Recent content by swmiami

I need to evaluate an existing building that was designed in 1958. A-30, A-37.5 and A-50 concretes were specified. Does anyone know the strengths? Thanks.

I inherited a project in which a 20ftx37ft post-tensioned slab shall be removed to create an opening. We hired a specialist and he contacted contractors. They will use "ground penetration radar" to locate tendons and use "impact echo scanner" to detect voids. If a conduit was not solidly...

When the beam deflects, its end will rotate. The load will shift to interior edge of the column (unless you place a narrow strip of bearing plate at the center of the column). I would either use an eccetricity of half the tube size or treat the connection as a moment connection and calculate the...

Pour another layer of concrete on top of the existing pile cap. Make them composite by roughening the surface and/or install dowels. Let the column sit on top of the new concrete. The tensile force in the "tie" is smaller with a thicker pile cap so that the required development length can be...

The straightened bottom bars will act as dowels. After chipping off concrete cover, the surface is rough enough to transfer shear. I wouldn't use additional dowels or bonding agent on the side surfaces.

If the rebars at the reveal locations are epoxy-coated, I think the concrete cover can be reduced. Any commnets?

Section 2.15.2 of ACI 551R-92 (Tilt-Up Concrete Structures) allows any cover dimensions between the required minimum for precast and cast-in-place concrete. I would use 1" for exterior and 3/4" for interior (not exposed to earth or moisture change). By the way, is there a set tolerance...

Full thickness should be used to calculate reinforcement for temperature and shrinkage. It becomes clear if you treat the reveal as a crack.

The "pull" method is simply a joke. When you stand on the WWF, your body weight prevents you from pulling up the WWF. If you can achieve the specified concrete cover in your way, it is your means and methods. If you cannot, it is non-compliance. I don't think bar chair is a practical way to...

If non-shrink grout is required, I will specify it continuously to get uniform support. Friction probably is not a concern because it is related to total vertical load and surface condition but not total contact area. Lutfi: It is interest to know that you lost every fight. Can you give more...

If Special Design Considerations in ASD Chapter K are satisfied, I don't see a reason that cap/base plates have to be used. ASD Section A4.2 specifies minimum load increases due to impact. Building codes should have similar provisions.

Do I need to specify non-shrink grout between tilt-up wall panel and footing? If not, any special requirements should I specify? Thanks.

Does "ignore the reveal" mean that rebars have less coverage at the reveal (if both faces are reinforced)? Will corrosion be a concern?

It appears that the minimum wall thickness (1/30) requirement for nonbearing walls in Section 14.6.1 of ACI318-05 is for wall designed by Empirical Design Method only (14.5), because there is no thickness limit if the wall is designed by Section 14.4 or 14.8. Can anyone confirm this and/or...