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Re: modulus of subgrade reaction

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Arman,

Mabuhay ka rin!

Modulus of subgrade reaction is just a conceptual relationship between soil pressure and deflection. The basic equation for this using plate load data is:

              soil pressure
        Ks = ----------------- ( Kn/m2/m)
              soil deflection 

Often, we see the unit of modulus of subgrade reaction as Kn/m3, which mistakenly defined as unit weight of soil. Through the equation we can easily understand its definition. It's true that geotechnical report usually gives information regarding soil strata, recommended sol bearing pressure and at the same time recommends the kind of foundation that is best for your structure. Geotechnical engineer's job does not end with his report. As long as you need information/data, for the success of your project, feel free to ask the soil engineer. In the first place, he's job is to support the structural engineers. So, if you cold ask him the deflection capacity of your soil, which I believe he could give, then your problem is solved. Bye! bye!

Its me!

Jonathan G. Sevilla, CE
Trans-Agalma Group  
PHILIPPINES


seaint(--nospam--at)seaint.org wrote:

>John,
>
>mabuhay!
>
>i used to be a design engineer with dccd engineering corp, and if i'm not mistaken, i think dccd has worked with ove arup on several projects, but that was way before my time with dccd.  i know this because i've seen reports in the office with ove arup's name on them.
>
>now, i am with globe telecom, as a safety engineer in the engineering and research section.  among my duties is to perform tower and building investigations and design.  
>
>for tower isolated footings, you're right, they're fairly easy and simple to do.  but when it comes to design and evaluations of mat foundations for towers and buildings, i have to rely on staad, and the input it requires in order to analyse mat foundations is the modulus of subgrade reaction.
>
>when were you last in the philippines?  
>
>arman
>
>seaint(--nospam--at)seaint.org wrote:
>
>>
>>Arman,
>>
>>I have been involved in several high building design/analysis in Philippines
>>(where I worked with Ove Arup, phils) where mat footings are the typical
>>foundation, and , yes, in geotechnical reports there recommends the approx.
>>soil bearing capacity of the soil, but you could also request from them the
>>approx modulus of subgrade reactions ...
>>
>>but just thinking, you are analyzing self-supported comm towers, I think you
>>could just use simple statics to design the foundation ?..
>>
>>by the way, currently what company are you working with now?
>>
>>cheers, mabuhay...
>>
>>
>>John E. Alcaras
>>PE(Civil) MASEP
>
>
>__________________________________
>www.edsamail.com
>
>
>

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