Question

Determine the required footing thickness and design the reinforcement for the combined foot ing shown in Figure 10.30. Use concrete with f-3,000 lb/in, and reinforcing steel with f, = 60 k/in2. P 200 k Po=400 k 12 in square 18 in square 2.5 15' 7.5 Footing Width, B = 9 ft Figure 10.30 Combined footing for Problem 10.15

Answer 1

Size of fooings ft gft Avea of footing : 26Kg : 225 ftl - 20.903 2n® 20okip 4854 uere Ci C2 Co- of foobiny 1S 4.512m 15.286 2-5 Tte cessy that the sestaut of the lond f two Columns and the centroid dftie foot,ng Coincide so thst a uniform didribition of soipsue s abtained sibtion oSo essue is ncd え、200x0+ 400x15 600 2 ualto equr@ e sail pressune be unior Considening fooling as wele beam of R: gft: 2.7432m : The in longitudinal dechion, the unitomly didvilbited lond 24 k/ft 350.16 kNlm 25

42 p 162 4.572m 2-286m 918-153 226 12.5665-d),ワ b=6.2296 + %) 서 26 822 SFD (KN) 2.1954m 622 118 52.9 1.046 01 6592 914 ,932 Shefot 蚌剂卡 终1779.2 350.16 一2-276 " - te becomes za owing T456:2000f3 ksi 2o MFf6oksi-45M Depth of footing for gesicting monent Caslte value ム:415MPa 니

oting equi red Gviical cection frs one wy sheas y frm nte of the support wi be at ditante In given case mose shear is at colunn C2, Shear at d diston te from face of 2, e-5-) 0T8.153 2-7951 92 1542 349.952dN , . 0-15% meinhte ment in the footing slab, Assuming f the she0% is D28 MPa stre ngth of ftC 20 MPa Con tret. i-e. 20 C Table1, 73, 456 :200 . Shear ahength of section - () Footing to be cale m ,nc nay she an, O-28 x 2.7432xdx10, 898.1542-345-3529d 2, Calculaling desth of oting vewintd for punching shear Coica section punth shea be distance

ooting e same 0-3042 M 04512 Fors column CL Shea force 0:30 IR +虫)m from centre of Column CL 622 178 (11169- 03048d 2. 2. (563.3641 7.2429 N 918.153 2-795 x 275)-5 d 2 2- 293 1542976 N ause 3h63, PShont sil ofcolumin Gluma Sidle >T Column I 11 x3 kta

Punching area at cI c3+d)xd a C Runching ehess af face of clumn , Tunh 569-3641 175.24294 44 (0 30448+d)d Punching cress te of Colunin C2 1542 14916ud Fo foting tobe safe fos punching shears 1-112x103 冫(569-3641-175.2429 d ) → 4C0 308d) d 4412 d218.5d964 7o d24211 5 298.1542-17 9164 4472d2+729-5748d-PJ8.1542 ΖΟ -6

cfing eonu Hence, povide deft- 21omi Concicleing clears Coves 50 p b an size = 25 mm dia. 275-0 25 ovided Hente sechion is undeseinfoeced he know 46 My for bd2 Aste tve 4. E к g14 . 9324X106 2oxlooox 81252 20 K 1 000 x212 ,5 e 21 3418-9638 MM [Clause 26.6 .23ps 4 19 Li50 Ast tve

Provide 朿25 @ 160mmcle longitudinally ot batねmt m CIC (贞26@ 5.5" cle) 2.0 As 2x415 = 1601-2578 mm2- -R ovide奀)6@ 115 mm cle. Jong Udin ally ot ぼ帖@ 4.5., clc) top fooli in ơlker iAd 26X9 e mett width of foting) 9 2-7432 ke to HN Mone nt(desan): Wx1·2192 2 2 : 943949 kN·m 4x10 o 18x2DX 1000 424 m2 -' . section is unders-TUM