CVEEN3510_Review3-Solutions

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University of Utah *

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3210

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Civil Engineering

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Apr 3, 2024

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Page 1 of 10 CVEEN 3510-001 Civil Engineering Materials Spring 2023 Review for Exam 3 21 April 2023 Name (PRINT) _______________________ Student ID _______________________ Total points: 60 points Time: 120 minutes (1:00 to 3:00 PM) Instructions: 1. This exam is closed book. 2. You are allowed to bring ONE A4 sheet (8.5' by 11') of paper with any handwritten information. Everything on the paper must be handwritten. No computer-generated content will be allowed. In your sheet of paper, you can include concepts, examples, definitions, and ALL equations. You can use both sides of the paper. 3. NCEES Approved Calculator, official drawing aids (French curves, templates, etc.) are approved. 4. No cell phone, smart watch, or communication enabled are allowed. 5. You have 120 minutes to complete. The entire exam has a value of 60 points with an option for 12 bonus points. 6. Attempt all questions from PART A (18 x 2 = 36 points) and any four questions from PART B (4 x 6 = 24 points). 7. Bonus Points: There are 6 bonus questions (6 x 2 = 12 points). It is an optional section. 8. Review and sign the statement of academic integrity below. Statement of Academic Integrity As a University of Utah student and an aspiring professional engineer, your honesty and integrity are expected. By signing below, you affirm that the work provided is solely yours, that you have not used another’s assistance or work (with or without their consent), and that you will/have not discussed the contents of this exam with ANYONE prior to 3:00 PM. Printed Name -------------------------- Signature---------------------------------

Page 2 of 10 ------------------------------------------------------------------------------------------------------------- PART A (Answer all questions) Each question carries two points Total points for PART A is 36 1. C oordination number is the number of “nearest neighbors” for a crystal structure. The coordination number is for BCC, FCC and HCP structures, respectively are: a) 4,8,16 b) 2,4,8 c) 8,12,16 d) 8,12,12 2. A tensile load of 190 kN is applied to a round metal bar with a diameter of 16 mm and a gauge length of 50 mm. Under this load, the bar elastically deforms so that the gauge length increases to 50.1349 mm and the diameter decreases to 15.99 mm. The Poisson’s ratio for this metal is: a) 0.23 b) -0.23 c) 0.33 d) 0.27 Poisson’s ratio = -(change in diameter/original diameter)/ (change in length/original length) = - {(15.99-16)/16}/{(50.1349-50)/50} = 0.23 3. A given viscoelastic material is modeled using a Maxwell Model with the following constants spring constant, K = 20 N/mm; shock absorber constant, beta = 1500 Ns/mm. If a creep load with a magnitude of 100 N is applied for 60 seconds, the deformation, in mm, will be: a) 9 mm b) 4 mm c) 5 mm d) 8 mm Maxwell model , Total deformation = F/K + Ft/beta = 100/20 + (100 × 60)/1500 = 9 mm 4. Measurements should be reported to the nearest 1000, 100, 10, 1, 0.1, 0.01, 0.001 units, etc., depending on their variability and intended use. Using your best judgment, how should the following measurements be reported? • Compressive strength of Portland cement concrete (psi) • Moisture content in a concrete masonry unit (percent) a) 10 psi, 0.001% b) 100 psi, 0.01% c) 10 psi, 0.1% d) 100 psi, 0.1% Both c and d are acceptable 5. Which LEED credit area can be awarded the greatest number of points? a. Water Efficiency b) Material and Resources c) Energy and Atmosphere d) Innovation 6. If a steel with a 33 ksi yield strength is used for a cold-formed shape, what would be the approximate yield strength of the deformed corner after cold-forming? a. 66 ksi b) 49 ksi c) 99 ksi d) 28 ksi Cold-forming doubles the yield strength

Page 3 of 10 7. An aluminum specimen originally 300 mm long is pulled in tension with a stress of 275 MPa. If the deformation is entirely elastic, what will be the resultant elongation? The aluminum modulus of elasticity is 75 GPa. a. 1.1 mm b) 0.1 mm c) 2.1 mm d) 0.2 mm Stress = E (strain) = E (change in length / original length) 275 = 75 × 10 3 (change in length/300) Elongation or change in length = 1.1 mm 8. Glass used in a high-rise building is produced with an average tensile strength of 14 ksi with a standard deviation of 2 ksi. If 50 samples are tested, what is the lowest value that can be expected with 95% confidence? a. 10.08 ksi b) 11.02 ksi c) 12.06 ksi d) 10.8 ksi Z α/2 for 95% confidence level = -1.96 (lower bound) (x – mean)/standard deviation = -1.96 (x – 14)/2 = -1.96 x = 10.08 ksi 9. A sample of wet aggregate weighed 297.2 N. After drying in an oven, this sample weighed 281.5 N. The absorption of this aggregate is 2.5%. Calculate the percent of free water in the original wet sample. a. 3.08% b) 2.08% c) 1.8% d) 3.8% Moisture content = (297.2 – 281.5) /281.5 = 5.58% Absortion = 2.5% Free moisture = 5.58 -2.5 = 3.08%

Page 4 of 10 10. Select the most appropriate stress-strain for the following materials (in order) Glass, Steel, Aluminum, Concrete, Soft rubber a. A,B,C,D,E b) B,C,D,A,E c) C,D,A,B,E d) D,A,C,B,E 11. The mix design for an asphalt concrete mixture requires 2 to 6% minus No. 200. The three aggregates available and their corresponding minus 200 are Coarse = 0.5% , Intermediate = 1.5%, Fine aggregate = 11.5 %. Considering that approximately equal amounts of coarse and intermediate aggregate will be used in the mix, what is the percentage of fine aggregate that will give a resulting minus No. 200 in the mixture in the middle of the range, about 4%? a. 30% b) 25% c) 18% d) 42% Let x be the fraction of fine aggregate 4% = 0.5% {(1-x)/2} + 1.5% {(1-x)/2} + 11.5% {x} x ~ 30% 12. As a materials engineer in charge of designing concrete mix and facing the following problems, which admixture would you use if more time is expected to be needed for finishing concrete? a. Retarder b) Accelerator c) Air entrainer d) Superplasticizer 13. A continuou sly reinforced concrete pavement cross section contains a layer of No. 6 (0.75’’ diameter) reinforcing bars at 6-in. centers, such that the steel is just above mid-depth of a 10-in. thick slab. Cover over the top of the steel is therefore about 4 in. Choose the maximum size of coarse aggregate. a. 1.5’’ b) 3’’ c) 3.5’’ d) 2.7’’ < 1/5 x 10’’ < 3/4 x (6- 0.75)’’ < 3/4 x 4’’ Max size should not be more than 2’’, typically 1 - 1.5’’ used

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