus 12500kN/m2 and assigned it to the raft.

4. After that I define the load definition. Where I defined three types of load to the structure.

1. Active EP: In active EP, since the loaing of earth pressure is linearly varying which is maximun at the bottom and minimum at the top. I defined the Hydrostatic loading. Where Fisrt I select the active EP sides of plate at G.L. which is at 3m. After that I gave the property of W1 = 0, W2 = 9.45kn/m2 Interpolating along Y global axis and GX direction of pressure.

2. EP at Rest: In EP at rest, since the loaing of earth pressure is linearly varying which is maximun at the bottom and minimum at the top. I defined the Hydrostatic loading. Where Fisrt I select the EP at rest sides of plate at backfill level which is at 7m. After that I gave the property of W1 = 0, W2 = -31.5kn/m2 Interpolating along Y global axis and GX direction of pressure.

3. Soil load to the Foundation:

Soil load to the Foundation: In this type of loading I divided my load into four types.

(a). Partial Plate load on active EP side: Since I Mesh my plates at 0.5m distance where my abutment wall thickness is 0.5m so on each side there will be of 0.25m of abutment wall resting on the raft and we know that the soil load will act on the raft plate where soil is acting since abutment wall is acting on the raft at 0.25m on each side so there will be no soil load will act so we have to gave load partially on that specific plates, so I select that side of plates and goes to load definition on plate loading where I goes to partial plate load and gave the property as W1 = -54kN/m2, X1=0, Y1 = -0.25, X2= -0.25, Y2= 0.25.

(b): Partial Plate load on EP at Rest side: Same as Partial Plate load on active EP side where I goes to partial plate load and gave the property as W1 = -126kN/m2, X1=0, Y1 = -0.25, X2= 0.25, Y2= 0.25.

(c): Pressure on Full Plate on active EP side: On active EP side where completly soil load acting on the raft plate I gave the load definition of Pressure on Full Plate where I gave the property of W1 = -54kN/m2 on global Y direction.

(d): Pressure on Full Plate on EP at Rest side: On EP at rest side where completly soil load acting on the raft plate I gave the load definition of Pressure on Full Plate where I gave the property of W1 = -126kN/m2 on global Y direction.

After that I gave the run analysis command and goes to the Post Processing mode. Where I first select the abutment wall and goes to the plate results for that I first choose load case of Active EP and stress type MX i.e. bending moment in X direction. Where I got Maximum Bending moment of 11.292 kN-m/m

After that I again select the abutment wall and goes to the plate results for that I again choose load case of Active EP and stress type MY i.e. bending moment in Y direction. Where I got Maximum Bending moment of 1.91 kN-m/m

After that I again select the abutment wall and goes to the plate results for that I again choose load case of Active EP and stress type SQX i.e. maximum shear force in X direction. Where I got maximum shear force of 25.079 kN-m2

After that I again select the abutment wall and goes to the plate results for that I again choose load case of Active EP and stress type SQY i.e. maximum shear force in Y direction. Where I got maximum shear force of 4.773 kN-m2

After that I again select the abutment wall and goes to the plate results for that I again choose load case of EP AT REST and stress type MX i.e. bending moment in X direction. Where I got Maximum Bending moment of -237.69 kN-m/m

After that I again select the abutment wall and goes to the plate results for that I again choose load case of EP AT REST and stress type MY i.e. bending moment in Y direction. Where I got Maximum Bending moment of -40.032 kN-m/m

After that I again select the abutment wall and goes to the plate results for that I again choose load case of EP AT REST and stress type SQX i.e. maximum shear force in X direction. Where I got maximum shear force of -239.58 kN-m2

After that I again select the abutment wall and goes to the plate results for that I again choose load case of EP AT REST and stress type SQY i.e. maximum shear force in Y direction. Where I got maximum shear force of 105.839 kN-m2

After that I select the Raft Foundation and goes to the plate results for that I choose all three types load and stress type MX i.e. bending moment in X direction. Where I got Maximum Bending moment of 86.53 kN-m/m

After that I select the Raft Foundation and goes to the plate results for that I choose all three types load and stress type MY i.e. bending moment in Y direction. Where I got Maximum Bending moment of 14.71 kN-m/m

After that I select the Raft Foundation and goes to the plate results for that I choose all three types load and stress type SQX i.e. shear force in X direction. Where I got Maximum shear force of 186.34 kN-m2

After that I select the Raft Foundation and goes to the plate results for that I choose all three types load and stress type SQY i.e. shear force in Y direction. Where I got Maximum shear force of 2.27 kN-m2