Dynamics of Rigid Bodies

1. The body has a mass of 100 kg and is pulled up a 75 percent inclined by a force P. The coefficient of friction f is 0.25 between contacting surfaces.
a) determine the constant value of P required to bring the body from the rest to a velocity of 6 m/s in 10s

b) what value of P will then suffice to maintain that velocity?

2. A nozzle on the end of a fire hose is 20 m from a vertical wall and makes an angles of 45 degrees with the horizontal. If the stream strikes the wall at a point 8 m above the nozzle, what us the velocity of water as it leaves the nozzle?

A city is evaluating the benefits to be achieved by changing the level of waste collection service. The change would result in (i) reduced service to the customer, (ii) an increase in the number of houses served daily by each crew, and (iii) a cost savings that would put off a 10% collection rate increase for 1 year. The existing rate for collection service (two containers per house) is $12.5/month. List the important variables for (i), (ii), (iii) separately that must be evaluated when the change is planned. Discuss the probability for successful implementation of the change.

A transportation engineer collected the data shown in the Table below. Develop a linear v-k model, and then establish v-q and q-k relationships. Draw v-k, v-q and q-k diagrams and depict all of the critical values (i.e., free-flow speed, jam density, maximum traffic flow, critical speed and density) in the three diagrams

USING ACI 318 Codes

Problem #3: Design the RC beam given the information below. Ensure that the reinforcement fits in the section, and that the section is tension controlled (i.e., phi = 0.90). Simply supported 20 ft beam.

w = 1 kip/ft (dead, does not include self-weight), 1.5 kip/ft (live); f'c = 5,000 psi; fy = 60 ksi; b = 14"; d = 28"; #3 Transverse Reinforcement.

Problem #4: Given the same information above, however Mu = 360 kip-ft; b and d are now unknown. Assume that 1.2D + 1.6L is the controlling load condition. Design the RC beam, and ensure that the reinforcement fits and that the section is tension controlled. Mu does not include the beam self-weight.

Please answer all 3 questions. Thank you!

1) What is the atomic structure and atom arrangement at metal grain boundaries?

2) What is the crystalline atomic structure of ceramics? (both type of bonds and type of structures)

3) Give several examples of common polymers that are thermoplastic and that are thermosetting.

B. A trapezoidal channel with a bottom width of 4 m and side slopes 4H: 1V carries a discharge of 30 m3 /s. The channel has bed slope= 0.1 % and manning roughness coefficient = 0.015. Determine the following:

i. the minimum specific energy

ii. the normal depth iii. the critical slope

iv. state of the flow in the channel

Prepare a duty list for a consultant assistant engineer of a civil engineering project (construction of a pedestrian bridge).

Q1. The short tied column is to be used to support the following factored load and moment: P= 1250 kN and M= 250 kN.m [10 marks]. fc=28 MPa fy=420 MPa

a) Determine required dimensions and reinforcing bars using appropriate ACI column approach [2 marks].

b) Determine maximum ACI design axial load strength for selected column [2 marks].

c) Determine balanced failure point on axial moment interaction diagram [2 marks].

d) Determine the tie size and spacing [2 marks].

e) Draw the typical tie arrangements dimensions [2 marks].

Chapter 9: Concrete Form Construction

Matching

Match terms to their definitions. Write the corresponding letters on the blanks. Not all terms will be used.

True/False

Write True or False before the statement.

1. Footings are the first part of a building to be installed.

2. Building forms for slabs, walks, and driveways are exactly the same as building continuous footing forms.

3. A vapor retarder provides a barrier to soil gases, such as radon.

4. All wall form systems use similar components to make them perform as expected.

5. Outside corners of concrete-forming systems are created by attaching panels to angle irons with wedges.

6. Walers are difficult to install on forming systems.

7. Riser form boards for stairs are beveled on the top edge.

8. Water should be added to concrete so that it flows into forms without working it.

9. A slump test shows the wetness or dryness of a concrete mix.

10. Curing agents placed on green concrete contain harmful chemicals.

Multiple Choice

Choose the best answer. Write the corresponding letter on the blank.

1. A combined slab foundation/footing is called a slab.

1. dual-duty
2. monumental
3. colossal
4. monolithic

2. When applying a vapor barrier of heavy plastic film under concrete, it should be lapped and sealed.

1. no more than 2 inches
2. between 1 and 3 inches
3. approximately 3 inches
4. at least 4 inches

3. is the only insulation recommended for ground contact and can be placed between concrete and the subsoil.

1. Extruded polystyrene
2. Extruded aluminum
3. Polyethylene
4. Polypropylene

4. The snap ties run through form boards and are wedged against additional form supports called .

1. form panels
2. anglers
3. walers
4. studs

5. Concrete-forming system panels are tied together with wedges.

1. formed plastic
2. wood or steel
3. concrete
4. polyethylene

6. The width of a step is called the .

1. rise
2. run
3. tread
4. edge

7. Which of the following statements about the placement of concrete is true?

1. Working it by hand will cause voids or honeycombs.
2. Vibrators should not be used with a stiff mixture.
3. Overvibrating decreases the lateral pressure on a form.
4. Vibration allows trapped air to escape the concrete.

8. Concrete must be protected from freezing for after being placed.

1. at least four days
2. a minimum of ten days
3. no less than two weeks if the air is humid
4. between ten days and two weeks depending on humidity

9. If moist-cured for seven days, concrete strength will be full strength.

1. up to about 60 percent of
2. more than 75 percent of
3. kept to less than 40 percent of
4. nearly or completely at

Terms

Read the descriptions of terms associated with concrete construction. Write the correct term on the corresponding blanks.

1. Provide a base on which to spread the load of a structure over a wider area of the soil

2. Provides a lock between the footing and the foundation wall

3. Hold wall forms together at the desired distance apart; support both sides against lateral pressure of concrete

4. Used to reinforce concrete floor slabs resting on the ground, driveways, and walks

5. Performed by inspectors on a job to determine the consistency of the concrete

Put in Order

Put in order the following steps for constructing footing forms. Write the corresponding numbers on the blanks.

A. Fasten the spreaders across the form at intervals necessary to hold the form the correct distance apart.

B. Stretch lines back on the batter boards in line with the outside edge of the footing.

C. Erect the inside forms in a manner similar to the outside forms.

D. Drive corner stakes to the correct elevation and stretch lines between the stakes, if desired.

Identify

Identify the following items use with concrete construction. Write the correct name on the line next to the item.

1.

Courtesy of Dayton/Richmond Concrete Accessories.

2.

Courtesy of Dayton/Richmond Concrete Accessories.

3.

© 2016 Cengage Learning^®

4.

© 2016 Cengage Learning^®

Procedures

Read the following procedures. Determine what procedure is being described and write the name of the procedure on the blank.

Procedure 1:

• Stretch lines again on the batter boards aligned with the outside of the foundation wall.
• Set panels directly on the concrete footing to the chalk line or on 2 × 4 or 2 × 6 lumber plates.
• Erect the outside wall forms first.
• Erect the panels for the inside of the wall.
• Install the walers. Let the snap ties come through them and wedge into place.
• Reinforce the corners with vertical 2 × 4s.
• If necessary, form the wall at intervals for the construction of pilasters, thickened portions of the wall.
• Brace the walls inside and outside as necessary to straighten them.
• The top surface of the concrete must be level and smooth to make attaching the wood frame easier.
• Set the anchor bolts into the fresh concrete.
• Install blockouts for larger openings.
• Install forms for girder pocket blockouts.

Procedure 2:

• Determine the rise and run of each step and lay them out on the inside of the existing walls or form.
• Secure cleats (short strips of wood) to the side wall form at each riser location.
• For earth-supported stairs, place fill that is free of organic matter and compacted in place to reduce settling.
• For suspended stairs, construct a support made of plywood, joists, shores, and stair horses.
• Install the rebars or reinforcing as specified by the prints.
• Install riser boards that are ripped to width to correspond to the height of each riser.
• Brace the risers from top to bottom at mid-span.

Calculations

Use the information provided to complete your calculations. Write answers on the lines provided within the exercises.

Estimating the Amount of Concrete for a Slab

Estimate the cubic yards of concrete for the slab shown below. The depth of the slab is 6 inches. Use the space provided for your calculations.

© 2016 Cengage Learning^®

Total cubic yards:

Estimating the Amount of Concrete for a Footer

Estimate the cubic yards of concrete for a footer. Use the space provided for your calculations.

© 2016 Cengage Learning^®

Total cubic yards:

Estimating Concrete Materials

Estimate the materials for a complete poured concrete foundation for a rectangular building 32' × 60'. Poured walls are 8 feet tall and 8 inches thick. Form boards are 12 feet long, and rebar is 20 feet long.

© 2016 Cengage Learning^®

File Upload

Maximum upload file size is 10MB

A direct shear test is conducted on a large specimen of dry sand (square cross section with following dimensions: 7.5 cm x 7.5 cm x 3.0 cm [height], Mass = 271.0 g) with a normal stress of 500 kPa. Failure occurred when the horizontal force was 1.96 kN. For the same sand, tests were also conducted to determine the specific gravity and the maximum and minimum void ratios. These tests yielded the following results: Gs= 2.65, emax=0.80, emin = 0.45. a) Calculate the relative density of the sand specimen b) Determine the friction angle of the soil. c) A triaxial specimen (H= 8.0 cm, D = 3.8 cm, Dr~45%) is prepared using the same sand. The test is performed on a saturated specimen with a chamber pressure of 500 kPa and an initial value of the pore pressure u of 100 kPa. Assuming that the results of the direct shear test can be used to predict those of the triaxial test, at what value of the total axial stress does the triaxial specimen fail?

2. The La Salle Bus Company has decided to purchase a new bus for $95,000 with a trade-in of their old bus. The old bus has a BV of $10,000 at the time of the trade-in. The new bus will be kept for 10 years before being sold. Its estimated SV at that time is expected to be $15,000.

a. Determine which asset class of the bus.
b. Determine annual Straight-Line Depreciation charge.

Shouldgovernment (state or federal) subsidies be provided to rural communities for the recycling of paper, plastics, glass, and tin cans? What are the advantages and disadvantages of such subsidies? Could the money that would be spent on such subsidies be spent more effectively? How?

Consider a lake with 65 × 106 m2 of surface area for which the only source of phosphorous is the effluent from a wastewater treatment plant. The lake is receiving a flow rate of 1 m3/s from the wastewater treatment plant, which has a phosphorous concentration of 20 mg/L. The lake is also fed by a stream having 20 m3/s of flow with no phosphorous in it. If the phosphorous settling rate is estimated to be 10 m/yr. (a) Write down the phosphorous mass balance equation for the lake and draw a control volume diagram for the lake showing influent streams, effluent streams, point-discharge source. (b) Estimate the average phosphorous concentration in the lake at steady-state. (c) Bonus Q: What level of phosphorous removal at the treatment plant would be required to keep the average lake concentration below 0.02 mg/L?