18 Questions
What is the percentage of f c represented by point C in Fig. 3-12a?
107 percent
What type of stress state exists in the webs of beams?
Biaxial tension–compression
Why is the splitting tensile strength less than the flexural tensile strength?
Due to the difference in biaxial stress state
What happens to the strength and stiffness of concrete under compression parallel to the cracks in cracked reinforced concrete?
They decrease
What is the primary reason why cracking does not represent failure of a reinforced concrete member?
The reinforcement resists the tensile forces after cracking
What is the primary cause of failure in zones 1 and 2 in Fig. 3-12?
Cracking of concrete
What is the primary purpose of the relationship shown in Figure 3-8?
To provide guidance on when forms can be removed
What is the effect of a very slow rate of loading on the axial compressive strength?
It reduces the strength to about 75% of the standard test strength
What is the approximate strain rate experienced during the standard cylinder test?
10 microstrain/sec
What is the purpose of capping and testing cores drilled from a structure?
To determine the compressive strength of concrete
What is the approximate percentage of the standard test strength reached at a rate of 30,000 psi/sec?
115%
What is the primary advantage of using Figure 3-8 for determining when forms can be removed?
It provides general guidance, but is not a sole determinant of adequate strength
What type of stress distribution occurs across the vertical diameter of a concrete specimen?
High transverse compression at the top and bottom, with nearly uniform tension elsewhere
What is the relationship between the modulus-of-rupture strength and the splitting tensile strength of concrete?
The modulus-of-rupture strength is 1.5 times the splitting tensile strength
What is the approximate relationship between the tensile strength and compressive strength of concrete?
The tensile strength is proportional to the square root of the compressive strength
What is the typical decrease in strength observed when the volume of concrete under high tension is increased?
A general decrease in strength, but the exact percentage varies
What is the equation used to compute the splitting tensile strength of concrete from a split-cylinder test?
fct = 2P / d
What is the average ratio of the direct tensile strength to the splitting tensile strength of concrete?
0.86
Understanding the relationship between concrete maturity and compressive strength, and the limitations of using maturity as a determinant of adequate strength. Includes factors affecting concrete strength and the standard cylinder test.
Make Your Own Quizzes and Flashcards
Convert your notes into interactive study material.
Get started for free
