> For the complete documentation index, see [llms.txt](https://docs.openbrim.org/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.openbrim.org/templates/concrete-box-girder-bridge-workflow/templates-for-code-check-and-load-rating-cbg/concrete-box-girder-code-check-template-t-cbg.md). # Concrete Box Girder Code Check Template \[CBG] This template gathers the AASHTO design parameters used by every Concrete Box Girder Code Check object in the project. Create one template per code edition / project setting and point all girder code check objects at it; that way edits to factors, loss methods or section-analysis settings propagate to every check at once. ### General **Load Combination Table:** Pick the load combination table that drives all factored demands (Strength I, Service I, Service III, Fatigue, Extreme Event). Per AASHTO 5.5.3 and 3.4.1 the Service III live-load factor depends on structure type — γ\_LL = 0.8 for segmental and bonded post-tensioned bridges, γ\_LL = 1.0 for typical pretensioned girders — so make sure the table you choose uses the value appropriate for the structure being checked. Required. **PS Load Case:** Pick the analysis case that holds the prestressing (PS) results used as a load source by the code check. ### Design Parameters **Resistance factor Tension Controlled Section (AASHTO Table 5.5.4.2-1):** Φ\_f for tension-controlled sections. Default 1.0. **Resistance factor Compression Controlled Section:** Φ\_f for compression-controlled sections. Default 0.75. **Resistance factor Shear and Torsion in Section:** Φ\_v for shear and torsion. Default 0.9. **Procedure for Shear Parameters β and θ \[Simplified/General(Eqn)/AppendixB5(Table)]:** Method used to evaluate the shear parameters β and θ. Simplified uses the constant values of AASHTO 5.7.3.4.1; General(Eqn) uses the closed-form equations of 5.7.3.4.2; AppendixB5(Table) uses the tabulated values from Appendix B5. **Flexure Sign (Effective Shear Depth) \[Use Critical Shear Concurrent Bending Moment/Use Positive Flexure/Use Negative Flexure/Use Pos and Neg Flexure]:** Which flexural action is paired with the shear demand when computing the effective shear depth d\_v. The default uses the bending moment concurrent with the critical shear; the other options force a positive-only, negative-only or both-sense pairing. **γ3 Rebar Type for Min Reinforcement (AASHTO 5.6.3.3-1) \[Prestressing only γ3 1.0 / A615 Grade 60 γ3 0.67 / A706 Grade 60 γ3 0.75]:** Selects the γ3 ratio used in the minimum-reinforcement check (M\_cr) per AASHTO 5.6.3.3-1, depending on the rebar grade providing the tensile resistance. ### Pretensioning **Time-Dependent Losses Calc. Method \[Approximate/Refined]:** AASHTO method used to compute the long-term (time-dependent) losses for pretensioning strands. Approximate uses the lump-sum equation of AASHTO 5.9.3.3; Refined uses the staged formulation of 5.9.3.4 along the construction stages. **Humidity (%) (Approximate Method):** Ambient relative humidity used by the Approximate loss method. Visible only when the Approximate method is selected. **Compression Check (Approximate Method) \[0.65 fci / 0.45 fc / 0.6 fc]:** Compressive concrete stress limit used in the Approximate-method service stress checks. Visible only with the Approximate method. **Tensile Stress Limit (Approximate Method) \[0.0948λ√fci / 0.24λ√fci / 0.158λ√fci / 0.19λ√fci / No Tension before Losses / 0.19λ√fc / 0.0948λ√fc / No Tension after Losses]:** Tensile concrete stress limit used in the Approximate-method service stress checks. Pick the AASHTO option that matches the exposure / staging condition. Visible only with the Approximate method. ### Post-Tensioning **Time-Dependent Losses Calc. Method \[FEA Results/Refined]:** How long-term losses for post-tensioned tendons are obtained. FEA Results extracts losses from the staged FEA tendon-force history; Refined uses the AASHTO 5.9.3.4 hand calculation (K\_id, K\_df, ψ\_b, etc.). AASHTO does not define a closed-form approximate (lump-sum) method for PT, so there is no Approximate option here. **Post-Tensioning Duct Type \[Ungrouted/Grouted]:** Duct condition assumed by the shear check. Grouted ducts contribute their concrete-equivalent area to b\_v; ungrouted ducts trigger the b\_v reduction below per AASHTO 5.7.2.8. **Total number of PT ducts in webs within depth dv (sum across all webs):** Total count of post-tensioning ducts crossing the web within the effective shear depth d\_v, summed over all webs of the section. Used in the AASHTO 5.7.2.8 b\_v reduction. Visible only when ducts are ungrouted. **Diameter of PT duct in web (for b\_v reduction per AASHTO 5.7.2.8):** Diameter of a single PT duct in the web, used in the b\_v reduction. Visible only when ducts are ungrouted. ### Section Analysis **Ignore Rebar and Tendon in Section Property Calc. \[No/Yes]:** Whether transformed section properties used downstream are computed on the gross concrete section only (Yes) or including the rebar and tendon contributions (No). **Section Analysis Refinement (Total Fiber Count):** Number of fibers used to discretise the section for the moment-curvature / capacity calculation. Higher values give smoother results at the cost of compute time. Default 200. **Use Tendons in Section Capacity Calculation \[Yes/No]:** Whether bonded tendons are included in the M\_n / V\_n capacity calculation. Set No when the project requires capacity to be checked against rebar only. ### Report **Support Lines Used For Span Length Comp. \[All/Selection]:** How span lengths are determined for the report tables. All uses every support line bounding the girder; Selection uses only the support lines listed below. **Selected Support Lines:** Pick the support lines whose stations define the spans for reporting. Used only when the support-line method is set to Selection. --- # Agent Instructions This documentation is published with GitBook. GitBook is the documentation platform designed so that both humans and AI agents can read, navigate, and reason over technical content effectively. Learn more at gitbook.com. ## Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question. Perform an HTTP GET request on the current page URL with the `ask` query parameter, and the optional `goal` query parameter: ``` GET https://docs.openbrim.org/templates/concrete-box-girder-bridge-workflow/templates-for-code-check-and-load-rating-cbg/concrete-box-girder-code-check-template-t-cbg.md?ask=&goal= ``` `ask` is the immediate question: it should be specific, self-contained, and written in natural language. `goal` is optional and describes the broader end goal you are ultimately trying to accomplish on behalf of the user. GitBook uses it to tailor the answer towards what is most useful for that goal. The response will contain a direct answer to the question and relevant excerpts and sources from the documentation. Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.