Statically Determinate and indeterminate Beams

Structure is generally classified into two categories as Determinate and Indeterminate Structures or Redundant Structures for analysis of structures to find forces based on criteria discussed below. Structure is an assemblage of a number of components like slabs, beams, columns, walls, foundations and so on, which remains in equilibrium. It has to satisfy the fundamental criteria of strength, stiffness, economy, durability and compatibility, for its existence. Any structure is designed for the stress resultants of bending moment, shear force, deflection, torsional stresses, and axial stresses. If these moments, shears and stresses are evaluated at various critical sections, then based on these, the proportioning can be done. Evaluation of these stresses, moments and forces and plotting them for that structural component is known as analysis. Determination of dimensions for these components of these stresses and proportioning is known as design.

Determinate structures are analysed just by the use of basic equilibrium equations. By this analysis, the unknown reactions are found for the further determination of stresses. Redundant or indeterminate structures are not capable of being analysed by mere use of basic equilibrium equations. Along with the basic equilibrium equations, some extra conditions are required to be used like compatibility conditions of deformations etc to get the unknown reactions for drawing bending moment and shear force diagrams. Example of determinate structures are: simply supported beams, cantilever beams, single and double overhanging beams, three hinged arches, etc. Examples of indeterminate structures are: fixed beams, continuous beams, fixed arches, two hinged arches, portals, multistoried frames, etc. Special methods like strain energy method, slope deflection method, moment distribution method, column analogy method, virtual work method, matrix methods, etc are used for the analysis of redundant structures.
 
Indeterminate Structures: A structure is termed as statically indeterminate, if it can not be analysed from principles of statics alone, i.e. clip_image001. A statically indeterminate structure may be classified as:
Externally indeterminate, (example: continuous beams and frames)
Internally indeterminate, (example: trusses )
Both externally and internally indeterminate, (example: trussed beams, continuous trusses )

WASTEWATER TREATMENT prepared by Mrs Ancy

STEPS IN WASTEWATER TREATMENT

1.    SCREENING AND PUMPING
The incoming wastewater passes through screening equipment where objects such as rags, wood fragments, plastics, and grease are removed. The material removed is washed and pressed and disposed of in a landfill. The screened wastewater is then pumped to the next step: grit removal.

2.    GRIT REMOVAL
Grit settles by gravity into the bottom of the tank (in a grit hopper) while effluent exits at the top of the tank. The grit that settles into the grit hopper may be removed by a grit pump or an airlift pump. A detritus tank (or square tank degritter) is a constant-level, short-detention settling tank.

3.    PRIMARY SETTLING.
Primary settling is the process by which the velocity of the sewage is reduced below the point at which it can transport the suspended matter, so that much of this settles and can be removed as sludge.

4.    AERATION / ACTIVATED SLUDGE.
Aeration in an activated sludge process is based on pumping air into a tank, which promotes the microbial growth in the wastewater. ... After settling in a separate settling tank, bacteria forming the "activated sludge" flocks are continually recirculated back to the aeration basin to increase the rate of decomposition.
 
5.    SECONDARY SETTLING.
Secondary settling is the final step of the activated sludge-based biological wastewater treatment. Secondary settling tanks (SSTs) are therefore an essential unit of producing a clear effluent.

6.    FILTRATION
Filtration is a physical, biological, or chemical operation that separates solid matter and fluid from a mixture with a filter medium that has a complex structure through which only the fluid can pass.

 
7.    DISINFECTION
Killing, removal, or deactivation of harmful microorganisms can be referred to as disinfection. Destruction or deactivation of pathogenic microorganisms results in stopping their reproduction and growth. People may fall ill by consuming the contaminated water containing the pathogenic microorganisms.

8.    OXYGEN UPTAKE
Aerobic capacity is commonly described by the o₂max, or maximal oxygen uptake. This measurement is an indication of (1) the ability of the cardiovascular system to provide oxygen to working muscles and (2) the ability of those muscles to extract oxygen for energy generation in the form of adenosine triphosphate (ATP).