New Reinforced Concrete Design to ACI 318-2019 - US Head Code
In Tekla Structural Designer 2021 ACI 318-2019 is added to the Resistance Codes available for USA Concrete Design. The scope essentially matches that of the existing 2008, 11 and 14 versions for Static and loading, and applies to all the following concrete elements; Reinforced Concrete Beams, Columns and Walls; Reinforced Concrete Slab Panels, Slab Patches and isolated Punching Checks; Reinforced Concrete Spread and Strip Footings, Pile Caps and Mat Foundations. Design for Seismic loading is covered for; Beams, Columns and Walls. There are many detail changes incorporated in the update in accordance with the new code version - for full details of these please see the new Help Topic ACI 318-19 updates and its subtopics. We include just a few highlights and items of note here.
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General:
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Clause 20.2.2.4 of ACI-318-19 makes a revision to reinforcement strength, limiting it to 100 ksi. Accordingly a new 100 ksi reinforcement grade with common bars sizes has been added to the Materials database.
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As per Table 21.2.2 - For tension controlled sections the strain limit is revised from 0.004 to єty + 0.003. This is reflected in updated design calculations wherever required in the calculation of flexure checks.
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Clause 19.2.1.1 has added a minimum compressive strength (fck) check.
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Concrete Column Design - Clause 22.5.5.1 introduces revised shear equations while Clause 22.5.1.10 adds a new biaxial shear check; column design is updated accordingly to these.
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Clause 22.5.5.1 changes - account for size effect and for low longitudinal reinforcement ratios for members without shear reinforcement. The design equations are simplified ( 8 Equations ➝ 3 Equations). The changes of this clause are also reflected in revised sectional shear checks for other entities such as walls, slabs and foundations.
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Clause 15.4 is implemented which adds a joint shear check for static gravity loads, in line with that for seismic design.
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Seismic - the revisions of Clauses 20.2.2.4, and 19.1.1 to reinforcement strength/ yield strength and minimum compressive strength check respectively are also implemented in seismic design for beams, columns and walls as appropriate. Design specific to the entity type is also updated in several areas accordingly:
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Beams - design implements the following clauses; Cl. 18.6.3.1, 18.8.2.3 and 18.6.4.4.
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Columns - design implements the following clauses; Cl. 18.7.3.1, 18.8.4.3, 18.7.5.3, 18.8.3.1, 18.7.5.5 and 18.4.3.3
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Walls - design implements the following clauses; Cl. 20.2.2.4, 19.2.1.1, 18.10.3.1 18.10.6.4(e) and 18.10.6.5
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