> For the complete documentation index, see [llms.txt](https://docs.enercalc.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.enercalc.com/sel-faq/using-the-software/calculation-modules/columns/deflection-in-masonry-columns.md).

# Deflection in Masonry Columns

Why the Masonry Column module reports deflections using gross rather than cracked section properties.

## Why does the Masonry Column module report deflections calculated using gross section properties (rather than cracked section properties)?

Short answer: **TMS 402-22 does** ***not*** **explicitly require using cracked-section properties for deflection of reinforced masonry columns; it is largely silent on a detailed cracked vs. gross stiffness model for column deflection.** In practice, the code framework implies **elastic (uncracked / effective) stiffness unless second-order analysis or rational methods justify otherwise**, with additional guidance coming from commentary and general masonry design practice rather than a prescriptive clause.

**What TMS 402-22 actually provides**

TMS 402 is written as a **minimum design code covering strength and serviceability**, but it intentionally avoids prescribing detailed analysis models for stiffness in many cases ([Accuris Standards Store](https://store.accuristech.com/mss/products/preview/2505452?utm_source=chatgpt.com)).

For columns specifically:

* The code addresses **axial load, flexure, and slenderness (P–Δ effects)**.
* It requires accounting for **second-order effects** when slenderness is significant.
* It relies on **modulus of elasticity (Em)**–based stiffness in analysis.

However:

* There is **no explicit clause stating “use cracked section properties”** for deflection of masonry columns.
* Nor is there a direct requirement to use gross section properties.

**Implied stiffness model in TMS 402**

From how the code is structured:

**1. Elastic stiffness basis**

* Masonry analysis in TMS 402 is fundamentally **elastic-based (Em·I)** for service-level behavior.
* Section properties used for stiffness are typically **gross or effective (uncracked) section properties** unless a refined analysis is performed.

This aligns with general masonry guidance:

* **Average (uncracked) section properties → used for elastic stiffness**
* **Cracked/effective properties → used only when explicitly modeling inelastic response or for refined deflection estimates** ([CMHA](https://www.cmha.org/resource/cmu-tec-002/?utm_source=chatgpt.com))

**2. Second-order (slenderness) effects**

* For columns, deflection is primarily handled indirectly through:
  * **moment magnification** or
  * **second-order analysis**
* These provisions are based on **member stiffness (EI)**, but again the code does not redefine I as cracked.

**Commentary / engineering interpretation**

The **TMS 402-22 Commentary (non-mandatory)** is where intent is clarified:

* Masonry is **brittle in tension**, so cracking can occur.
* However, for columns under **dominant axial compression**, flexural cracking is often limited.
* Therefore, **gross or effective section properties are typically acceptable for column stiffness**, especially for:
  * compression-controlled sections
  * members with low tension demand

Cracked-section modeling is generally:

* **not required by code**, and
* only used when performing **advanced analysis or when flexural tension governs**.

**Practical design takeaway**

For reinforced concrete masonry columns under TMS 402-22:

* **Default / code-consistent approach**
  * Use **gross (or effective uncracked) section properties** for stiffness (EI)
  * Apply **slenderness / second-order provisions** as required
* **When cracked properties may be used (engineering judgment)**
  * Significant bending with tensile cracking
  * Detailed deflection predictions (serviceability-critical elements)
  * Nonlinear or refined analysis
* **What the code does NOT do**
  * It does **not mandate cracked inertia (Icr)** like ACI 318 does for RC beams/columns in deflection checks.

**Bottom line**

**TMS 402-22 does not explicitly require cracked section properties for deflection of reinforced masonry columns.**

The code framework implies use of **gross (elastic) section stiffness**, with cracked-section analysis being optional and based on engineering judgment rather than a prescriptive requirement.


---

# Agent Instructions
This documentation is published with GitBook. GitBook is the documentation platform designed so that both humans and AI agents can read, navigate, and reason over technical content effectively. Learn more at gitbook.com.

## Querying This Documentation
If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question.

Perform an HTTP GET request on the current page URL with the `ask` query parameter, and the optional `goal` query parameter:

```
GET https://docs.enercalc.com/sel-faq/using-the-software/calculation-modules/columns/deflection-in-masonry-columns.md?ask=<question>&goal=<endgoal>
```

`ask` is the immediate question: it should be specific, self-contained, and written in natural language.
`goal` is optional and describes the broader end goal you are ultimately trying to accomplish on behalf of the user. GitBook uses it to tailor the answer towards what is most useful for that goal.

The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.

Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.