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STM design provisions consist of rules for defining the dimensions and ultimate stress limits of struts and nodes as well as the requirements for the distribution and anchorage of reinforcement. Guidelines
[5, 6] for design by the STM have been developed for European practice.
Provisions for the STM have been incorporated in the Canadian Concrete Design Code [7, 8]
since 1984 and in the AASHTO LRFD [9, 10] code
since 1994. Another specific set of provisions has been developed to be included as an alternative design procedure in the 2002 ACI
code [11].
Table 1
and Table 2 show examples of stress limits and
strength reduction factors defined in ACI Code and AASHTO LRFD Bridge Design Specifications, respectively.
As shown in the tables, there are substantial differences in the rules used in these provisions and
guidelines because of uncertainties associated with defining the characteristics of an idealized truss within a continuum of structural concrete.
Table 1 Stress Limits and Strength Reduction Factors According to ACI 318-02 Appendix
A [11]
Table 2 Stress Limits and Strength Reduction Factors According to AASHTO LRFD Bridge Design Specifications 2nd Edition [10]
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for prismatic struts in uncracked compression zones
for struts in tension members
struts may be bottle shaped and crack control reinforcement is included
struts may be bottle shaped and crack control reinforcement is not included
specified concrete compressive strength
, where 
= steel ratio of the i-th layer of reinforcement crossing the strut under review, and 
= angle between the axis of the strut and the bars.
when nodes are bounded by struts and/or bearing areas
when nodes anchor only one tie
when nodes anchor more than one tie
for struts, ties, and nodes
=
= smallest angle between the strut under review and the adjoining ties
= average tensile strain in the tie direction
= specified concrete compressive strength
when nodes are bounded by struts and/or bearing areas
when nodes anchor only one tie
when nodes anchor more than one tie
for struts and nodes
for ties