Change List for this Rule


General Order 95


Section IV


Strength Requirements for All Classes of Lines

48.3       Concrete


A.      Reinforced Concrete

Values used for ultimate strengths of reinforced concrete, in conjunction with safety factors given in
Rule 44 , shall not exceed the following:


Reinforcing steel, tensile or compressive strength, pounds per square inch:-55,000


Concrete, 1:2:4


Compressive Strength

7 days

900 lbs per sq. in.

30 days

2,400 lbs per sq. in.

90 days

3,100 lbs per sq. in.

6 months

4,400 lbs per sq. in.


If reinforced concrete is designed for higher strength values which are proven by test, such values may be used in lieu of the figures given.


B.      Prestressed Concrete


The minimum strength of the materials used in prestressed concrete structures used in conjunction with the safety factors given in Table 4 shall be as follows:


Reinforcing Steel - yield strength          40,000 lbs per sq. in.


Prestressing Steel yield strength      188,000 lbs per sq. in.


Concrete - compressive strength at 28 days        4,000 lbs per sq. in.


Other strength values may be used provided the strength values used for design are proven by tests.


Note:      Rule 48.3B added on February 13, 1974 by Decision No. 82466.