Limitations and assumptions (walls seismic: ACI 318)
The following limitations and assumptions apply.
- For design purposes Tekla Structural Designer recognizes walls as isolated elements and as such the influence of flanges from adjacent walls are not to be considered when fulfilling seismic design requirements in those elements. Requirements of ACI318-11 section 21.9.5.2 and section 21.9.6.4(b) do not apply.
- Additional requirements for wall piers not part of any SFRS when in Seismic Design Categories D through F are not considered in the current release.
- Design and/or detailing requirements of Special Reinforced Concrete Structural Walls is beyond scope (some checks are implemented but only due to their existence in lower toughness systems).
- The use of spiral reinforcement as well as all seismic design checks and related assumptions are not considered due to the fact that this type of reinforcement is not currently available in Tekla Structural Designer.
- Special boundary elements in walls are directly linked with wall end-zones in Tekla Structural Designer. The current settings do not allow for end-zones of width different from the width of the wall itself.
- The Seismic Force Resisting System set by the user in each direction through the Seismic Wizard for analysis purposes is not checked for applicability against the allowed types from the resultant Seismic Design Category. This is user responsibility.
- Seismic design checks are mostly based on capacity design obtained from the main reinforcement provided. This can lead to an over-design of structural members if the designer is not careful enough to minimize excess capacity.
- The seismic design requirements for end-zone reinforcement are beyond scope in the current release.
- Construction joints are beyond scope in the current release.
- Seismic design provisions specific for beam-wall frames are beyond scope in the current release.
- Seismic design of walls with openings is beyond scope in the current release.
- Seismic design of wall piers is beyond scope in the current release.
- Seismic design of coupling beams is beyond scope in the current release.
- Seismic detailing requirements apply to Special Reinforced Concrete Structural Walls these are beyond scope in the current release.
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Note: A full list of the code checks that have and have not been implemented is provided in the table below.
ACI 318 Seismic Code Checks for walls that have been implemented in Tekla Structural Designer
| Code Ref. | Requirement | SFRS | SDC A | SDC B | SDC C | SDC D,E,F |
|---|---|---|---|---|---|---|
| 21.1.4.2 | Minimum required compressive strength of concrete | SRCSW | - | - | - |  |
| 21.1.4.3 | Maximum allowed compressive strength of light-weight concrete | SRCSW | - | - | - | |
| 21.1.5.2 | Maximum allowed steel characteristic yield strength of longitudinal reinforcement | SRCSW | - | - | - | |
| 21.1.5.4 | Maximum yield strength of transverse reinforcement in confinement regions of columns | SRCSW | - | - | - |  |
| 21.1.5.5 | Maximum allowed longitudinal reinforcement yield strength used in the calculation of transverse reinforcement | SRCSW | - | - | - | |
| 21.1.6.1a) | Mechanical Splices outside twice the member depth from column/beam face or yielding regions | SRCSW | - | - | - | |
| 21.1.6.1b) | Mechanical Splices within twice the member depth from column/beam face or yielding regions | SRCSW | - | - | - | |
| 21.1.7.1 | Welded Splices within twice the member depth from column/beam face or yielding regions | SRCSW | - | - | - | |
| 21.1.7.2 | Welding of stirrups or other elements to longitudinal reinf. required by design | SRCSW | - | - | - | |
| 21.12.2.3 | Confinement reinf.: Length inside footing when Special Boundary Element is within half the foundation depth from the footing edge | SRCSW | - | - | - | |
| 21.4.3 | Minimum yield strength of connection not designed to yield | IPCSW | - | - | |
- |
| 21.4.4/21.9.8 | Design of wall piers as columns (lw/bw ≤ 2.5) | SRCSW | - | - | - | |
| 21.9.2.1 | Minimum reinforcement ratio in each of the wall plane orthogonal directions | SRCSW | - | - | - | |
| 21.9.2.1 | Maximum allowed center spacing | SRCSW | - | - | - | |
| 21.9.2.2 | Minimum number of reinforcement layers | SRCSW | - | - | - | |
| 21.9.2.3a) | Minimum discontinuous vertical bar extension | SRCSW | - | - | - | |
| 21.9.2.3a) | Development length at locations where flexural yielding is likely to occur | SRCSW | - | - | - | |
| 21.9.2.3c) | Minimum yield strength for development length and lap splices | SRCSW | - | - | - | |
| 21.9.3 | Factored shear force at any section from lateral load analysis | SRCSW | - | - | - | |
| 21.9.4.1 | Maximum nominal shear strength | SRCSW | - | - | - | |
| 21.9.4.3 | Reinforcement in wall plane provided in both directions | SRCSW | - | - | - | |
| 21.9.4.3 | Minimum in plane reinforcement ratios | SRCSW | - | - | - | |
| 21.9.4.4 | Maximum wall segment combined nominal shear strength | SRCSW | - | - | - | |
| 21.9.4.4/21.9.4.5 | Maximum individual vertical or horizontal wall segment or coupling beam shear strength | SRCSW | - | - | - | |
| 21.9.5.2 | Effective width of flanged wall sections | SRCSW | - | - | - | |
| 21.9.6.3 | Minimum extreme fiber compressive stress to require Special Boundary Elements | SRCSW | - | - | - | |
| 21.9.6.3 | Minimum stress to discontinue Special Boundary Element | SRCSW | - | - | - | |
| 21.9.6.4(a) | Minimum length of end-zone towards the center of the cross-section when Special Boundary Elements are required | SRCSW | - | - | - | |
| 21.9.6.4(b) | Minimum length of end-zone towards the center of the cross-section in flanged sections with Special Boundary Elements | SRCSW | - | - | - | |
| - | Minimum width of end-zone with special boundary elements | SRCSW | - | - | - | |
| 21.9.6.4(c) | Special confining reinforcement type (hook/extension) | SRCSW | - | - | - | |
| 21.9.6.4c) | Confining reinf.: Maximum spacing allowed between cross ties | SRCSW | - | - | - | |
| 21.9.6.4c) | Confining reinf.: Maximum allowed longitudinal center link spacing | SRCSW | - | - | - | |
| 21.9.6.4c) | Confinement reinf.: Minimum volumetric ratio / area of spiral or circular reinforcement | SRCSW | - | - | - | |
| 21.9.6.4c) | Confinement Reinf.: Minimum area of rectangular transverse reinforcement | SRCSW | - | - | - | |
| 21.9.6.4d) | Confining reinf.: Length of region inside footings, mats or pile caps, ld | SRCSW | - | - | - | |
| 21.9.6.4d) | Confining reinf.: Length of region into support | SRCSW | - | - | - | |
| 21.9.6.4e) | Development / anchorage of horizontal reinforcement with boundary elements | SRCSW | - | - | - | |
| 21.9.6.5a) | Ordinary Boundary Confinement region length - towards the center of the cross-section - at an end where special boundary elements are not required | SRCSW | - | - | - | |
| 21.9.6.5a) | Maximum spacing allowed between cross ties in high compression confinement reinf. at a boundary where special boundary elements are not required | SRCSW | - | - | - | |
| 21.9.6.5a) | Maximum long. center spacing of high compression confinement reinforcement at an end where special boundary elements are not required | SRCSW | - | - | - | |
| 21.9.6.5a) | Maximum spacing allowed between cross ties or legs of hoops | SRCSW | - | - | - | |
| 21.9.6.5b) | Design shear threshold for ignoring the need of engaging horizontal bars at the ends with standard hooks | SRCSW | - | - | - | |
| 21.9.7.1 | Minimum value of aspect ratio (ln/h) to consider diagonal reinf. | SRCSW | - | - | - | |
| 21.9.7.2 | Maximum shear allowed before considering diagonal reinf. | SRCSW | - | - | - | |
| 21.9.7.4a) | Nominal Shear Strength of a coupling beam | SRCSW | - | - | - | |
| 21.9.7.4b) | Minimum number of bars to be provided along each diagonal | SRCSW | - | - | - | |
| 21.9.7.4b) | Minimum length of diagonal bars embedded into the wall | SRCSW | - | - | - | |
| 21.9.7.4c) | Minimum breadth of the concrete core measured to the external face of the confining reinforcement | SRCSW | - | - | - | |
| 21.9.7.4c) | Minimum dimension of the concrete core in any direction than not the parallel to bw, measured to the external face of the confining reinf. | SRCSW | - | - | - | |
| 21.9.7.4c) | Special confining reinforcement (hook/extension) | SRCSW | - | - | - | |
| 21.9.7.4c) | Confining reinf.: Maximum allowed center link spacing | SRCSW | - | - | - | |
| 21.9.7.4c) | Confining reinf.: Minimum volumetric ratio / area of spiral or circular reinf. | SRCSW | - | - | - | |
| 21.9.7.4c) | Confining Reinf.: Minimum area of rectangular transverse reinf. | SRCSW | - | - | - | |
| 21.9.7.4c) | Minimum allowed total area of the additional longitudinal reinforcement | SRCSW | - | - | - | |
| 21.9.7.4c) | Maximum allowed spacing between the additional longitudinal bars | SRCSW | - | - | - | |
| 21.9.7.4c) | Minimum allowed area of the additional transverse reinforcement | SRCSW | - | - | - | |
| 21.9.7.4c) | Maximum allowed spacing between the additional transverse bars | SRCSW | - | - | - | |
| 21.9.8.1a) | Design shear force calculation for wall piers with lw/bw > 2.5 and not designed as columns | SRCSW | - | - | - | |
| 21.9.8.1b) | Nominal shear strength and distributed shear reinforcement | SRCSW | - | - | - | |
| 21.9.8.1c) | Reinforcement type requirement for wall piers with lw/bw > 2.5 and not designed as columns | SRCSW | - | - | - | |
| 21.9.8.1d) |
Maximum allowed vertical spacing of transverse reinforcement. Wall piers with lw/bw > 2.5 and not designed as columns |
SRCSW | - | - | - | |
| 21.9.8.1e) | Length of the transverse reinf. region above and below the wall pier. Wall piers with lw/bw > 2.5 and not designed as columns | SRCSW | - | - | - | |
| 21.9.8.1f) | Consider boundary elements | SRCSW | - | - | - | |
| 21.9.8.2 | Horizontal reinf. In adjacent walls when wall pier is at the edge of a wall | SRCSW | - | - | - | |
| ASCE 7/10 - 12.2.1 | Limiting Height | SRCSW | - | - | - | |
| ASCE 7/10 - 12.2.1 | Limiting Height | IPCSW | - | - | - | |
| R21.9.1 | Vertical Segment Classification: Conditions for wall segments to require specific wall pier design | SRCSW | - | - | - | |
Note:
- For further details of the checks that have been implemented, see: General requirements (walls seismic: ACI 318), or consult the respective clause reference in the code.
- Most of the requirements will be fulfilled through automatic design. In some cases specific design options will need to be set by the user.
- Additional requirements may apply to members that are not part of the SFRS when in SDC’s D, E or F
- Confinement regions: - support regions; - Probable flexural yield regions; - Lap splice regions.