| 1. |
There are basically 4 types of structural framing systems for the bridges, simple span, continues spans, cantilever and suspended spans, and rigid frame. |
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True |
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False |
| 2. |
The substructure includes those parts, which transfer the loads from the bridge span down to the supporting ground. |
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True |
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False |
| 3. |
Abutments are substructures supporting the end of a single-span or the extreme end of a multi-span superstructure and usually retaining or supporting the approach embankment. Typical abutments are shown in fig 3-2. |
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True |
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False |
| 4. |
Piers transmit the load of the superstructure to the foundation material and provide intermediate supports between the abutments. |
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True |
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False |
| 5. |
Bearings transmit the superstructure loads to the substructure, and they permit the superstructure to undergo necessary movements without developing harmful overstresses. |
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True |
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False |
| 6. |
Dolphins and fenders around the bridges protect the structure against collision by maneuvering vessels. |
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True |
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False |
| 7. |
The surface appearance of cracks on the bridge can give the first indication of the cause of cracking |
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True |
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False |
| 8. |
Figure 5-1 shows a typical Pattern or Map crack, which are the result of restraint of contraction of the surface layer or possibly an increase of volume in the interior of the concrete. |
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True |
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False |
| 9. |
Figure 5-2 shows D-cracking, these cracks usually start in the lower part if a concrete slab adjacent to joints, where moisture accumulates and progresses away from the corners of the slab. Vertical cracks near vertical expansion joints in the abutments and walls can also be classified as D-cracks. |
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True |
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False |
| 10. |
The individual cracks that run in a definite directions and may be multiple cracks in parallel at definite intervals, indicate tension in the direction perpendicular to the cracking. |
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True |
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False |
| 11. |
Spalling is defined as the development of fragments, usually in the shape of flakes, detached from a larger mass. Spalling differs from disintegration in that the material being lost from the mass is concrete and not individual aggregate particles that are lost as the binding matrix disintegrate. |
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True |
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False |
| 12. |
Table 5-1 summarizes the various causes of: |
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Deterioration in concrete |
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Spalling |
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Soil erosion |
| 13. |
Which one of the following could be cause of deterioration in steel bridges? |
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Air and moisture |
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Industrial fumes |
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Deicing agents |
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Seawater and mud |
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Thermal strain or overloads |
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Fatigue and stress concentration |
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Fire |
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Collisions |
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Animal waste |
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Welds |
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Galvanic action |
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All of the above |
| 14. |
While timber is not as strong as steel, it approximates ordinary concrete in compressive strength. It’s rated strongest in flexural strength. Timber has an allowable compressive strength (parallel to wood grain) of about 75 percent of the flexural value. Perpendicular to the grain, compressive strength is only 20 percent of the flexural strength. Horizontal shear is limited to 10 percent of the flexural strength. |
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True |
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False |
| 15. |
Common rules for timber repairs are:
- There should be at least 1/8-inch clearances between the timbers to allow the timber to dry properly.
- When native logs are used for construction, all bark should be removed to reduce moisture penetration into the logs.
- Green or wet timber shrinks considerably when seasoned. Repeated wetting and drying also causes dimension changes as great as 5 to 10 percent in the direction perpendicular to the growth rings. Frequent re-nailing and tightening of bolts is necessary.
- Care should be taken when using new and salvaged wood together to carry loads because of a difference in the sag and shrinkage of the members. The repair should avoid using new and old stringers in the same panel.
- Wood shims or wedges should be made from heart cypress, redwood, Douglas fir, or of the same material as the member.
- Replacement members must have the same dimensions as the existing member accounting for shrinkage.
- Always treat drill holes and cut ends, to prevent water or insect damage.
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True |
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False |
| 16. |
When lumber is damaged to the point that the structural integrity of the member is in question, scabbing or slicing of the member may be required to bridge the damage. |
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True |
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False |
| 17. |
In method of flexible sealing repair of a crack in concrete, it involves
routing and cleaning the crack and fitting it with a field-molded flexible sealant. It is used for active cracks in which the crack is the indication of a joint requirement in the concrete, and the formation of a joint does not impair the capacity of the structure. |
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True |
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False |
| 18. |
Stitching is the process of drilling holes on both sides of the crack and grouting in stitching dogs (U-shaped steel bars with short legs) that bridge the crack. |
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True |
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False |
| 19. |
Stitching is used to re-establish: |
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Tensile strength across the crack |
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Compressive strength across the crack |
| 20. |
The typical repair involving concrete columns and piles is to place a concrete jacket around the member to protect it from further deterioration or to restore the structural integrity of the member. The repair can be made with a standard wood or metal formwork, which is removed after curing, or fiberglass form that remains in place and helps protect the surface of the member. |
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True |
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False |
| 21. |
The large variety of crack types prevents a single repair method. Active cracking may require strengthening of the concrete across the crack to prevent further crack expansion and the application of a flexible sealant that will expand with the crack. Dormant cracks basically require bonding across the crack for the load carrying portion of the concrete and sealing in all other areas. |
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True |
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False |
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