Test 2 - Print name K E‘r’ I have abided by the...

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Unformatted text preview: Print name K E‘r’ I have abided by the Virginia Tech Honor Code. Sign name CEE 3424 — Reinforced Concrete Structures I Fall Semester 2007 — October 30, 2007 Exam #2 1. Given a simply supported beam 40 feet long, carrying its own dead load plus 1.5 k/ft live load, what are good starting values for b, h and p for the design of this beam? (f’c = 5000psi and fy=40,000psi) (3 pts.) f/LL w 2, =» 40" w 48" L{Ala “’2 3M1» 40" VZOH ,OZDAQé—pza =s~2.‘>’/. 2. Give three reasons one might add compression reinforcement to a beam(3 pt .) "‘ Easier +9 Cows‘it‘oa‘i‘ 'fncrtau. 6H5“, z)’ ’ Reduce; \oM) ‘l‘erw dispkcemwu "IM‘Or‘ove. AUC7“\“*"( .— Mo mailer re a QFSA‘S 3. How many #6 bars can be placed in a single layer in the beam shown below?(4 pts.) lnside bend diameter is 4db for stirrups #5 and smaller Minimum clear spacing between bars in a layer is db, not less than 1 in. _! loo/so comet spmrwm? x; “3— Z(.7$+.l.zs+ L243 = l0.’lS“ 5’4 Spa-calms ‘ l"+ 71$“ a HS“ 073 S: [If-.2 érl4 spaces Os 7 bars 4. For the following beam, a=6.64 in. what is the q) (phi) factor? (5 pts.) f’c = 6000 psi, fy = 60 ksi 5. What is the minimum area of steel that ACl alloWs to be placed in the beam in problem 4?(5pts.) ‘ 3E1 M“ “5“ Ann" 7'; L9“ *&\\Mfi\i5 L:I\\'YO\S l, '\ ‘ 2 '\ ASK“: éoaoo ' Z ' ' m 6. Consider the following beam (20 pts): WOW f'c = 8000 psi fy = 60,000 psi concrete unit weight = I50 pcf =l 500 lb/ft 28" IIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIi AS ’ 30.0" m a) What area of steel (A5) is required for this beam? 3 I‘\,~\ to '28 , "7 7/ we ‘24 “50- W 4+ V l‘ i’vh‘f:\“\ -, l.$xl.'o+ ,z‘im l.?. = 2.75 /F+\/ Us to will 2.19301: 3041.4 .09 = 31l251n-L) MM ‘5'; “T” +OJ‘CAQJV Mn' N / our—a -. 28-3 t 75 <9 4lZe _ _'z. A5 " 60; 9'75 25 ’ (KEV) b) Select bars assuming 1.5 in. clear cover and #3 stirrups. Indicate number of layers required for your bar selection. 4 #8 Km 2 .47“; 2T\) Q 1‘7 in Z layer} c) After selecting bars, what other checks should be made? (just list checks) O‘chmi A 7. Does the compression reinforcing in the given beam yield (20 pts) ? :25 3 e0. #6 f'C = 5000 psi fy = 60,000 psi e0 #l0 Assum Q0Wr€$§§ DR. \lK‘ekAS . 7.. '5: A‘“: LSZM A$L¢ Afi'AS\=' IO.|L0\I\1“\u3Z : ~\V‘\ 854x190 55, ...... “a! : .flsfléx l4 — “n .1 8m - ‘ ____ 0W ‘ C, é» H.\4m ‘25“ 003 ‘ _ 2c : 1003 L4) U“ 5 (M | . \ = ( 25 .0023 / yes, 133-“ = 0021 53 3' 20000 ’ A 8. The tension reinforcing in the following beam DOES NOT yield. What is the nominal moment capacity (M) of the beam? (20 pts) f'c = 3500 psi fy = 60,000 psi 44 .0260} '+ l086776a - 25015235 :— o 7' Z433¢x - $37.7 =00 no MW ’6 ’goffiu‘fl A; 0615 Mth ~l$ / «l9 lzioz. Amin r M Wok Vt2 (6 9. What are appropriate optimized b and h for a simply supported beam spanning 18 ft, carrying an unfactored live load of 2 k/ft, its own self-weight and an additional 0.8 k/ft dead load? Use f’c = 4000 psi, fy = 60 ksi and a reinforcement ratio of 0.014. Start with a beam 18 in. deep by 9 in. wide. (20 pts.) 09/ 90560.6; ‘31: “So: {98,75 94' i4+ la“ w“; 1.2( .8+.ies1s\+i.b(2\ = 4.54,?) 4+ M : 4W : ‘79:ng g ZIZO‘M’LC?) fl: 2‘33- BSQxA-LCZ? Mn’, 4;: 'q " 9% Mr; K = G (go /\\\ 3“ ~ \. “9’4" alto \ w ' 4— = 1 23$; 3 M EA ‘ 4(,2loXl—,5‘i('zn) lo .\ t\ / l 2 X l ham-n 9L WI / l u \l K / 10 X Zl m it w k M; was ...
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Test 2 - Print name K E‘r’ I have abided by the...

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