A) .Among the most popular building materials, steel and concrete are often used
for the underlying framework of construction projects. This page offers a general
comparison of the many materials, each of which has benefits and drawbacks like
any engineering choice. For all purposes, there is no material that can be deemed
superior to another, and the best choice depends on the particulars of the
project. In contrast to building fires, which typically reach temperatures about
2,000°F, structural steel melts at about 2,500°F. Steel structures are not
necessarily safe despite the rarity of steel melting. Keep in mind that when
subjected to high temperatures, the material deforms and loses strength. As a
safety measure, structural steel is required by building codes to be protected
from fire.
Steel that has been fireproofed will ensure that a structure maintains its shape in
the case of a fire, enabling people to flee if necessary. Commercial structural steel
must, among other things, achieve the 2-hour fire resistance grade. The standard
ratings are at 2, 3, and 4 hours. Fabricators of structural steel who are certified by
AISC can meet your fireproofing requirements. Construction delays will result
from fireproofing on site, regardless of whether a fireproofing specialist or the
construction team does the work. The worksite will require employees to move
about.
To prevent someone from tripping over wet foam or paint, areas will need to be
sealed off, and materials must be totally dry before final installation. Another
disadvantage is that elements fabricated by certified fabricators off-site do not
require the extra inspection needed to assure proper fireproofing. Structural steel
fireproofing can mean the difference between a building's entire structure being
damaged in a fire and collapsing completely. In conjunction with active measures
like fire sprinklers, passive fire prevention makes buildings safer for tenants while
safeguarding the owner's investment.
b) The metal's ductility is a physical characteristic that ensures that it will stretch
rather than break if pulled. The capacity of a material to experience significant
plastic deformation under tensile stress before to rapture is referred to as its
ductile characteristics. Nickel, copper, steel, etc. are examples of ductile
materials.
As the carbon content increases:
The ultimate strength of steel increases.
The elongation before fracture decreases.
The ductility of the metal decreases
Weldability is likewise decreased as carbon content rises, notably at 0.25%
carbon.
Ductility and plasticity are comparable.
Carbon is typically the most significant commercial steel alloy. Hardness, strength,
and improved hardenability all rise with carbon concentration. For a wide range
of functions and applications, steel has several key qualities. These characteristics
are greatly influenced by the carbon content. 90% of all steel is composed of
alloys that mostly include carbon.
c) A concrete stress-strain curve illustrates the behavior of concrete under load.
Plotting concrete compress strain over time with varying concrete compressive
loads results in its creation (stress). The compressive stress strain curve of
concrete is of great importance since it is typically employed in compression.
Concrete cylinder specimens are tested utilizing compressive test equipment at a
28-day old age to determine the stress and strain of the material. Designers and
engineers can foresee how concrete used in building structures would behave
according to the concrete's stress-strain curve.
Ultimately, the relationship between the stress-strain curve and the sort of stress
that the concrete is subjected to in the structure determines how well a concrete
structure performs.
Figures depict the strain Typical weight and light weight concrete have different
stress curves. Each illustration features a series of curves that stand in for the
concrete's strength. Hence, higher curves indicate greater concrete strength. The
concrete stress-strain curve's shape is depicted in Fig. 3 as it varies with the rate
of loading. Although the pace of testing and concrete density have an impact on
the stress-strain curve's shape, all curves appear to have a similar personality. i.e.,
they experience the same stages when loaded. The following sections of the
concrete stress stain curve are discussed
d)
A: Upper yeild point
B: Lower yeild point
C: Beginning of strain hardening
D: Ultimate stress point
E: Fracture Point
Solid materials can be divided into two groups based on their capacity to stretch
in the presence of external loading: brittle and ductile. Ductile materials display
significant plastic deformation when subjected to external force, whereas brittle
materials only show minimal plastic deformation. Here are some comparisons and
contrasts between brittle and ductile materials.
Brittle deformation is the irreversible strain that occurs when rocks fracture under
stress. Brittle behavior is exhibited by any substance that shatter into pieces.
When rocks flow or bend in reaction to stress, it is known as ductile deformation
(ex. clay). Ductile materials can be easily stretched into wires and distort under
pressure with clear visible deformation. Because brittle materials do not deform
before to breaking and frequently fracture cleanly, they fracture rather than
stretch and can thus be readily put back together
References
 Book: Mechanics of Materials by F. P. Beer, E. R. Johnston and J. T. Dewolf (Tata
McGraw-Hill Education).
 Book: Callister’s Materials Science and Engineering by R. Balasubramaniam (Wiley
India).