SIMPLE ILLUSTRATION AND EXPLAINANTION OF CHARACTERISTIC STRENGTH AND CHARACTERISTIC LOAD

Before going in to designing part ,it’s very important to know some definitions and values. Characteristic strength and Characteristics load are one them, i will try to simplfy as possible.

Characteristic strength

Characteristics strength of a material is a value of that particular material,Below which not more than 5 % of the test result are expected to fail

To simply fir this.....

lets take an exmple

As per is code

The characteristics value of M15 concrete is 15 N/mm2

There fore....this value of M15 grade of concrete is a benchmark for us ...so that when we use M15 grade of concrete ...we can get the strength of 15 N/mm2.

And the probability of not getting the given value is only 5% that means we gat the value as 15 N/mm2 95% of the time.

And this theory is applied to any characteristics value given in the IS code.

Characteristics load

Characteristics load means those loads which have a 95% probability of not being exceeds during the life time of the structure.

These values are taken from IS 875 -1987

PART 1 – DEAD LOAD

PART 2 – IMPOSED LOAD

PART 3 – WIND LOAD

PART 4 – SNOW LOADS

PART 5 – SPECIAL LOADS AND LOADS COMBINATIONS

ALSO FOR EARCHQUAK LOADS IS 1893 – 2002 (PART 1 TO 5) IS CONSIDERED FOR DESIGN

 to simplify this definition...

Characteristics load is the values of different type of loads which required to consider at the time of designing any structures. And these values are the best values giving 95% accuracy.By taking the characteristics load values as described in the IS code it is considered that 95 % of the time these values or these type of loads on structure is not exceed during the life time of structures.