I don't care if you put plywood between your built up beam.......

[mark handler]

Question here....If plywood does not add any structural value then how do TGI floor trusses work?

They do add limited structural value. The question is, can you quantify it without quality controled conditions; ie: field conditions?

And Should the higher values be used without Engineering calculations, No.

 

[Mac]

Short strips of plywood don't add significant structural value.

Floor trusses have been engineered and evaluated.

 

[mark handler]

Flitch Beam Design & Software

http://www.strucalc.com/general-engineering/flitch-beam-design-software/

Accurate Flitch Beam Design Made Easier with Software

Flitch beam design software is a useful tool for architects, engineers, designers, and builders. Flitch beams are a common type of composite construction. Composite construction materials are formed by combining two or more materials in a way that allows them to function as a single component structurally. Flitch beams are created by layering wood beams with steel plates or plywood in order to form a wider, lighter structural beam. Bolts hold the layered components together to form a single unit.

These advantages make flitch beams a desirable and attractive choice in light frame construction projects:

•they can support heavier loads over longer distances

•are thinner than solid wood or steel beams with similar load-bearing qualities

•can be nailed to other components of wood structures during construction

•are much lighter than solid beams.

Using computer software to design a flitch beam can greatly improve the cost effectiveness of a project by allowing for a more exact and efficient design. Software packages precisely calculate the needed thickness, depth, and length of each beam much easier than any kind of hand calculation.

Utilizing flitch beam design software eliminates the possibility of using beams that are too thick or too closely spaced together. This can drastically reduce construction costs by allowing each beam to be more fully utilized to its capacity.

One of the more difficult calculations associated with a flitch beam is that of the Deflection the beam will undergo. Software packages will carefully calculate the deflection of flitch beams. Properly constructed flitch beams ensure that all of the components deflect by exactly the same value. The relative stiffness value of steel and wood is vastly different. When used correctly, structural analysis software will accurately determine the proper interaction of multiple materials.

Bolt size and Spacing in the construction of flitch beams is crucial. A separate article will briefly discuss a simple way of determining the bolt spacing for a flitch beam.

Flitch beam design software is a must-have tool for the careful architect, engineer, or designer.

 

[peach]

Flitch beams have been used for a hundred years.. the headers have rarely been the point of failure (of course, they weren't garage doors). It's standard practice (with the exception of a double stall garage door).

 

[Lou Marks]

Plywood does add strenght, however,one must use structural grade. The amount is negilble and not worth the effort. <5%, depth is the key to increasing spans and loads in most cases. Cheaper to use engineered wood or flitch plates. Mostly the plywood is the to make the beam the same width as the wall.

 

[jar546]

Plywood does add strenght, however,one must use structural grade. The amount is negilble and not worth the effort. <5%, depth is the key to increasing spans and loads in most cases. Cheaper to use engineered wood or flitch plates. Mostly the plywood is the to make the beam the same width as the wall.

I agree. The point of the OP was essentially this:

Do not use a (3) 2x10 with plywood between the lumber when prescriptively a (4) 2x10 is required then tell me that the plywood adds enough strength to make up the difference UNLESS you have an engineer's stamp to go along with it.