This section is from the book "Cyclopedia Of Architecture, Carpentry, And Building", by James C. et al. Also available from Amazon: Cyclopedia Of Architecture, Carpentry And Building.
In the foregoing sections of this Cyclopedia numerous illustrative examples are worked out in detail in order to show the application of the various methods and principles. Accompanying these are samples for practice which will aid the reader in fixing the principles in mind.
In the following pages are given a large number of test questions and problems which afford a valuable means of testing the reader's knowledge of the subjects treated. They will be found excellent practice for those preparing for Civil Service Examinations. In some cases numerical answers are given as a further aid in this work.
1. Discuss the qualities of good building stone.
2. Describe the tests that you would apply to determine the qualities of a building stone.
5. What are the distinguishing characteristics of a good quality of brick?
6. Discuss the crushing strength of various kinds of brick.
7. Describe briefly the characteristics and method of manufacture of Sand-Lime brick.
8. Describe the essential features in the manufacture of concrete building blocks.
10. What is the essential characteristic of hydraulic lime?
11. What is the essential characteristic of slag cement, and for what kind of use is it especially suited?
13. How would you obtain testing samples from a carload of cement?
14. Why must kerosene or benzine be used instead of water in determining the specific gravity of cement?
15. While determining the specific gravity of cement by Le Chatelier's apparatus, it was observed that the introduction of 64 grams of cement increased the volume by 20.3 cubic centimeters. What was the specific gravity of the cement?
16. How many holes should there be in each square inch of a No. 100 sieve?
17. If a certain brand of cement requires 30 per cent of water to produce a paste of standard consistency, how much water should be used in a 1:3 mortar?
19. What general precautions should be taken in handling cement, to prevent deterioration?
20. How much tensile strength should be developed by briquettes of neat Natural cement, and also by those of neat Portland cement, in 7 days? Also in 28 days?
21. What are the desirable characteristics of sand for use in mortar?
24. What practical method would you adopt to mix a large amount of lime mortar in the proper proportions?
25. What is the effect of using lime in cement mortar?
26. Describe in your own words the principles underlying the mixing of concrete so as to obtain the best possible product.
27. Discuss the compressive strength of concrete, and its increase with the richness of the concrete.
28. What general principles must be followed to obtain the densest concrete when using sand and stone of definite sizes? How would you determine the required proportions?
29. Assume that the voids in the sand are measured to be approximately 40 per cent, and that the voids in the stone are approximately 45 per cent. Using barrels containing 3.8 cubic feet of cement, how much cement, sand, and stone will be required for 100 cubic yards of 1:3:6 concrete?
30. With cement at $1 .25 per barrel, sand at $1.00 per cubic yard, and broken stone at $1.40 per cubic yard, the cost including delivery on the site of the work, what will be the cost on the mixing board, per cubic yard of 1: 3: 6 concrete?
31. Under what conditions is it proper to use dry concrete?
32. What is the danger in the excessive ramming of very wet concrete?
33. Why is there any practical difficulty in bonding old and new concrete?
34. What is the effect of the freezing of concrete before it is set? How can concrete be safely placed in freezing weather?
35. Describe in detail how you would make concrete watertight by varying the proportions or by the use of cement grout.
36. Describe in detail the fundamental principle and the method of application of the Sylvester process.
37. Describe the method of waterproofing by the use of felt and asphalt, or by the use of asphalt alone.
38. What form of bitumen should be used for waterproofing purposes?
39. Discuss the effectiveness of concrete in preserving imbedded steel from corrosion.
40. Discuss the protection afforded to imbedded steel by the concrete, against fire.
41. What precautions should be taken to insure that hand-mixed concrete is properly mixed?
42. Discuss the relative strength of machine-mixed and hand-mixed concrete.
43. What tests should a high-carbon steel satisfy in order to be suitable for reinforcing concrete?
2. Give an outline of the method of dressing a stone which shall have a warped surface.
3. What is the purpose of bonding? Describe several ways in which it is accomplished.
5. What are the elements affecting the cost of stone masonry?
6. Describe the various kinds of bonds used in brick masonry.
7. What tools are used, and how are they employed in the operation of quarrying and dressing stone for ashlar masonry?
8. Describe the various methods used in measuring brickwork.
9. A brick pier is 20 feet high; it is required to carry a load of 400,000 pounds, and is to be laid in a 1 to 2 natural cement mortar. Assume that the pier is to be square, what should be its cross-sectional dimensions?
10. Assuming that two-men stone is to be used in making rubble concrete, what will be the proper proportiors of cement, sand, small broken stone, and rubble in such a concrete?
11. Describe the method of depositing concrete under water, using buckets.
12. What precautions must be taken when depositing concrete under water through a tube?
15. Discuss the bearing power of various kinds of soil.
16. Describe some of the methods of improving a compressible soil.
17. Describe some of the methods of preparing the bed for foundations on various kinds of soil.
18. What is the purpose of a footing?
19. The wall of a building has a thickness of 2 feet; the total load on the wall has been computed as 16,000 pounds per running foot of the wall; the soil is estimated to carry safely a load of 3,000 pounds per square foot. What should be the thickness and width of limestone footings to support this wall on such a soil?
20. Classify the various kinds of piles, describing their uses.
21. Under what conditions do timber piles rapidly decay?
22. What are the most necessary specifications for timber piles?
23. A wall having a weight of 15,000 pounds per running foot is to be built on two lines of piles placed 2 1/2 feet apart transversely. It is found that piles driven 20 feet into such a soil have an average penetration for the last five blows of 1.5 inches, when a 2,500-pound hammer is dropped 24 feet. What is the bearing power of such piles, and how far apart must they be placed longitudinally in order to carry that wall?
25. What are the relative advantages and disadvantages of concrete piles compared with wooden piles?
26. What is a grillage, and what is its purpose?
27. What combination of circumstances justifies the use of a cofferdam?
28. What is the essential disadvantage involved in the use of a crib as a foundation for a pier?
29. What general constructive principle is involved in the sinking of a hollow crib through a soft soil?
30. What is the fundamental principle involved in the use of pneumatic caissons, and what is the practical limitation as to the depth below the surface?
31. Describe the several ways in which a retaining wall may fail.
32. A retaining wall whose height is 24 feet is surcharged with earth at the natural slope; assuming 35° as the angle of repose for that material, and that the wall has a batter of 1 in 4 on the front face and a vertical rear face, what should be the dimensions of the wall?
33. What are abutment piers; and under what circumstances is their use desirable?
35. What precautions are necessary in the design of a stone box culvert, to prevent its being washed out?
36. What precaution should be taken to prevent a concrete sidewalk from being broken up by frost?
37. Describe the method of making and finishing the top surface of a concrete sidewalk.
1. Why is there but little if any structural value to a beam made of plain concrete?
2. State briefly the fundamental reasons for the economy of using concrete for compressive stresses, and steel for tensile stresses.
3. What is meant by the neutral axis of a beam?
4. What is the essential difference between the elasticity of concrete under compression and that of steel or wood?
5. Develop the formula (Equation 11) for the summation of the compressive forces in a concrete beam, employing your own language altogether, and elaborating in detail every step in the line of argument.
7. What is the practical effect of using more steel than the theory calls for? Does it make the structure any stronger?
8. Develop a series of equations (similar to Equation 23) on the basis of 1:2 1/2:5 concrete whose modulus of elasticity (Ec) is assumed at 2,650,000, and whose ultimate crushing strength (c') is assumed at 2,200 lbs.
9. Using a factor of 2 for dead load and a factor of 4 for live load, what is the maximum permissible live load which may be carried on a slab of 1: 2 1/2: 5 concrete with a total actual thickness of 6 inches and a span of 8 feet?
10. If a roof slab is to be made of 1:3:5 concrete and designed to carry a live load of 40 pounds per square foot on a span of 10 feet what should be the thickness of the slab, and the spacing of 3/8-inch square bars?
11. A beam having a span of 18 feet is required to carry a live load of 12,000 pounds uniformly distributed. Using 1:3:5 concrete and a factor of 4, what should be the dimensions of the beam whose depth is approximately twice its width?
12. What will be the intensity per square inch of the maximum vertical shear in the above beam?
13. What are the two general methods of providing for diagonal shear near the ends of the beam?
14. Make a drawing of the beam designed in Question 13, showing especially the reinforcement and the method of providing for the diagonal shear.
15. Discuss the advantage of using steel with a high elastic limit, and also the possible danger in such use.
16. Make a design for a slab of 1:3:5 concrete, reinforced in both directions, which is laid on I-beams spaced 10 feet apart in each direction.
17. What is the general structural principle which makes T-beams more economical and efficient than plain rectangular beams having the same volume of concrete?
18. What assumption is made regarding the distribution of compressive stress in a T-beam?
19. How is the width of the flange of a T-beam usually determined?
20. What principles govern the determination of the proper width of the rib of a T-beam?
21. Recompute the numerical problem, Example 1, Article 291, on the basis that the beams are to be spaced 6 feet apart?
23. What will be the bursting stress per inch of height at the bottom of a concrete tank having an inside diameter of 10 feet, designed to hold water with a depth of 40 feet? What size and spacing of bars will furnish such a reinforcement?
24. With a nominal wind pressure of 50 pounds per square foot, on a flat surface, what will be the intensity of the compression on the leeward side of the tank, allowing also for the weight of the concrete, and assuming a thickness of 12 inches?
25. On the basis of the approximate theory given in the text, what would be the required steel vertical reinforcement for the above described tank?
26. Design a retaining wall to hold up an embankment 30 feet high, making a cross-sectional drawing-and plan drawing similar to Fig. 113, assuming that the buttresses are to be 12 feet apart.
27. Compute the required detail dimensions and the reinforcement for the box culvert illustrated in Fig. 115, on the basis that the culvert is to be 10 feet wide, 12 feet high, supporting an embankment 15 feet deep, and also a railroad loading of 1,500 pounds per square foot.
28. A column is to be supported on a soil on which the safe load is estimated at G,000 pounds per square foot; the column carries a total load of 210,000 pounds; the column is 22 inches square; what should be the dimensions of the footing, and how should it be reinforced?
29. A pair of columns which are 12 feet apart, one of which carries a load of 210,000 pounds and the other a load of 150,000 pounds, are to be supported on the same soil as described above. What should be the dimensions of the compound footing which will carry both of these columns, and what should be its reinforcement? Make a detail drawing similar to Fig. 112, but showing all the dimensions.
30. Discuss the various ways in which steel may be used to reinforce a concrete column.
31. What should be the steel reinforcement of the column described in Question 28, on the basis that the compressive stress in the concrete shall not exceed 400 pounds per square inch?
32. In case the line of pressure on the column of Question 31 should be 3 inches away from the center of the column, what would be the maximum intensity of the pressure per square inch?
33. A column which is to carry a working load of 230,000 pounds is to be reinforced with spiral reinforcement, the spiral having a diameter of 18 inches. Assuming high-carbon steel, what should be the pitch and size of the spiral rod?
1. What are the difficulties in obtaining a satisfactory outer surface of concrete?
2. Describe two successful methods of obtaining a good outer surface.
3. When and how can acid be properly used in treating a concrete surface?
4. What pigments should (and should not) be used for coloring concrete?
5. Describe the various methods for finishing concrete floors.
6. How may efflorescence be removed from masonry surfaces?
7. What are the advantages and disadvantages of continuous mixers and batch mixers?
8. What are the practical difficulties and disadvantages, in the operation of automatic measuring machines, of measuring the materials of concrete?
10. Describe the various methods of charging mixers.
11. Describe some of the methods of economically transporting concrete.
12. Make a sketch and plan for the concrete plant for a 6-story building, 40 feet by 100 feet; or, describe, with comments and sketch, the plant of some similar building actually being erected.
13. What are the advantages of using a portable concrete plant for laying the concrete foundations for pavements?
14. How would you wash sand when the magnitude of the work will not justify the employment of special machinery?
15. What methods are used to prevent the forms or centering from adhering to the concrete?
16. What precautions are taken to prevent the lumber in the forms from swelling or buckling?
17. How long should the forms and centering for reinforced concrete remain in place under various conditions?
18. What general principle must be followed to obtain the maximum economy in designing the forms for reinforced-concrete work?
19. Describe various devices for holding column forms together.
20. How are I-beams utilized to support the forms for concrete slabs laid on them?
21. Make an estimate of the cost of the forms for the building; described in Article 384.
22. Make a sketch design for the forms for a vertical wall ten feet high, six inches thick, and twenty feet long.
23. Describe the methods of lowering the centering under arches.
24. What are the proper dimensions for a hemlock beam carrying a distributed load of 6,000 pounds on a span of 12 feet, so that the deflection shall not exceed 1/8 inch?
25. What should be the dimensions of a column of hemlock 12 feet high, to support safely a load of 15,000 pounds?
26. Make up a bar list and sketches, similar to those of Figs. 175 to 180, with dimensions, for the bending of the bars in one panel as sketched in Fig. 109.
27. What are the several methods of bonding old and new concrete in floor construction?
1. Draw on a sheet of drawing paper four lines which are not parallel, and whose directions and lengths represent the directions and intensities of the forces. Then determine graphically the resultant of the four forces.
2. Draw four parallel vertical lines which represent the location, direction, and intensities of four parallel forces. Select two points, one on either side of the group of forces, which are to be considered as abutment points. Find, first, the position and intensity of the resultant of the four forces; and second, the amount of the vertical reactions at the two abutments.
3. Select some point within the equilibrium polygon of Answer No. 2, and find the pole, the force diagram, and the equilibrium polygon which shall pass through this chosen point.
4. Draw two lines which are not parallel, which represent the locations, intensities, and directions of two forces. Select two points in the same horizontal line as abutments, and find an equilibrium polygon which will hold these forces in equilibrium.
5. Select Another Point In The Diagram Of Answer No. 4, and draw an equilibrium polygon through it.
6. What is the distinction between a right arch and a skew arch?
7. The pressure on a masonry joint 50 inches wide by 12 inches thick is 120,000 pounds. The center of pressure is 15 inches from one edge. What is the maximum unit-pressure on any part of the joint?
8. Draw the intrados for a segmental arch with a span of 40 feet and a rise of 10 feet. Compute the proper depth of keystone; make the thickness at the abutment 1/4 greater, and draw the extrados. Use scale of 1/2 inch = 1 foot.
9. On the basis of Question 8, draw the load line, allowing for a level cinder fill, a 7-inch pavement, and a live load of 200 pounds per square foot. Use scale of 3,000 pounds per inch for load line.
10. Assuming 15 voussoirs in the above arch, compute the vertical loads on each voussoir, and draw a half load line for full loading over the whole arch.
11. Determine the special equilibrium polygon for the above loading, and the maximum unit-intensity of pressure at any joint.
12. Determine the load line for a concentrated load of 20,000 pounds on an area of 25 square feet at the quarter-point of the arch, and a load of 200 pounds per square foot over the remainder of the half-span.
13. Draw the special equilibrium polygon for the loading of Question 12, and determine the maximum unit-intensity of pressure at any joint.
14. Design an abutment for the above arch which shall be stable under either of the above conditions of loading.
15. Draw the load line for the above arch on the basis of the loading of Question 12, but on the assumption that the pressures on the arch are perpendicular to the extrados.
16. What is the essential distinction between a voussoir arch and an arch rib?
17. What are the three kinds of arch ribs, and what are their distinctive characteristics?
18. Assuming that the special equilibrium polygon for any loading has been determined, how do you determine the moment, thrust, and shear at any point of an arch rib?
19. How do you determine the moment of inertia of a rib section which is reinforced both top and bottom?
20. Redraw The Extrados And Intrados Of Fig 234 on the scale of 1/4 inch = 1 foot; and then, by scaling the various thicknesses at every two-foot section, for 26 feet on each side of the center, compute the moment of inertia for each section.