Box Culvert design analysis
Current time: 10-18-2018, 08:36 AM
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Author: shabas
Last Post: chigozie
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Box Culvert design analysis
#1
Is there any example of box culvert design ie. calculations and analysis?

Is it possible to analyse using ETABS or can anyone suggest the best method to design the culvert with aircraft loading?

tq.
.
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#2
Dear shabas,

I recomend you use the Sap 2000 your project.
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#3
Usually our company use ETABS and SAP2000 for very big size culvert. For small culvert then u can just use high strength bar 12 Dia. at 150 spacing with a thickness of 150-200mm.
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#4
In my opinion, the most suitable software for design of box culverts and all other structures in which inplane forces act, is STRAP. Because only STRAP considers inplane shell forces and design reinforcement for this. All other software ignore inplane forces. Therefore, design of box culerts, Overhead Water Tanks, shells structures, concave or convex slabs etc must be designed on software that considers inplane shell forces during design of reinforcement.
Hafiz M. Abdul Hayee
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#5
Dear Hafizmah,

I got no idea on STRAP software. However, i am not agree with what u've stated in plane force. Are you clear about in plane and out plane forces?
Personally, i don't think there is in plane force in box culvert, water tank and etc.
In box culvert or water tank (Buried), Earth pressure and GW will create an out plane force in the wall but not in plane.
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#6
Hi Techno,

A box culvert will have some in-plane forces. The wall will have axial force from the vertical load of soil , live load surcharge and self weight from top slab. The horizontal earth pressure / water pressure will be resist by top & bottom slab and this will induce axial forces too. Both are in-plane forces.
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#7
Ya, you are right about the slab which will have in plane forces.
However, what i am talking about is the wall which is subjected to out plane forces but not the slab.
In additional, even if the slab is subjected to some in plane forces but it's negligible.
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#8
The wall will have axial force (in-plane ) from the top slab self weight, vertical soil cover loads, vertical surcharge live load too. But of course under normal condition bending of wall will still govern the design but we should not simply ignore the in-plane forces.
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#9
To answer refer to Post: #1: Shabas as follows:

I am familiar with designs relating with box culverts or underpass bridge, especially for highway and railway track.
Generally I did simple calculations with 2 dimensional frame and I assume spring as soil bearing at bottom of the box. The value of spring see table 9-1 "Range of values of Modulus of Subgrade Reaction ks" in Foundation Analysis and Design, Bowles, page 409.
About distribution width for live load: There are many books or design specification explaining about equivalent width for example in AASHTO LRFD Bridge for one lane of highway with 3600mm width, the equilvalent width may be determinded as E=2440+0.12 S. S=Clear Span.
The distribution reinforcement placed in the bottom of all slabs transverse to the main reinforcement and this amount of distributin may be determided by percentage of main reinf = 55/sqrt(L), L is clear span.
Other minor reinforcement is determined based on the allowable width of crack.
About earthquake loading is neglected, especially for box culvert.
I used to use SAP software to design the box frame. And I think all the structure softwares are as good as SAP. Now depends on the designer how to determine the soil spring parameter dimension, reinforcement arrangement and allowable deflection based on the code used in your country.
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#10
Thanks for all your replies.

Can anyone guide me on how to analyze & design box culvert using ETABS or SAP2000?

Appreciate for your help.
.
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