Calculation Report for Box Culvert Rebar | Structural Load ...

CALCULATION REPORT FOR BOX CULVERT REBAR Rebar calculation use SNI Beton 2002 as guidance. Concrete box culvert dimension sketch is described below. 1,2 m

0,3 m 1m

1. Applied Load Loads that work and affect box culvert strength are described below.  Self-weight of box culvert structure  Rigid pavement thick 20 cm  Trailer 12 m tire load 2. Calculation a. Load Calculation  Load weight from box culvert slab thick 30 cm (using reinforced concrete specific weight 2400 kg/m3). 𝑊𝑠𝑙𝑎𝑏 = 0,3 × 2,4 𝑡𝑜𝑛/𝑚3 = 0,72 𝑡𝑜𝑛/𝑚2

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This load multiplied by 1,2 as self-weight safety factor according to SNI Beton 2002 so w slab become 0,86 ton/m2. Load weight from rigid pavement thick 20 cm (using reinforced concrete specific weight 2400 kg/m3). 𝑊𝑟𝑖𝑔𝑖𝑑 = 0,2 × 2,4 𝑡𝑜𝑛/𝑚3 = 0,48 𝑡𝑜𝑛/𝑚2 This load multiplied by 1,6 as live load safety factor according to SNI Beton 2002 so w rigid become 0,77 ton/m2. Load weight from trailer 12 m tire load (using 1.2.3 axle configuration). 60 𝑡𝑜𝑛 𝑃𝑡𝑖𝑟𝑒 = = 5 𝑡𝑜𝑛 12 0,5 m

0,25 m

0,5 m

0,25 m 0,9 m

Rigid pavement 20 cm

0,65 m

5 𝑡𝑜𝑛 = 8,6 𝑡𝑜𝑛/𝑚2 (0,9𝑥0,65) 𝑚2 This load multiplied by 1,6 as live load safety factor according to SNI Beton 2002 so w tire become 13,76 ton/m2. 𝑊𝑡𝑖𝑟𝑒 =

Total structure uniform load is (0,86 + 0,77) x 1,2 = 1,96 ton/m. Total vehicle uniform load 13,76 x 0,65 = 8,94 ton/m. Total uniform load at box culvert upper slab (q) is 1,96 + 8,94 = 10,9 ton/m. b. Rebar Calculation Part of culvert which will receive the maximum moment load is its upper middle slab. Field moment at that position needs to be calculated.

L = 1,2 m

1

1

Load field moment = 8 × 𝑞 × 𝑙 2 = 8 × 10,9

𝑡𝑜𝑛 𝑚

× 1,44 𝑚2 = 1,96 𝑡𝑜𝑛. 𝑚

Load ultimate moment = 1,5 𝑥 1,96 𝑡𝑜𝑛. 𝑚 = 2,94 𝑡𝑜𝑛. 𝑚 Box culvert structure : Thick design = 30 cm Span = 120 cm Concrete compressive strength design = 300 kg/cm2. Capacity moment = 0,1131 x 300 kg/cm2 x 120 cm x 30 cm x 30 cm = 3.664.440 kg.cm=36,64 ton.mcapacity moment overwhelms load ultimate moment (OK). Rebar area calculation : 𝐴

𝜏

𝑤 = 𝐵𝐻 = 0,13 𝜏 𝑏𝑘 × 𝐵𝐻 𝑎𝑛

𝜏𝑏𝑘

𝐴𝑟𝑒𝑏𝑎𝑟 = 0,13 𝜏

𝑎𝑛

300

× 𝑠𝑝𝑎𝑛 × 𝑡ℎ𝑖𝑐𝑘 = 0,13 0,87∗4000 × 120 × 30 =

4035 𝑚𝑚2. Number of rebar needed : Rebar use for box culvert structure is D16 with bar area 201 mm2. 𝐴𝑟𝑒𝑏𝑎𝑟 𝑛𝑢𝑚𝑏𝑒𝑟 𝑜𝑓 𝑟𝑒𝑏𝑎𝑟 = 𝐴𝑏𝑎𝑟 4035 𝑚𝑚2 𝑛𝑢𝑚𝑏𝑒𝑟 𝑜𝑓 𝑟𝑒𝑏𝑎𝑟 = = 21 𝑏𝑎𝑟𝑠 𝐷 16 201 𝑚𝑚2 1200 𝑚𝑚 𝑆𝑝𝑎𝑐𝑒 𝑏𝑒𝑡𝑤𝑒𝑒𝑛 𝑏𝑎𝑟𝑠 = = 115 𝑚𝑚 21/2

Space used is 150 mm. (Since the safety factor between moment capacity and load ultimate moment is great enough, thus reducing the number of D16 rebar needed to 16 bars-8 bars above 8 bars below). 3. Summary Based on calculation above, box culvert should be used on site is illustrated below. Concrete K-300 1,2 m D16-150 D10-150

1m