Box Culvert Design Using Visual Basic-6.0 (Part-6)

= 0.5*0.12*8.75

= 0.525 k/ft

3.1.7 UPWARD SOIL PRESSURE :

Upward soil pressure at the bottom slab may calculated from the following-

1. From top slab including fill

= 0.1125 + 0.672 + 0.02

= 0.8045 k/ft²

2. From vertical wall

= ( 2*0.75*0.15*4 ) / length of culvert

= ( 2*0.75*0.15*4 ) / ( 2*0.75+4*1 )

= 0.164 k/ft²

3. From wheel load

= 1.1428/length of culvert

= 1.1428 / ( 1*4+2*0.75 )

= 0.21 k/ft²

4. From bottom slab

= 0.75*0.15

= 0.1125 k/ft²

5. Water pressure = 64*4/1000

= 0.26 k/ft²

Total vertical pressure on foundation soil

= ( 0.8025+0.164+0.21+0.1125+0.26 ) k/ft²

= 1.55 k/ft²

3.1.8 LOAD ON BOX CULVERT :

1. Top slab load (uniformly distributed) = 0.81k/ft

2. Top slab load (concentrated),

Rear wheel = 1.1428 k/ft

Front wheel = 0.2857 k/ft

3. Bottom slab load = 1.55 k/ft

4. Side wall load at top = 0.525 k/ft

5. Side wall load at bottom = 0.81 k/ft

6. Surcharge load = 0.156 k/ ft

3.1.9 CALCULATION OF DISTRIBUTION FACTOR :

Moment of inertia,

IAB = bh³ /12

= 12*9³ /12

= 729 in⁴ [consider 1 ft strip]

Stiffness,

kAB =I/L [center line dimension]

= 729/57

= 12.8

IAB = 729 in⁴

KAB = 12.8

IAC = 12*9 / 12

= 729 in⁴

KAC = 729 / 57

= 12.8

Distribution factor,

DAB = 12.8 / (12.8+12.8)

= 0.50

DAC = 12.8 / (12.8+12.8)

= 0.50

DBA = 12.8 / (12.8+12.8)

= 0.50

3.1.10 CALCULATION OF FIXED END MOMENT :

MAB = -wl² /12-Pl/8

= -0.81*4.75² /12-1.143*4.75/8

= -2.202 k-ft

MBA = 2.202 k-ft

MAC = Pl² /12+wl² /30

= (0.156+0.525)*4.75² /12+(0.81-0.525)*4.75² /30

= 1.49 k-ft

MCA = -Pl² /12-wl² /20

= -(0.156+0.525)*4.75² /12-(0.81-0.525)*4.75² /20

= - 1.6 k-ft

MCD = wl² /12

= 1.55*4.75/12

= 2.91 k-ft

MDC = -2.91 k-ft

Category: AASHTO, abutment, Box Culvert, Box Culvert Design, Comuter Aided Design, Culverts, impact moment, Visual Basic