You personally designed the formwork for a 14’‐0” tall concrete wall as specified below: 3/4” Sheathing (Class I, B‐B Plyform) 2x4 studs spaced at 12” o.c. Double 2x4 wales spaced at 30” o.c. Form ties have 3,350‐lb capacity (safe working load) and they are spaced 24” o.c. horizontally along the wales with 2” x 6” wedge plates (assume 1⁄2” gap between wales). Lumber is Douglas Fir‐Larch, No. 2 grade 7‐day construction load is valid (short‐term use, limited reuse) Members were assumed continuous over 3‐spans Deflection was limited to L/360 Plywood orientation assumed in the strong direction Concrete mix is normal weight, Type I cement with no retarder Mix temperature was assumed to be 60°F Rate of placement is 3 ft/hr Consider the following variations noted below and specify whether the form design is adequate or not in each case. For each case, you can stop your check at the first sign of failure. If, on the other hand, all pertinent checks prove acceptable, you should deem the design adequate. Consider each case independently. That is, part (c) has nothing to do with part (a), and so on. The concrete plant uses retarders in the mix 3,000 lb ties are used instead (Remember, part (a) above has nothing to do with this part. Consider all cases independently of one another). 7/8” plywood was used instead of 3/4" (good) but it was mistakenly installed in the weak direction instead of strong (bad) Mix temperature is colder than expected, 50°F instead of 60°F Unfortunately the contractor doesn’t have No. 2 lumber on hand. Rather than having to buy newlumber,he/shewantstouseoldconstructiongradelumber. However,the construction grade lumber they want to use has been used significantly in the past (i.e. not the best quality), therefore the conservative assumption is for you to use CD = 1.0 (not 1.25).
You personally designed the formwork for a 14’‐0” tall concrete wall as specified below:
-
3/4” Sheathing (Class I, B‐B Plyform)
-
2x4 studs spaced at 12” o.c.
-
Double 2x4 wales spaced at 30” o.c.
-
Form ties have 3,350‐lb capacity (safe working load) and they are spaced 24” o.c.
horizontally along the wales with 2” x 6” wedge plates (assume 1⁄2” gap between wales).
-
Lumber is Douglas Fir‐Larch, No. 2 grade
-
7‐day construction load is valid (short‐term use, limited reuse)
-
Members were assumed continuous over 3‐spans
-
Deflection was limited to L/360
-
Plywood orientation assumed in the strong direction
-
Concrete mix is normal weight, Type I cement with no retarder
-
Mix temperature was assumed to be 60°F
-
Rate of placement is 3 ft/hr
Consider the following variations noted below and specify whether the form design is adequate or not in each case. For each case, you can stop your check at the first sign of failure. If, on the other hand, all pertinent checks prove acceptable, you should deem the design adequate. Consider each case independently. That is, part (c) has nothing to do with part (a), and so on.
-
The concrete plant uses retarders in the mix
-
3,000 lb ties are used instead (Remember, part (a) above has nothing to do with this part. Consider all
cases independently of one another).
-
7/8” plywood was used instead of 3/4" (good) but it was mistakenly installed in the weak direction instead of strong (bad)
-
Mix temperature is colder than expected, 50°F instead of 60°F
-
Unfortunately the contractor doesn’t have No. 2 lumber on hand. Rather than having to buy newlumber,he/shewantstouseoldconstructiongradelumber. However,the construction grade lumber they want to use has been used significantly in the past (i.e. not the best quality), therefore the conservative assumption is for you to use CD = 1.0 (not 1.25).
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