Critical section tables are shown in multiple places throughout the Eriksson Culvert text report:
The “Critical Section Summary” is near the top of the report and shows the controlling critical section for each location.
The “Strength Limit State at Critical Sections” tables are displayed for each truck/fill depth combination in the analysis. These tables provide design information at each critical section for the particular truck/fill depth analysis.
Now we will discuss each column in the flexural critical section tables:
Loc: This column gives a description of the location of the critical section. For box culverts, the following critical sections are analyzed:
For walls: Bottom, Middle+ (positive moment), Middle- (negative moment), and Top
For slabs: Left, Middle, and Right
Dist: The distance column displays the location of the critical section, measured in inches, from the centerline of the intersecting member (or from the corresponding node in the FEM analysis). For instance, in the above screenshot, the exterior wall bottom critical section is located at 8.5”. This means it is 8.5” up from the centerline of the bottom slab. Additionally, the exterior wall top critical section is located at 9.0”, which is 9.0” down from the centerline of the top slab.
Design Moment: The factored moment being applied at the critical section location.
Corr. A.F: The corresponding axial force given by the same load combination that produced the design moment.
Mu: The capacity of the section, not taking axial force into account.
ds: Depth to the flexural steel.
Ma: The capacity of the section, considering axial forces.
As: Area of flexural steel.
Mcr: Cracking moment.
IR: Inventory load rating.
OR: Operating load rating.
Truck: The truck from the corresponding truck/fill depth combination that produced this load case. (Only shown in the Critical Section Summary)
Fill Depth: The fill depth from the corresponding truck/fill depth combination that produced this load case. (Only shown in the Critical Section Summary)
Now we will discuss each column in the shear critical section tables:
Loc: This column gives a description of the location of the critical section. For box culverts, the following critical sections are analyzed:
For walls: Bottom, Middle+ (positive moment), Middle- (negative moment), and Top
For slabs: Left, Middle, and Right
Dist: The distance column displays the location of the critical section, measured in inches, from the centerline of the intersecting member (or from the corresponding node in the FEM analysis). For instance, in the above screenshot, the exterior wall bottom critical section is located at 8.5”. This means it is 8.5” up from the centerline of the bottom slab. Additionally, the exterior wall top critical section is located at 9.0”, which is 9.0” down from the centerline of the top slab.
Design Shear: The factored moment being applied at the critical section location.
Corr. Moment: The corresponding moment given by the same load combination that produced the design shear.
Corr. A.F: The corresponding axial force given by the same load combination that produced the design moment.
Dv: Depth to the flexural steel.
Vc: Shear capacity of the concrete section.
Vs: Shear capacity of the added shear steel.
Av: Area of shear steel.
Max Spacing: Maximum spacing of the shear reinforcement.
IR: Inventory load rating.
OR: Operating load rating.
Truck: The truck from the corresponding truck/fill depth combination that produced this load case. (Only shown in the Critical Section Summary)
Fill Depth: The fill depth from the corresponding truck/fill depth combination that produced this load case. (Only shown in the Critical Section Summary)