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.