Документация SkyCiv

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  4. CSA A23.3: Руководство по расчету длины разработки

CSA A23.3: Руководство по расчету длины разработки

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. Раздел 12.2 и 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, безопасность, and serviceability under various loading conditions. The development length is influenced by bar size, прочность бетона, bond conditions, крышка, интервал, 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.

Хотите попробовать программное обеспечение SkyCiv Foundation Design? Наш бесплатный инструмент позволяет пользователям выполнять расчеты бетонного фундамента ничего не скачивая и не устанавливая!

 

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, Марка стали, and concrete strength determine the required embedment. Ensure the embedment meets or exceeds the calculated length for safe load transfer and anchorage. типично, column pedestals are subjected to compression loads, and the required development length is calculated using the provisions under Section 12.3.

 

Раздел 12.3.2: Basic compression development length (Ldb)

\(l_{db} = MAX \left[ 0.24 \раз д_{б} \гидроразрыва{ f_{и} }{\SQRT{f'_{с}}}, 0.044 d_{б} f_{и}, 200mm \right]\) Eq.1
куда:

еи = Rebar yield strength (МПа)
е’с = Concrete strength (МПа)
dб = Dowel bar diameter (мм)

 

The SkyCiv Foundation Design module checks each load combination to determine if the column is subjected to tensile forces. Если так, 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.

 

\(l = t – (крышка + d_{б,Икс} + d_{б,с участием}) \) (уравнение. 2)

куда:

t = Footing Thickness (мм)
cover = Bottom concrete cover (мм)
dб,Икс, dб,с участием = Footing bar size in the x and z directions (мм)

 

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. Раздел 12.2 и 12.5 provides a guide on determining the required development length for footing reinforcements.

Straight bars (Раздел 12.2.3)

\(l_{d} = MAX \left[ 0.45 \times k1 \times k2 \times k3 \times k4 \times \frac{ f_{и} } {\SQRT{ f'_{с}}}\раз д_{б}, 300mm \right]\)
(уравнение. 3)
 

\(l_{d} = MAX \left[ 0.6 \times k1 \times k2 \times k3 \times k4 \times \frac{ f_{и} } {\SQRT{ f'_{с}}}\раз д_{б}, 300mm \right]\)
(уравнение. 4)

куда:

Раздел 12.2.4: Modification factors

Standard hooked bars (Раздел 12.5)

\(l_{hb} = frac{100 d_{б}}{\SQRT{f'_{с}}} \) (уравнение. 5)
 

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

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

Раздел 12.5.3: Factors modifying hook development length

 

Available Development Length

The SkyCiv Foundation Design module assesses the anchorage length on both the left and right sides of each column face. Each anchorage length must meet or exceed the greater of the required development length or the minimum extension length.

\(l_{provided} \geq l_{d,req’d}\) (уравнение. 7)

 

Детальная проверка: 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.

\(\осталось(\текст{час + крышка}\право) \leq t\) (уравнение. 8)

 

Хотите попробовать программное обеспечение SkyCiv Foundation Design? Наш бесплатный инструмент позволяет пользователям выполнять расчеты бетонного фундамента ничего не скачивая и не устанавливая!

 

Разработчик продукции Wilross Papaya
Хоуи имеет степень магистра гражданского строительства Сиднейского университета.
Разработчик продукта
Бакалавр наук, MEng (гражданского)
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