# Longitudinal Reinforcement (SwRD)

Longitudinal reinforcement detailing is applied automatically in accordance with

**ACI 11.7**

Longitudinal reinforcement detailing is applied according to

**ACI Chapter 18**in special structural walls.

**Notation**

* A_{g }= *gross area of concrete section, in

^{2}

**A**_{st }**=**total area of nonprestressed longitudinal reinforcement, in

^{2}

*web width or diameter of circular section, in.*

**b**_{w }=*distance from extreme compression fiber to centroid of longitudinal tension reinforcement, in.*

**d =**

**d**_{b }**=**nominal diameter of bar, wire, or prestressing strand, in

**√f**_{c}‘*square root of specified compressive strength of concrete, psi*

**=**

**f**_{y}**=**specified yield strength of nonprestressed reinforcement,

**psi**

*specified yield strength of transverse reinforcement, psi*

**f**_{yt }=

**h**

**=**overall thickness, height, or depth of member, in.

**h**_{sx}**=**story height for story x, in.

**h**_{w}**=**height of entire wall from base to top, or clear height of wall segment or wall pier considered, in.

**l****development length in tension of deformed bar, deformed wire, plain and deformed welded wire reinforcement, or pretensioned strand, in.**

_{d}=

**l**_{w }**=**length of entire wall, or length of wall segment or wall pier considered in direction of shear force, in.

**M**_{u}**factored moment at section, in.-lb**

_{ }=

**s****=**center-to-center spacing of items, such as longitudinal reinforcement, transverse reinforcement, tendons, or anchors, in.

*factored shear force at section, lb*

**V**_{u }=*strength reduction factor*

**ϕ =**According to **ACI 11.7.2.1**; maximum spacing of longitudinal reinforcement bars in shear walls is the lesser of * 3h *and 18 inches. If shear reinforcement is required for in-plane strength, maximum longitunal reinforcement spacing is

**l**_{w}/3.According to **ACI 11.7.4.1**; logitudinal reinforcement should be laterally supported bu transverse reinforcement if the following two conditions are satified;

**A**_{st}> 0.01A_{g}longitudinal reinforcement is required

**Earthquake Reistant Structures**

**Special structural walls**

According to **ACI 18.10.2.3**; longitudinal reinforcement in structural walls should be satisfied the requirements in titles Development of Reinforcement and Splices as well as the following conditions;

Except at the top of a wall, longitudinal reinforcement shall extend at least 12 ft above the point at which it is no longer required to resist flexure but need not extend more than

**l**above the next floor level._{d}At locations where longitudinal reinforcement yielding is likely to occur due to lateral displacements , development lengths of longitudinal reinforcement should be 1.25 times the values calculated for

in tension.**f**_{y}At locations where yielding of longitudinal reinforcement is likely to occur due to lateral displacements, lap splices of longitudinal reinforcement within boundary regions should not be permitted over a height equal to

above, and**h**_{sx}**l**below. The maximum value of_{d}is 20 ft.**h**_{sx}

According to **ACI 18.10.2.4**; walls or wall piers with **h _{w}/l_{w}**

*that are effectively continuous from the base of structure to top of wall and are designed to have a single critical section for flexure and axial loads should have longitudinal reinforcement at the ends of a vertical wall segment that satisfies conditions given below;*

**≥ 2.0**minimum longitudinal reinforcement ratio in the area

from the end of a vertical wall segment, and over a width equal to the wall thickness, should be**0.15l**_{w}.**6√f**_{c}‘/f_{y}longitudinal reinforcement should extend vertically above and below the critical section at least the greater of

and**l**_{w}**M**_{u}/3V_{u.}no more 50 percent of the longitudinal reinforcement should be terminated at any one section.

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