# 11.8 Alternative Method for Out-Of-Plane Slender Wall Analysis

(a) Cross section is constant over the height of the wall

(b) Wall is tension-controlled for out-of-plane moment effect

(c) **ϕ M_{n}** is at least

**, where**

*M*_{cr}**is calculated using**

*M*_{cr}**as provided in 19.2.3**

*f*_{r}(d) ** P_{u}** at the midheight section does not exceed

**0.06**

*f'*_{c}*A*_{g}(e) Calculated out-of-plane deflection due to service loads, **Δ _{s}**, including

**effects, does not exceed**

*P*Δ

*ℓ*/150_{c}(a) The spacing of the concentrated loads

(b) The edges of the wall panel

*M*at midheight of wall due to combined flexure and axial loads shall include the effects of wall deflection in accordance with (a) or (b):

_{u}(a) By iterative calculation using

M = _{u}M+ _{ua}PΔ_{u}_{u} | (11.8.3.1a) |

where ** M_{ua}** is the maximum factored moment at midheight of wall due to lateral and eccentric vertical loads, not including

**effects.**

*P*Δ**Δ _{u}** shall be calculated by:

(11.8.3.1b) |

where ** I_{cr}** shall be calculated by:

(11.8.3.1c) |

and the value of ** E_{s}/E_{c}** shall be at least 6.

(b) By direct calculation using:

(11.8.3.1d) |

**Δ**, shall be calculated in accordance with Table 11.8.4.1, where

_{s}**is calculated by 11.8.4.2.**

*M*_{a}**Table 11.8.4.1—Calculation of** Δ_{s}

M_{a} | Δ_{s} | |
---|---|---|

≤ (2/3)M_{cr} | (a) | |

> (2/3)M_{cr} | (b) |

_{cr}and

**Δ**shall be calculated by (a) and (b):

_{n}(a) | (11.8.4.3a) |

(b) | (11.8.4.3b) |

*I*shall be calculated by Eq. (11.8.3.1c).

_{cr}### Related Code Sections

*out*-of-

*plane*

*slenderness*effects in accordance with this section for

*walls*satisfying (a) through (e): (a) Cross ...

*wall*shall be analyzed as a simply supported, axially loaded member subject to an

*out*-of-

*plane*uniformly distributed lateral load, with maximum ...

*Modeling*> 11.8.2.1

*wall*above any section shall be assumed to be distributed over a width equal to the bearing width, plus ...

*Modeling*> 11.8.2.2

*wall*due to combined flexure and axial loads shall include the effects of

*wall*deflection in accordance with (a) or (b ...

*Factored Moment*> 11.8.3.1

*Out*-of-

*plane*deflection due to service loads, Δ s , shall be calculated in accordance with Table 11.8.4.1, where M a is calculated ...

*Out-Of-Plane Deflection — Service Loads*> 11.8.4.1