Design Settings > Design Warnings

Tekla Structural Designer
2021
Tekla Structural Designer

Design Settings > Design Warnings

Warnings used as guidance during the design of a structure to US seismic provisions are in effect by default. These can be de-activated as found useful from this page.

Design Warnings (AISC/ASC Head code only)

Setting Description

Concrete Seismic Warnings

Specified concrete grade is too low
  • Compliance with ACI 318-08 and ACI 318-11 Section 21.1.4.2, “(..) f’c, shall not be less than 3000 psi.“
  • Applies to normal weight reinforced concrete columns and beams part of Special Moment Frames
  • Applies to normal weight reinforced concrete walls assigned as Special Reinforced Concrete Structural Walls
  • Prompts the designer to increase the concrete grade of the member
Specified longitudinal reinforcement grade too high
  • Compliance with ACI 318-11 Section 21.1.5.2, “(..) reinforcement resisting earth-quake induced flexure, axial force, or both, shall comply with ASTM A706, Grade 60.”
  • Applies to normal weight reinforced columns and beams part of Special Moment Frames
  • Applies to normal weight reinforced concrete walls assigned as Special Reinforced Concrete Structural Walls
  • Prompts the designer to use lower longitudinal reinforcement grades
Column at the end of the beam is not in the same seismic frame
  • Used to validate if the frame of which the beam is part of is correctly set-up as a seismic frame
  • Applies to normal weight reinforced concrete beams part of a seismic force resisting system
  • Applies to both SRFS type and direction
  • Checks both ends of each beam span
  • Prompts the designer to set up a consistent SFRS type and direction between all members of the frame
Beam at the end of the column is not in the same seismic frame
  • Used to validate if the frame of which the column is part off is correctly set-up as a seismic frame
  • Applies to normal weight reinforced concrete columns part of a seismic force resisting system
  • Checks the top of each column stack
  • Prompts the designer to set up a consistent SFRS type and direction between all members of the frame
Beam support region size is too small
  • Compliance with ACI 318-08 and ACI 318-11 Section 21.3.4.2, “(..) hoops shall be provided over lengths not less than 2h measured from the face of the supported member toward the midspan”
  • Applies to normal weight reinforced concrete beams part of Intermediate and Special Moment Frames
  • Comes into effect if the length of the end shear design regions is smaller than the requirement
  • Prompts the designer to review the shear design regions - Design options

High seismic to conventional demand on non-SFRS beams

High seismic to conventional demand ratio of non-SFRS columns

High seismic to conventional demand of non-SFRS walls

  • Used to recognize when a member has a significant contribution to the building’s lateral force resistance but has not been assigned to the SFRS with the required ductility properties
  • Specifically apply to each member type
  • The highest non-seismic design ratio from bending and shear design is obtained
  • The highest seismic design ratio from bending and shear design is obtained
  • Comes into effect when the ratio between seismic and non-seismic values is higher than a given threshold (default = 1.0)
  • The maximum seismic/non-seismic ratio threshold that triggers the warning is set through the Seismic to conventional minimum demand ratio field described below
  • Prompts the designer to either include the member in the SFRS or review the structure layout to reduce the contribution of the member to the lateral force resistance
Non-SFRS design requirements applicable in SDC D-F
  • Compliance with ACI 318-08 and ACI 318-11 Sections 21.13.1, “Requirements of section 21.13 apply to members not designated as part of the seismic-force-resisting system in structures assigned to SDC D, E and F”
  • Applies to normal weight reinforced concrete beams, column and walls not included in the SFRS
  • Comes into effect in Seismic Design Category, SDC D or above
  • Prompts the designer to apply code prescribed requirements on top of current design
Steel Static Warnings

Additional notional loads required when alpha Pr/Py > 0.5, C2.3

  • Compliance with 7.3 (3) of AISC 360-05 and C2.3 of AISC 360-10 requires the stiffness of certain members to be reduced. When the ratio of the required axial compressive force (Pr) and the axial yield strength (Py = Fy Ag) is > 0.5 then this stiffness must be reduced further
  • As an alternative which is the approach adopted in Tekla Structural Designer, an additional notional load of 0.001 Yi can be applied instead
  • When the program identifies that the ratio of Pr/Py exceeds 0.5 a warning is given to alert the designer
  • If this additional notional load has been dealt with by the designer then this warning is no longer relevant and this option allows you to switch off the warning
Concrete Seismic

Seismic to conventional minimum demand ratio

  • Sets the maximum seismic/non-seismic ratio threshold, which is used to trigger the High seismic to conventional demandwarnings listed above
  • Default: 1.000
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