3. Presentation by Dr. Dutta and Notes on the Presentation
Dr. Dutta explained the scope of his work was limited to literature search, inquiries to the
manufacturers concerning their product, some limited testing on the materials to verify
manufacturers claims on vinyl and to address some of the concerns expressed in the ECB on
vinyl. Dr. Dutta indicated that the scope of his work did not include coming up with a design
procedure for designing safely vinyl sheet piling for flood or hurricane protection applications nor
to answer the functional concerns with respect to excessive deflection, vandalism, resistance to
damage from fire that were also expressed in the ECB. The following were some of the highlights
of Dr. Dutta's presentation and ensuing discussions:
a. Creep is an issue that must be considered when using vinyl. Creep is movement that is time
dependent. Where there will be sustained loading over time this must be considered in designs
when vinyl is used.
b. Vinyl sheet piling is a weak material when compared with steel sheet piling. It has a modulus
of elasticity of roughly one percent of steel and a tensile strength of roughly 10 percent of steel.
There is approximately four times the elongation of vinyl to the elongation of steel to reach each
material's breaking strength respectively.
c. Vinyl sheet piling is subject to degradation (brittleness) with respect to resistance impact
loading over time. One manufacturer indicated a 40 per cent reduction in resistance to impact
loading with time (50 year life). This issue would need to be addressed along with a load case
criteria established for impact when considering vinyl because of this degradation and the
weakness of the material. Normally impact loads are not design considerations for steel or
d. Because of the low material strength of vinyl, low resistance to creep, and the fact that the
material behaves non-linearly, deflection is an even greater concern when using this product.
Therefore any design must assure that deflection is not to the magnitude that would impair the
function of the vinyl floodwall and the design procedure must be sophisticated enough to model
accurately the deformations causing the deflections. It was noted that USACE policy criteria
requires a flood or hurricane protection wall to be capable of performing successfully with water
to the top of the wall on the unprotected side of the wall. However it was discussed that deflection
due to creep may not be a big problem for floodwall or hurricane applications since these loads
are normally short term duration over the life of the project.
e. Testing conducted by Dr. Dutta and his associates as well as research of existing vinyl
applications did not show significant degradation of tensile and flexural strengths of vinyl with
time. UV radiation and boiling tests were both conducted in conjunction with this determination.
f. Literature search showed that different manufactures have different safety factors they use in
giving the safe loading capacity of their product. There are no industry standards on how to
qualify the capacities of the vinyl sheet piling sections nor how it is manufactured. Some of the
manufacturers responses to Dr. Dutta's questions point to faults in their competitor's processes as
weaknesses of their competitor's product. Specifications would have to address these issues as to