Mohammad Nurunnabi

WSD- WORKING STRESS DESIGN: Stress condition of structural member under working load is given attention. Full strength of material is not utilizd and is reduced by a factor. Stresses calculated are within the elastic limit. Is less economical than USD. USD- ULTIMATE STRESS DESIGN: Focuses on the strength capacity of the members at conditions corresponds to failure. Material properties are assessed and used in design. Loads are multiplied by a factor. More economical   

The Working, Allowable or Permissible stress method is an elastic design method. In this design method, members are designed to never go beyond their elastic range. The primary benefit of this benefit is that the same loads used for checking flexural, shear, torsional and axial design can also be used for serviceability checks, ie. the loads are not amplified. This reduces book keeping efforts and removes one potential source of error introduction. In practice, this means it is simpler. Limit State or Load Resistance Factor design uses the ultimate strength of a member, beyond initial yielding, to determine the allowable strength. The primary benefit of the limit state design method is that it is generally produces more economical designs than Working Stress Methods, and it provides a more consistent safety factor across all elements.  LRFD allows for more control and understanding of the structural behavior by explicitly considering each load type independently.  In practice, the two

TMT stands for Thermo Mechanically Treated. The TMT bars have a hard outer surface and a softer core. Their manufacturing process includes hot rolled steel wires passed through water. This makes the surface hard and keeps the core warmer and softer. This helps in making the steel corrosion resistance and also increase its weldability.  Technically TMT means a type of quenching and tempering process and it would not be precise to call it a Thermal+Mechanical treatment. Because, even the HYSD bars are treated at high temperatures and then rolled and twisted for shaping and hence it is also thermally + mechanically treated. So the difference lies in the exact process of making these two types of bars and not just in their names. On the other hand, HYSD stands for High Yielding Strength Deformed bars. These bars have more yield strength than Mild Steel. Unlike TMT bars, HYSD bars are both hot or cold worked. They are graded as Fe 415 or Fe500. HYSD = Torsed/twisted steel (TOR Steel Bars

A  refractory  material is one that retains its strength at high  temperatures .  ASTM  C71 defines refractories as "non-metallic materials having those chemical and physical properties that make them applicable for structures, or as components of systems, that are exposed to environments above 1,000 °F (811 K; 538 °C)". Refractory materials are used in linings for  furnaces ,  kilns ,  incinerators  and  reactors . They are also used to make  crucibles  and moulds for casting glass and metals and for surfacing flame deflector systems for rocket launch structures. Refractory materials Refractory materials must be chemically and physically stable at high temperatures. Depending on the operating environment, they need to be resistant to  thermal shock , be chemically inert , and/or have specific ranges of  thermal conductivity  and of the coefficient of  thermal expansion . The  oxides  of  aluminium  ( alumina ),  silicon  ( silica ) and  magnesium  ( magnesia ) ar

It is essential to know the type of bricks Bricks for properly understanding the masonry work. Brick can be many types depending on its quality, making process, its raw material and purpose of their using. In this post I'll describe the brick types for various criteria. Depending on quality, bricks are three type - First class brick Second class brick, and Third class brick. First class brick : These bricks are made from good quality raw materials. Color of first class brick is uniform. These are regular in size and shape and doesn't absorb more than 20% water of its own dry weight when immersed in fresh water for 24 hours. The crushing strength of this type of brick should be 105 kg/cm2. Read More: 6 of Good Quality Brick 3 Most Important Properties of Brick Second class brick : The quality of bricks of this type is little bit less from first class brick. Such as it can be slightly over burned. She size and shape can be slightly differ from standard. The crushing str