## AASHTO Spiral Reinforcing Area

## AASHTO Spiral Reinforcing Area

(OP)

Hi,

I need a quick thought on this design approach.

In the current AASHTO 8th Edition, the formula for calculating minimum transverse steel and for calculating member shear capacity due to transverse steel depends upon the value Av or Area of Transverse Steel. What is the appropriate value to use here for Spirals? Here are some choices... 2 * A, pi/2 * A or just A. Where A is the area of a single hoop bar.

Thanks!

I need a quick thought on this design approach.

In the current AASHTO 8th Edition, the formula for calculating minimum transverse steel and for calculating member shear capacity due to transverse steel depends upon the value Av or Area of Transverse Steel. What is the appropriate value to use here for Spirals? Here are some choices... 2 * A, pi/2 * A or just A. Where A is the area of a single hoop bar.

Thanks!

## RE: AASHTO Spiral Reinforcing Area

## RE: AASHTO Spiral Reinforcing Area

## RE: AASHTO Spiral Reinforcing Area

_{sp}is defined as "cross-sectional area of spiral or hoop", so the area of the bar, in the calculation of the reinforcement ratio.For calculating shear capacity, it's the total area of the bars crossing the shear failure plane. Therefore, it would be 2 * A

_{sp}, because the failure plane intersects the spiral twice for each space, just as you would count both legs of a stirrup or tie.I should add that I've never had to think about the shear capacity calculation, since every column I've ever designed had more than adequate shear capacity using the concrete alone.

Rod Smith, P.E., The artist formerly known as HotRod10

## RE: AASHTO Spiral Reinforcing Area

If circular stirrups (hoop) are to be used, then I would agree there are two legs in the shear plane, the same as the design of rectangle stirrups.

## RE: AASHTO Spiral Reinforcing Area

It's the same for spirals. Draw a column with a spiral. Now slice through the column at a 45

^{o}angle and see how many bars the slice goes through. I think you'll find it's the same as it would be for hoops or ties at the same spacing as the pitch of the spiral.Rod Smith, P.E., The artist formerly known as HotRod10

## RE: AASHTO Spiral Reinforcing Area

## RE: AASHTO Spiral Reinforcing Area

Rod Smith, P.E., The artist formerly known as HotRod10

## RE: AASHTO Spiral Reinforcing Area

Thanks for bring up the correct name of this method, yes, "volumetric" . I don't recall the limits on the applicability of using spiral reinforcement, but the beauty of this method is that, if permitted, after calculating the reinforcing ratio, by plug in a trail/desired As, the required spacing is thus determined. The shear force is no where in the design process, is it?

## RE: AASHTO Spiral Reinforcing Area

Rod Smith, P.E., The artist formerly known as HotRod10

## RE: AASHTO Spiral Reinforcing Area

## RE: AASHTO Spiral Reinforcing Area

## RE: AASHTO Spiral Reinforcing Area