## Finding max bending moment

## Finding max bending moment

(OP)

Hi folks.

See file attached.

Its an simply supported beam with an concentrated force.

I cant program Mathcad to find the x value were shear force diagram intesects with x axis.

I know at wich value is this going to happen for this loading scenario but how to tell mathcad to slove this?

I tired using the root function but no luck.

Please help.

Thank you

See file attached.

Its an simply supported beam with an concentrated force.

I cant program Mathcad to find the x value were shear force diagram intesects with x axis.

I know at wich value is this going to happen for this loading scenario but how to tell mathcad to slove this?

I tired using the root function but no luck.

Please help.

Thank you

## RE: Finding max bending moment

TTFN

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## RE: Finding max bending moment

IRatuff I see that you noticed that Ive created an discontinous function is this the wrong way?

WOuld you do it someother way?

thank you

## RE: Finding max bending moment

TTFN

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## RE: Finding max bending moment

Please see file attached.

If I define a picewise linear function like in the file attached, I still have an discontinuity for the part were the graph is vertical.

So how to find these two values for x were the graph intesects with x=0?

Please help.

## RE: Finding max bending moment

## RE: Finding max bending moment

My goal would be that Mathcad spits 2 numbers out....in this case -1.5 and +1

## RE: Finding max bending moment

## RE: Finding max bending moment

http://s000.tinyupload.com/index.php?file_id=02292...

YOu can see that V(x) cuts the abscisa at 2 loactions.

I Know how to find one of them, but can Mathcad spit out both values if the egsist?

Thank you.

## RE: Finding max bending moment

YOuve uploaded 2 same files...

## RE: Finding max bending moment

## RE: Finding max bending moment

http://files.engineering.com/getfile.aspx?folder=a...

TTFN

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## RE: Finding max bending moment

So basicly you defined that vertical portion with an equation BUT it has an very,very small slope?

## RE: Finding max bending moment

Seem to work for this kind of problem

http://s000.tinyupload.com/index.php?file_id=04732...

Thank you.

## RE: Finding max bending moment

In previous egsamples i have a function V(x)=....

I can get an value of V for any given x that I type in th brackets.

Is it possible vice versa?

I wanta to know at wich x would V= defined value?

So bascily I would need to First type eg. V=20kN and then Mathcad would give value for x at wich V=20kN

Possible?

## RE: Finding max bending moment

x:=1 [initial guess for solve block]

given [required for solve block]

V(x) <CTRL>= xx [press the <CTRL> key and then the "=", resulting in a bolded equal sign, unless you've dinked with the fonts]

x := find(x) [or] find(x) = [the former assigns the found value of x to x, so that it can be used in subsequent calculation; the latter simply displays the found value, but x remains at the initial guess value]

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## RE: Finding max bending moment

one more question,see file attached.

http://s000.tinyupload.com/index.php?file_id=56723...

Is there anyway that I can condition the statement so that it looks for values belowe 4m and second statement for values above 4m?

## RE: Finding max bending moment

## RE: Finding max bending moment

> You need to change the guess value of x to be >4 -- for the second set of Finds

> Change find to minerr -- sometimes this works, and sometimes not - it worked a couple times on your sheet when I tried it, and failed most of the other times. The algorithms are all somewhat dependent on having continuous functions, so the discontinuous functions are very challenging

TTFN

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## RE: Finding max bending moment

minerr"Is this spelt corectly?

I get an error every time when I try this.

So the solution woul dbe to convert this discountnous function into what you suggested "very steeep slope"wich would make it continous,

## RE: Finding max bending moment

TTFN

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## RE: Finding max bending moment

=-20Kn will not work at all, there is no V(x)=-20Kn with x>4m## RE: Finding max bending moment

" You need to change the guess value of x to be >4 -- for the second set of Finds"this works fine at my place

thanx!