The Superposition Theorem states that the total moment or deflection in a linear structure under multiple loads can be found by summing the effects of individual loads applied separately. This is valid as long as the structure behaves elastically --> follows Hooke's Law. Below is a complete list of the formulas we can use for any beam, but we will later discuss how we only need to memorize at least five formulas in total if we combine the concept of integration in formulas with point loads.
Image excerpted from Pytel, F., & Kiusalaas, J. (2012). Engineering Mechanics: Statics and Dynamics 4th ed. Cengage Learning. Used under fair use for educational and illustrative purposes.
Problem: Cantilever Beam with Uniform Load and Concentrated Load at the Free End
A 4-m long cantilever beam carries a concentrated load of 50kN at the free end and a uniformly distributed load of 20kN/m throughout the entire span. The beam is made of steel where E=200GPa and I=200x106mm4
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Problem: Cantilever Beam Resting on a Simply Supported Beam | Consistent Deformation with Superposition
Beam BD is fixed at D and is supported by girder AC at B with P=14kN applied at the free end.
L1=4m, L2=2m, L3=4m.
The Section Modulus of both members about the plane of bending is:
S=6.18x105mm3
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Problem: Application of Formulas for Fixed-Ended Beam
Refer to the load diagrams shown:
a. If MA = -10 kN-m, L = 6 m, calculate P in kN based on Figure A. a. 7.5
b. 10
c. 5
d. 12.5
b. If MA = -40 kN-m, L = 10 m, calculate w in kN/m based on Figure B.
a. 6.78
b. 8.76
c. 8.67 d. 7.68
c. If MA = -60 kN-m, MB = -90 kN-m, L = 10 m, calculate w in kN/m based on Figure C.
a. 15 b. 18
c. 21
d. 24
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Problem: Cantilever Beam with Uniform Load Resting on a Simply Supported Beam | Consistent Deformation
Refer to the figure shown. A cantilever beam rests on B of beam ABC. THe cantilever beam carries a uniform load W=24.6kN/m throughout its length. Prior to loading, the cantilever beam is only touching beam ABC at B. Both beams have identical cross-sectional properties. Given the following data:
L1=4m
L2=2m
E=30GPa
I=1333x106mm4
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Problem: Force to Apply at Mid-Length to Eliminate Deflection at Free-End
A 5-meter cantilever beam, 300mm x 400mm in cross-section carries a total uniformly distributed load of 5.20kN/m. E=25GPa. What force (in kN) should be applied at the mid-length of the beam to eliminate the deflection at the free end?
PSAD - Structural Theory / Slope and Deflection / Engr. Janclyde Espinosa (Clidez)
For the beam shown, assume EI is constant.
Determine the slope at the free end.
288/EI
144/EI
264/EI
132/EI
Determine the deflection at the free end.
1274.4/EI
1374.6/EI
1349.2/EI
1138.8/EI
Determine the slope at the midspan.
247.5/EI
240.6/EI
270.9/EI
250.5/EI
Determine the deflection at the midspan.
441.45/EI
508.95/EI
430/EI
540/EI
Solution pending in psadquestions/q309.json.
Question Bank: q310
PSAD - Structural Theory / Slope and Deflection / Engr. Janclyde Espinosa (Clidez)
For the beam shown, assume EI is constant.
Determine the slope at the free end.
1800/EI
1600/EI
1700/EI
1500/EI
Determine the deflection at the free end.
7200/EI
3600/EI
6800/EI
3400/EI
Determine the slope at the midspan.
1350/EI
1250/EI
1400/EI
1375/EI
Determine the deflection at the midspan.
2250/EI
2500/EI
2480/EI
2360/EI
Solution pending in psadquestions/q310.json.
Question Bank: q311
PSAD - Structural Theory / Slope and Deflection / Engr. Janclyde Espinosa (Clidez)
For the beam shown, assume EI is constant.
Determine the deflection at the midspan.
4258.8/EI
4285.8/EI
4288.5/EI
4528.8/EI
Solution pending in psadquestions/q311.json.
Question Bank: q312
PSAD - Structural Theory / Slope and Deflection / Engr. Janclyde Espinosa (Clidez)
For the beam shown, assume EI is constant.
Determine the deflection at 5.5m from the left support.
964.4625/EI
835.3125/EI
129.15/EI
1093.6125/EI
Determine the deflection at point C.
834.6/EI
735/EI
99.6/EI
934.2/EI
Determine the slope at D.
334.3/EI
297.5/EI
36.8/EI
371.1/EI
Determine the deflection at E.
802.32/EI
807.5/EI
714/EI
890.64/EI
Solution pending in psadquestions/q312.json.
Question Bank: q326
PSAD - Structural Theory / Slope and Deflection / Engr. Janclyde Espinosa (Clidez)
Using the three moment equation,
Calculate the deflection at B in mm.
0.176mm
0.167mm
0.156mm
0.165mm
Calculate the deflection at C in mm.
0.174mm
0.267mm
0.276mm
0.147mm
Solution pending in psadquestions/q326.json.
Question Bank: q332
PSAD - Structural Theory / Slope and Deflection / Engr. Janclyde Espinosa (Clidez)
Determine the deflection at the free end using Superposition Method.
Determine the deflection at C caused by the concentrated load alone. Remove the uniformly distributed load.
466.66/EI
333.33/EI
133.33/EI
366.66/EI
Determine the slope at B caused by the uniformly distributed load.
208.33/EI
133.33/EI
236.66/EI
254.58/EI
Determine the deflection at C
50/EI (downward)
50/EI (upward)
60/EI (upward)
60/EI (downward)
Solution pending in psadquestions/q332.json.
Question Bank: q544
PSAD - Structural Theory / Slope and Deflection / Engr. Deguma
A 6-meter-cantilever-beam (fixed at left) is loaded with 3 concentrated loads
P1, P2 and P3 applied at 2 m, 4 m, and 6 m from the fixed support,
respectively. If P1 = P2 = P3 = 30 kN and EI is constant, compute the
following:
The moment at 1m from the fixed support in kN-m.
270
180
210
360
The slope at the free end.
840/EI
480/EI
720/EI
540/EI
The deflection at the free end.
3600/E I
2400/EI
1800/EI
4800/EI
Solution pending in psadquestions/q544.json.
Question Bank: q565
PSAD - Structural Theory / Slope and Deflection / Engr. Deguma
The beam shown is acted on by moments M1=M2=100kN×m. If a=3m and EI is constant,