In: Civil Engineering
There are two steel I beams in a construction cite. The I beam A has 3" long stringer in the middle of the beam in the center of shear web and the second beam (beam B) has multiple edge cracking (0.1" deep) due to improper rolling process in the same middle area as beam A in both top and bottom flanges. As an engineer discuss which of the discontinuities will be more likely to be considered as a defect? Why?
The discontinuity in beam B will be more likely to be considered as defect.
Explanation-
Cracks directly affects the tensile and compressive strength of the beam.
Since the cracks is in the top and bottom of the beam so moment carrying capacity of the beam reduces.
Cracks directly affects the serviceability, stability and durability of the beam.
The crack is an evidence of gradual deterioration and causes damage to the beam .
The crack is a structural defect consisting of complete or incomplete separation within a single element or between contiguous elements of construction.
Cracks can also be defined as a line along which a material is broken into parts.
Every crack indicates that the beam is becoming unsafe.
Therefore, correctly assessing the importance of cracks is essential.
Many cracks have similar appearance, but their causes are different. An engineer should have a sound knowledge of causes, effect and types of cracks .
The side effect of cracks affects the integrity, permeability, structural and mechanical properties of the beam.
Cracks is classified as structural or non-structural.
It is also significant to assess causes of cracks through measurement of cracks characteristics, which are location, nature, direction, width, depth, position and extent of cracks, and how to repair them.
Cracks may vary in width from very thin hair cracks barely visible to naked eye about 0.01 mm in width to gaping cracks 5 mm or more in width.
A commonly known classification of cracks, based on their width are- (a) thin - less than1 mm in width, (b) medium- I to 2mm in width and (c) wide- more than 2 mm in width.