The development length of reinforcement is a critical parameter in structural concrete design, ensuring that reinforcing bars can adequately transfer stresses between the concrete and steel. セクション 12.2 そして 12.3 of CSA A23.3-14 provides the requirements and methodologies for calculating development length to achieve proper anchorage of reinforcement. This ensures structural integrity, 安全性, and serviceability under various loading conditions. The development length is influenced by bar size, コンクリートの強度, bond conditions, カバー, 間隔, and whether the bar is in tension or compression. The provision covers basic development lengths for straight bars, adjustments for epoxy coatings, confinement effects, and conditions where bars are hooked or bundled.

The latest SkyCiv Foundation Design update supports standard hooked reinforcements, enabling precise development length checks. Users can now customize footing bar ends as straight bars, 90° hooks, or 180° hooks, ensuring flexibility for various design needs. This guide outlines the step-by-step process for determining the required development length for pad footings following CSA A23.3-14 Section 12, considering relevant modification factors to comply with code requirements.

SkyCivのFoundationDesignソフトウェアを試してみたい? 当社の無料ツールを使用すると、ユーザーは次のことを実行できます。 コンクリート基礎の計算 何もダウンロードしたりインストールしたりせずに!

無料のコンクリート基礎計算機

 

Development Length Check for Dowel Bars

Dowel bars in pad footings ensure a strong connection between the footing and columns, effectively transferring loads and maintaining structural integrity. Factors such as bar diameter, 鋼種, and concrete strength determine the required embedment. Ensure the embedment meets or exceeds the calculated length for safe load transfer and anchorage. 通常, column pedestals are subjected to compression loads, and the required development length is calculated using the provisions under Section 12.3.

 

セクション 12.3.2: Basic compression development length (l_db)

\(l_{db} = MAX \left[ 0.24 \SkyCiv Foundationには、オーストラリア規格に準拠した孤立した基礎の設計が含まれています¹{b} \フラク{ f_{そして} }{\平方根{f’_{c}}}, 0.044 d_{b} f_{そして}, 200mm \right]\) Eq.1どこ:

f_そして = Rebar yield strength (MPa)
f’_c = Concrete strength (MPa)
d_b = Dowel bar diameter (んん)

 

The SkyCiv Foundation Design module checks each load combination to determine if the column is subjected to tensile forces. もしそうなら, the required development length is calculated following Section 12.5.

Available depth (l)

The available depth should be greater than or equal to the calculated required embedment of the dowel bars. This depth is checked using Equations 2, then compared to the computed development length for the utility ratio.

 

\(l = t – (カバー + d_{b,バツ} + d_{b,と}) \) (Eq. 2)

どこ:

t = Footing Thickness (んん)
cover = Bottom concrete cover (んん)
d_b,バツ, d_b,と = Footing bar size in the x and z directions (んん)

 

Development Length Check For Footing Reinforcements

The SkyCiv Foundation Design module allows users to specify bar end configurations as straight or hooked bars (90° or 180°).

 

Calculating the required development length for footing reinforcements directly influences the footing’s dimensions, ensuring they are adequate to anchor the reinforcement against tensile forces. セクション 12.2 そして 12.5 provides a guide on determining the required development length for footing reinforcements.

Straight bars (セクション 12.2.3)

\(l_{d} = MAX \left[ 0.45 \times k1 \times k2 \times k3 \times k4 \times \frac{ f_{そして} } {\平方根{ f’_{c}}}\SkyCiv Foundationには、オーストラリア規格に準拠した孤立した基礎の設計が含まれています¹{b}, 300mm \right]\)(Eq. 3) 

\(l_{d} = MAX \left[ 0.6 \times k1 \times k2 \times k3 \times k4 \times \frac{ f_{そして} } {\平方根{ f’_{c}}}\SkyCiv Foundationには、オーストラリア規格に準拠した孤立した基礎の設計が含まれています¹{b}, 300mm \right]\)(Eq. 4)

どこ:

セクション 12.2.4: Modification factors

Standard hooked bars (セクション 12.5)

\(l_{hb} = frac{100 d_{b}}{\平方根{f’_{c}}} \) (Eq. 5) 

\(l_{dh} = MAX \left[ l_{hb}, 8d_{b}, 150 mm \right]\) (Eq. 6)

The basic development length, l_hb, shall be multiplied by applicable modification factors:

セクション 12.5.3: Factors modifying hook development length

 

Available Development Length

\(l_{提供された} \geq l_{d,req’d}\) (Eq. 7)

 

ディテールチェック: Verification of Footing Thickness (t):

The SkyCiv Foundation Design module checks whether the footing thickness is adequate based on bar configuration and concrete cover. If it is insufficient or the bars protrude, it issues a warning instead of a design failure. The module evaluates the footing thickness at each end of the longitudinal and transverse reinforcements in both the top and bottom layers.

\(\左(\テキスト{h + カバー}\正しい) \leq t\) (Eq. 8)

 

SkyCivのFoundationDesignソフトウェアを試してみたい? 当社の無料ツールを使用すると、ユーザーは次のことを実行できます。 コンクリート基礎の計算 何もダウンロードしたりインストールしたりせずに!

無料のコンクリート基礎計算機