Building Design and Construction Handbook - Merritt - Ventech!

9.62
TABLE 9.8 Tension Development Lengths, L d, for Grade 60 Uncoated Bars (Inches)
Bar
size no.
Top bars
ƒ� c
Case 1 Case 2
� 3,000 psi
Other bars
Case 1 Case 2
Top bars
ƒ� c
Case 1 Case 2
� 4,000 psi
Other bars
Case 1 Case 2
Top bars
ƒ� c
Case 1 Case 2
� 5,000 psi
Other bars
Case 1 Case 2
3 22 32 17 25 19 28 15 22 17 25 13 19
4 29 43 22 33 25 37 19 29 22 33 17 26
5 36 54 28 41 31 47 24 36 28 42 22 32
6 43 64 33 50 37 56 29 43 33 50 26 38
7 63 94 48 72 54 81 42 63 49 73 37 56
8 72 107 55 82 62* 93 48 71 55 83 43 64
9 81 121 62 93 70 105 54 81 63 94 48 72
10 91 136 70 105 79 118 61 91 70 105 54 81
11 101 151 78 116 87 131 67 101 78 117 60 90
14 121 181 93 139 105 157 81 121 94 140 72 108
18 161 241 124 186 139 209 107 161 125 187 96 144
NOTES:
1. Values are based on Section 12.2.2 in ACI 318-99 Building Code.
2. Case 1 and Case 2 are defined:
Structural element
Case
Beams and columns Other elements
1 Concrete cover �db, c.-c. bar
spacing �2 db and with stirrups
or ties throughout Ld not less than
Code minimum
Concrete over �db, c.-c. bar
spacing �3 db 2 Concrete cover �db or c.-c. bar
spacing �2 db Concrete cover �db or c.-c.
bar spacing �3 db 3. Values are for normal-weight concrete.
4. Standard 90� or 180� end hooks may be used to replace part of the required development length. See Table 9.9.
* Sample Calculation: For Case 1, bar size no. 8; using Eq. (9.55), Ld � (0.05ƒy ��� / �ƒ�)d c b where ƒy � 60,000
psi; � � 1.3 for ‘‘top’’ bars; � � 1.0 for uncoated bars; � � 1.0 for normal-weight concrete; ƒ�c � 4,000 psi; and db �
1.0 in. Thus, Ld � (0.05 � 60,000 � 1.3 � 1.0 � 1.0 / �4,000)(1.0) � 61.7
or 62 in.