Precast - CIP Composite Deck Analysis

[justhumm]

I am trying to rate/analyze an existing concrete dock.

The dock is composed of precast, pre-stressed concrete panels (6+ inch thick, 5000 psi, one-way slabs) simply supported on pile caps.

The precast panels have composite stirrups and there is a Cast In Place, reinforced deck (7 in thick, 3000 psi) poured on top of the panels. The dock was built in the early 1960s.

Does anyone know of a valid, tried method of analyzing this sort of structure (without making to many assumptions or over-simplifications)?

...or does anyone know of a readily available reference that might deal with this?

Thanks.

 

[asixth]

In our office when designing these highway structures (assuming it is a highway structure) we design for all stages of construction but you will only be concerned with the in-service loading.

The best design references will be AASHTO, this code will explain emperical distribution factors for live loads and explain a bit about using a more detailed mathematical representation of the structure. Another good reference material is the PCI bridge design manual which is available for viewing online.

When performing an analysis of the structure you have described, we perform a grillage analysis using beam elements.

If the composite prestressed panel-slab section does not exceed its cracking moment, you can model these as longitudinal spanning elements assuming full flexural stiffness and torsional stiffness assuming that flexural and torsional cracking will not occur. If cracking does occur, you will need to reduce the stiffness.

Because there will be curvatures developing transversely along the bridge, you will need to model transverse slab elements, the slab in this direction will exceed its cracking moment so the elements that you will need to reduce the stiffness in this direction to account for this. I recommend using 0.6*Ig.

The purpose for this grillage analysis is so you can determine how the point loads from traffic are distributed to each precast panel/slab section.

Once you determine this you can design the section for ultimate strength based on the code you are using. You will also need to look at service stresses and the deflections under some traffic loading.

Let us know how you go.