BASICS OF STRUCTURAL ENGINEERING 

PART -1

LEARN STRUCTURAL TIPS

v   Force

A force is an interaction that causes an affected object to be pushed or pulled in a certain direction.

v   Mass

A measure of how much matter is in an object.

Mass is commonly measured by how much something weighs. But weight can change for different locations (such as on the moon) while the mass stays the same.

Mass is measured in grams, kilograms and, tones (Metric) or ounces and pounds (US units).

v   Acceleration

Acceleration is the name we give to any process where the velocity changes. Acceleration is the rate of change of velocity with time.

An apple is falling down. It starts falling at 0 meters per second. At the end of the first second, the apple is moving at 9.8 meters per second. The apple has accelerated. At the end of the second, the apple is moving down at 19.6 meters per second. The apple has accelerated again.

The role of acceleration in structural engineering we will discuss in static and dynamic analysis of structures.

v   Moment

Momet Nothing But the force multiplied by its perpendicular distance and also, we can say that the Moment of a force is a measure of its tendency to cause a body to rotate about a specific point or axis. This is different from the tendency for a body to move, or translate, in the direction of the force. In order for a moment to develop, the force must act upon the body in such a manner that the body would begin to twist.

Following the above picture the Weight F is the force and D shows perpendicular distance from the point of force and M is the moment so we can say that.

M= F x D

v   Stress

Before going to discuss the stress and strain we need to understand the Tension and Compression forces and their behavior.

TENSION:	Pulling force
	Imagine the force felt in your arms while you hang from a bar.
	A structural element subjected to tension is elongated.
COMPRESSION:	Squeezing force
	Imagine the force felt in your arms while you stand on your hands.
	A structural element subjected to compression is shortened.

STRESS:

In simple words, stress is the internal resistance offered by the body against externally applied load.Stress also defined as the force per unit area that the force acts upon. As we know that Stress are either compressive or tensile, the Structural materials are chosen by their ability to resist tensile or compressive forces, depending upon the application.  Most of the materials are better at resisting one or the other. Like, concrete is strong in compression and relatively weak in tension. Steel is equally strong in tension and weak in compression.

As you can check the figure 1 and 2 Two persons are doing exercise , don’t worry this not a gym class and I am not going to teach you here how to build six pack , just I would like to explain that If your hanging on a bar the tensile force will act on your arms that is mentioned as T and if you walk on your hands the compression force will act on your arms that is mentioned by C.

v    Strain   

When an external force is applied on a body, there is some change occur in the dimension of the body. The ratio of this change of dimension in the body to its actual length is called strain

If you would like to understand clearly, A Body consist of small molecules and particle’s, between which forces are acting. These molecular forces resist the change in the form of the body which external forces tend to produce. Is such an external force applied to the body its particles will displaced and the mutual displacements continue until the equilibrium established between the external and internal forces in such a case the body in a state of strain.

Strain has no units because it is a ratio of lengths.

v   Deflection

 It Refers to the movement of a beam from its original position due to the forces being applied to the member. Deflection, also known as displacement, can occur from external applied loads or from the weight of the structure itself. It can occur in beams, trusses, frames and basically any other structure. To define deflection, let's take a simple cantilevered beam with Load (P) acting at the end this force will cause the beam to bend and deflect from its natural position the  is the deflection of the beam.

 It measures the physical displacement of a member under a load.

                                                                         

v   Shear force

Shear means the tangential force acting along the cross section of the member, we need to understand the practically to get the concept.

consider one wooden piece and cut it along with the cross section the force generated along the cross-sectional plane that force will come under the shear force.

Shear force and bending moment are used to check the strength of beam. I.e. how much shear force or bending moment beam can bear before permanent deformation.

v   Bending moment

The bending moment defined as the algebraic sum of all the moments either left or right of the section this what we read but we need to understand it different ways to get complete picture on the subject of bending moment …like A bending moment is the reaction induced in a structural element when an external force or moment is applied to the element causing the element to bend. The most common or simplest structural element subjected to bending moments is the beam.

When you bend a ruler, even though apply the forces/moments at the ends of the ruler, bending occurs all along the ruler, which indicates that there is a bending moment acting all along the ruler. Hence bending moment is shown on a bending moment diagram.

The bending moment plays a major role in designing the structures , once we apply the load on a member it will tends to bend the member and steadily the bending stresses will generate along the member after a certain duration the member will subject to large deformations it leads to the deflection in the member and finally the member get cracked and the life of the structure will becomes less.

The section of the member also having importance in the system since the moment of resistance of the structure directly related to the moment of inertia and moment of inertia consist of the sections of the members since we use the rectangular sections for main structural columns then circular if you calculate the moment of inertia of the rectangular member it shows greater value than circular , if the moment of inertia less it leads to reduce the section modulus and also reduce the moment of resistance of the member usually we use the circular column for architectural appearance with large diameters it leads to uneconomical. this relation we can find in Theory of simple bending equation

v   Axial force

Axial force is a general term, meaning, "force along the axis".

Axial Force is generally defined as the Force acting along the axis of the component / assembly. For example, consider a cylindrical Building column/ Square column. The column is a structural member of a building and it is designed to take Axial Compression force. Similarly, the circular rod in the ceiling fan is designed to take Axial Tension Force + Torque due to rotating fan.

Axial force can be in Tension/ Compression as defined in the examples above.

If you understand the load transfer from one element to other elements ,usually the dead and live loads from the floors it will transfer to the beams and from the beam it will distribute to the columns finally the reaction will reach to the foundation and then it will transfer to the soil.

Units-KN

LEARN STRUCTURAL TIPS

WHO IS  STRUCTURAL ENGINEERS AND WHAT THEY DO

👆👆👆Imagine if structural engineers are following the above concept there will be more accidents on the street and finally structure engineers will become fractured engineers, Can we compare structural engineers with doctors? This may sound strange but let’s find out.

Structural engineers design the skeleton of a building to achieve acceptable probability so it could provide satisfactory performance during its entire life. Like doctors, they treat the human body by analysing body conditions first and once diagnosis is identified, they continue with appropriate treatments and how to maintain the body from functioning normally and healthy.  Both professions are somewhat identical and the aim is to satisfy, correct and avoid all the conditions from resulting to failure to extend its lifespan.   

                                                  

                                         On the other hand, doctors examine their patients to diagnose their conditions. If necessary, they write recommendations for laboratory testing to support their diagnosis and to know the root of the problem. They also write prescriptions and advice like changing one’s lifestyle, they ideally read more books to learn more in their chosen profession, update themselves by learning how to use updated medical equipment to make safe and efficient treatments for their patients unlike structural engineers also need to upgrade with software's. For short, most doctors make   correcting measures for an existing built human structure.

While structural engineers they start from calculating stability, strength and rigidity of the structure before building it. They test and examine the structure to control and avoid failures. They also need Soil laboratory tests before they introduce their structural design.  

Structural Engineering is among the oldest type of engineering, dating back to the first instance of tree branches being lashed together with vines to make a shelter. Throughout history it has been recorded that people have been designing and building increasingly larger and more sophisticated structures. Beginning from primitive huts to international high-rise buildings. 

Structural Engineering in an integral part of Civil Engineering in which engineers are educated to create the ‘bones and muscles’ that creates the form and shape of man-made structures. The role of each structural engineer is a key component in the construction process, it is a part of the wider discipline of civil engineering.

               It Involves Analysis design, construction and maintenance of structures that reinforces or counteract loads, such as buildings, skyscrapers, dams and bridges. Unlike Architects, who focuses on the appearance, shape, size and use of the building, Structural Engineers must solve technical problems taking things into consideration like battling gravity, wind, earthquake, weather conditions to provide the world with outstanding structures.

Structural engineers often specialise in particular types of structures, such as buildings, bridges, pipelines, industrial, tunnels, vehicles, ships, aircraft and spacecraft vision for the project.

Structural engineers design roof framing (beams, rafters, joists, trusses), floor framing (floor decks, joists, beams, trusses, girders), arches, columns, braces, frames, foundations and walls. The materials they use include steel, concrete, wood, masonry, and aluminium.

                                     As an entry-level structural engineer, they may design individual structural elements of a particular structure, such as the beams and the columns of a building. More experienced engineers may be responsible for the structural design and integrity of an entire system, such as a building and sometimes they do inspection to ensure that the ongoing work exactly matching with the approved drawings.

Don’t take it too seriously guys, this is how architects and structural engineers make fun with each other but there is truth in the joke. 

Joking aside, the development of specialised knowledge of structural theories appeared during the 19th and early 20th centuries, the professional structural engineers come into existence since 1990s. Specialised software has become available to aid in the design of structures, with the functionality to assist in the drawing, analysis and designing of structures with maximum precision; examples software include AutoCAD, Staadpro, ETABS, Safe , Prokon, Revit Structure, etc. Such software's may also take into consideration environmental loads, like earthquakes and winds.                                                   

                                          Structural Engineers should not depend on the software alone. Ideally, they should practice at least with 3 or 4 buildings by manual calculation to acquire the behaviour of structure element-wise and as well material properties. They can prepare their own excel sheets to save their time for manual calculations and then they can go ahead with the use of software. Nowadays, we can see that a lot of juniors are immediately using CSI and other software's without having any basic knowledge in structural designing. I would like to stress that this field is not video game to essentially use mouse and keyboards for making the dummy structures (A non-technical person can also do the modelling of the building) Structural design requires major responsibility aiming to produce safe, stable and economical structure.  For structural work, a municipality license can be obtained only after completing a prescribed amount of education and work experience.  

 Have a fun with the below pictures......😍😂

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