Fire protection for Buildings

Fire protection is one basic need in a building today, it can be given the first priority in a hospital due to what extinct the damage could cause, simply saying it’s a killing machine.
Fire eats every thing in its path.

Fire Detectors and alarms

Detection of a potentially dangerous rise in air temperature or pressure or the presence of smoke is required at the earliest possible moment to start an alarm . Evacuation of the hospital complex building and manual or automatic contact with the fire brigade monitoring switchboard should take place before people are at risk. Means of detection can be combined with security surveillance.

Hospital needs to have the following diction methods in order to prevent a devastating fire.

Hazard Detectors

Hazard Detectors give an early warning of the risk of a fire or explosion.

Temperature Rise: A local rise in temperature leads to the melting of a fusible link in a wire holding open a valve on a fuel pipe to a burner, thermal expansion of a fluid-filled bellows or capillary tube or movement of a bimetallic strip to make an alarm circuit.

Flammable vapour detector: Gas, oil petrol, or chemical vapour diffusion through a membranes is detected.

Diffusion: Butane and propane vapour diffusion through a membrane is detected.

Explosion: Rise of local atmospheric pressure above a set value, or at a fast rate, is detected.

Ionization smoke detector 

ionization smoke detectors contain a radioactive source of around 1 microcurie, typically americium- 241, which bombards room air within the detector with alpha particles ( ionization).  Electrical current consumption is 50 micro ampere. The presence of smoke reduces the flow of alpha ions; the electric current decreases and at a pre-set value an alarm is activated.


visible smoke detector

 A source of light is directed at a receiving photocell. Smoke obscures or scatters the light and an alarm is triggered.

Laser beam 

A laser beam is refracted by heat or smoke away from its target photocell and an alarm is initiated. A continuous or pulsed infrared beam can be transmitted up to 100 m and can be computer – controlled to scan the protected area. It can also serve as an intruder alarm.


Closed-circuit television 

Manned security monitoring also as fire and smoke detection. Infrared imaging cameras reveal overheating of buried pipes and cables and can detect heat sources unseen by visual techniques.



Fire alarms are a statutory requirement. Audible bells, sirens, klaxons, hooters and buzzers are arranged so that they produce a distinctive warning. A visual alarm should also be provided throughout a building. Breakable glass call points are located 1.4 m above floor level within 30 m of any part of the premises.

Fire protection concept 

Although fires in buildings can be avoided, they nevertheless occur. Some of the reason for this is human error, arson, faulty electrical equipment, poor maintenance of heating equipment, and natural causes, such as lightning. Consequently building should be desingned to minimize the probability of a fire and to protect life and to limit property damage if a fire should occour, the minimum steps that are to be followed are as follows:

- limit potential fore loads, with respect to both combustibility and ability to generate smock and toxic gases.
- Provide means for prompt detection of fires, with warning to occupants who may be affected and notification of the presence of fire to fire fighter.
- Communication of instruction to occupants as to procedures to adopt for safety, such as to staying in place, proceeding to a designated refuge area, or evacuating the building.
- Provide mean for early extiguishment of any fire that many occur, primarily by automatic sprinklers but also by trained fire fighter.
- Make available also for fire fighting an adequate water supply, appropriate chemicals, adequate- size piping, conveniently located valves on the piping, hose, pumps, and other equipment necessary.
- Prevent spread of fire from building to building, either through adequate separation or by enclosure of the building with incombustible materials.
- Partition the interior of the building with fire barriers, or divisions, to continue a fire to a limited space.
- Enclose with protective materials structural components that may be damaged by fire (fore proofing)
- Provide refuge areas for occupants and safe evacuation routes to outdoors.
- Provide means for removal of heat and smoke from the building as rapidly as possible without exposing to these hazards, with the air-conditioning system, if one is present, assisting the removal by venting the building and by pressurizing smoke proof towers, elevator shafts, and other exits.
- For large buildings like this Hospital, install standby equipment for operation in emergencies of electrical system and elevators.

 Oshkosh; Fire truck

Common Engineering Terms used

If your an engineer, you must be able to know all the common engineering terms. following are few common ones.


Stress terms
Stress is the internal distribution of forces within a body that balances and reacts to the loads applied to it. It is a complicated tensor quantity that can be broken down into simpler elements for engineering purposes;

• Compressive stress (or compression) is the stress state when the material tends to compact (volume decrease). A simple case of compression is the uniaxial compression induced by the action of opposite, pushing forces. Most materials can carry compressive stress, even the granules such as sands. 
• Tensile stress is a loading that tends to produce stretching on a material by the application of axially directed pulling forces. Materials can withstand some tensile loading, but if enough force is applied, they will eventually break into two parts. Steel is an example of a material with high tensile strength. 
• Shear stress is caused when a force is applied to produce a sliding failure of a material along a plane that is parallel to the direction of the applied force e.g. when cutting paper with scissors. 

Strength terms

• Compressive strength is a limit state of compressive stress that leads to compressive failure in the manner of ductile failure (infinite theoretically yield) or in the manner of brittle failure (rupture as the result of crack propagation, or sliding among a weak plane - see shear strength).
• Tensile strength is a limit state of tensile stress that leads to tensile failure in the manner of ductile failure (yield as the first stage of failure, some hardening in the second stage and break after a possible "neck" formation) or in the manner of brittle failure (sudden breaking in two or more pieces with a low stress state).

Strain - Deformation terms

• Deformation of the material is the change in geometry when stress is applied (in the form of force loading, gravitational field, acceleration, thermal expansion, etc.). Deformation is expressed by the displacement field of the material.
• Strain or reduced deformation is a mathematical term to express the trend of the deformation change among the material field. For uniaxial loadings - displacements of a specimen (for example a bar element) it is expressed as the quotient of the displacement and the length of the specimen. For 3D displacement fields it is expressed as derivates of displacement functions in terms of a second order tensor (with 6 independent elements).
• Deflection is a term to describe the magnitude to which a construction or structural element bends under a load.

Stress - strain relations

• Elasticity is the ability of a material to return to its previous shape after stress is released. In some materials, the relation between applied stress and the resulting strain is directly proportional (up to a certain limit), and a graph representing those two quantities is a straight line. Hooke's law describes such relationships and is valuable in the study of springs. (see Solid mechanics). In other materials, the relation is not linear. In steel, the most common material for making springs, most of the elastic range is linear, though the relation becomes non-linear at the extreme end, just before the material begins to deform plastically.
• Plasticity is the property of materials to deform permanently after force is applied and released. Most solid materials behave elastically when relatively low amounts of force are applied, and plastically under higher amounts of force.

Design terms

• Ultimate strength is an attribute directly related to a material, rather than just specific specimen of the material, and as such is quoted force per unit of cross section area (N / m2). For example, Ultimate Tensile Strength (UTS) of mild steel is 470MegaN / m2. It is useful to remember that 1Pa = 1N / m2.
• Factor of safety is a design constraint that an engineered component or structure must achieve. FS = UTS / R, where FS: the Factor of Safety, R: The acting force (or stress) and UTS: the Ultimate force (or stress). For example to achieve a factor of safety of 4, the allowable stress in a mild steel component can be worked out as R = UTS / FS = 117.5MPa.

laboratory test on expansive soils- Swell Test

The most important laboratory test on expansive soils is the swell test. The standard one-dimensional consolidation test apparatus can be used. A standard consolidometer can accommodate a remolded or undisturbed sample from 2 to 4.25 in. diameter and from 0.75 to 1.25 in. thickness. Porous stones are provided at each end of the specimen for drainage or saturation. The assembly is placed on the platform scale table and the load is applied by a yoke actuated by a screw jack. The load imposed on the sample is measured by the scale beam, and a dial gage is provided to measure the vertical movement.

The advantage of such arrangement is that it is possible to hold the upper loading bar at a constant volume and allow the measurement of the maximum uplift pressure of the soil without a volume change. This requires a constant load adjustment by an operator. An advanced scheme is an automatic load increment device that measures swelling pressure without allowing volume change to take place.

The consolidometer can also be used to measure the amount of expansion under various loading conditions. Since swelling pressure can be evaluated by loading the swelled sample to its original volume, it is simple to convert the platform-scale consolidometer into a single-lever consolidation apparatus. Such a modified con- solidometer can be made locally at low cost. The average soil laboratory should have a train of such apparatuses to speed up the testing procedure.

It is important for the geotechnical engineer not to confuse “swell” with “rebound.” All clays will rebound upon load removal, but not all clays possess swelling potential. The use of graduated cylinders to measure the swelling potential of clay upon saturation is not a standard test. Such a test has been abandoned and should not be repeated.

what do we know about bitumen

what is bitumen? 
Bitumen or Tar is a dark black,greasy, viscous material that is a naturally-occurring organic byproduct of decomposed organic materials ,Bitumen is  the heaviest, thickest form of PETROLEUM.

How is bitumen produced?
Crude oil is to be introduced to an oil refinery, the crude oil being processed is separated into different parts on the basis with respect to their boiling range. The final bitumen product can be produced to technical specification either directly in the refining process or by blending bitumens with different physical properties.

What is the bitumen used for?

it been used widely for roads, roofs, water proofing..

Heavy duty pavings, Urban roads paving, rural roads paving, main roads paving, industrial uses.

Heavy duty paving is used in Airports, ports and railways require paving solutions that can withstand extremely heavy loads and high pavement stress. These pavements are subject to sustained loads, often in channels such as loading bays which can lead to rutting.

Industrial applications for bitumen are extremely varied; core applications include roofing, flooring and sealing on both an industrial and DIY level.

Use of Admixtures (chemicals) in Mixing Cement concrete

 


Chemicals or Admixtures when concreting is widely used all over the world today. admixtures are chemicals which are added to cement while or after concrete has been mixed with Aggregates and Sand. there are various types admixtures, and each admixture has its own use, the amount of admixture added to concrete is dependent to the type of chemicals used in it. 


Most of the admixtures are ready to use, no need of doing your own experiments on it. 


ASTM C 494, “Standard Specification for Chemical Admixtures for Concrete,” classifies admixtures into seven types as follows;

Type A - Water-reducing admixtures;
Type B - Retarding admixtures;
Type C - Accelerating admixtures;
Type D -  Water-reducing and retarding admixture;
Type E -  Water-reducing and accelerating admixtures;
Type F - Water-reducing, high-range, admixtures; and
Type G - Water-reducing, high-range, and retarding admixtures




Type A - Water-reducing admixtures
this type will reduce the amount of water needed for the mix, there for it increases the concrete strength,  its useful when concrete is been pumped by pump or tremi. Type A reduces water content by 5 to 15%, Typically the dosage rate of Type A water-reducers range from 130 to 390 mL per 100 kg (2 to 6 fl oz. per 100 lb) of cementitious materials. Higher dosages may result in excessive retardation of the concrete setting time.


Type B - Retarding admixtures and Type D -  Water-reducing and retarding admixture

Both of this is to offset the unwanted effect of temperature, since cement is exothermic and weather temperature place a roll too, this formula is needed on hotter weather conditions,  factors depending are; admixture concentration, dosage rate, concrete proportions, and ambient and concrete temperatures.


Type C - Accelerating admixtures and Type E -  Water-reducing and accelerating admixtures

both this shortens the setting time and accelerates the early strength of concrete. mostly used in freezing temperatures.