Safe work at height

Safe work at height

Fall from height are the most common cause of fatal and major injury to constructional workers ,Falls  from height are most common  causes of serious injury and the most common cause of manor injury to employee.
type of falls are slips ,trips ,high frequency rate and low injury severity rate etc.(STF)

falls from height were the most common cause of fatalities, accounting for nearly three in ten (29%) fatal  injuries to workers 
 slips & trips were the most common cause of major/specified injuries to employees, with falls from height the next most common 

 STFs were responsible for more than half (57%) of all major/specified and almost three in ten (29%) overseven-day injuries to employees, making up 36% of all reported injuries to employees (RIDDOR). 

Prevent and Arrest Falls From Heights

An apprentice carpenter was severely injured when he fell through a stairwell opening and landed on the concrete floor 37 feet below. In another incident, a roofer unhooked his lanyard from the lifeline and then slipped on frost, falling to his death, 53 feet below.

Every year workers die or are injured as a result of falling from ladders, scaffolds, roofs or other elevations. Falling is a risk faced by construction workers, painters, solar panel installers, window washers, firefighters, live performance workers, and others who work at heights. Ideally it would be safest to eliminate the risk all together by eliminating the need to work at heights, however in many occupations such as construction and other trades, this is not practical, and working at heights is a part of the job.

There are however, steps that employers and workers can take to minimize the risk, and help prevent falls and the injuries that go along with them.

Risk Assessment
Any work at heights should be properly planned, supervised, and not carried out in dangerous weather conditions. Conduct a risk assessment to identify and address any hazards related to the work to be performed. This information can help you select the right equipment for the job, and take adequate control measures and precautions to ensure the safety of workers and others.

Fall Protection Plan 
Laws vary by jurisdiction, however most require employers to develop a written, site-specific fall protection plan when employees are working over a certain vertical height (anywhere from 3-7.5 metres (10-25 feet)) and are not protected by permanent guardrails,. Be sure to check the applicable legislation for your jurisdiction. The plan should include the fall hazards and fall protection systems that are in place in each area, and the procedures for using, maintaining, fitting and inspecting fall protection equipment. The plan should also include procedures for rescuing a worker who has fallen, and is suspended by a personal fall protection system or safety net.

Training and Supervision
People working at heights must be trained in practical fall prevention and fall arrest techniques. Whenever personal protective equipment is used, the employer must ensure that workers know how to properly select, fit, use, inspect, and maintain the gear they will be using. The employer is responsible for providing appropriate training, and safety equipment that complies with safety standards, and ensuring that workers use the fall protection system provided at all times.

Fall Protection
If you are at risk for falling three meters (ten feet) or more, you should use the appropriate fall protection system when working. There are various fall protection methods and devices to protect workers who are at risk of falling. Each has their appropriate uses; depending on the situation, use one or more of these fall protection methods:

Guardrails should be installed at the edges of construction sites, roofs, and scaffoldings whenever possible to prevent falls. Standards for guardrails dimensions may vary from province to province.

Fall restraint systems such as work positioning devices that prevent workers from travelling to the edge of the building or structure must be provided if the use of guardrails isn't practicable.

Fall arrest systems (full body harnesses and safety nets) are used to stop workers in mid-fall to prevent them from hitting the surface below. Full body safety harnesses attached to secured lanyards are widely used, however to be effective, they must be fitted properly to each worker. Although a poorly fitting harness will stop a fall, it can injure the worker who is dangling in mid-air if the straps and metal supports are not contoured to the individual's shape.

The lanyard, or line that stops the fall, and the anchor point for the lanyard are just as important as the harness. Anchor points must be carefully planned, usually in consultation with an engineer, and the length of the lanyard must allow for the stretch in the material resulting from the fall. Manufacturers can provide information to help you choose the correct length and avoid contact with the ground or other objects.

Safety netting can be used effectively in construction of industrial framed buildings. Trained personnel are required to install, dismantle and inspect the netting, and no worker should work above nets without proper training.

Suspension Trauma
When fall arrest systems are used, the possibility of suspension trauma is a serious concern. This condition, which can be fatal, occurs when a person is suspended motionless in a vertical position in the harness while awaiting rescue. When a person is suspended vertically and perhaps in shock, blood tends to pool around the legs, putting extra pressure on the heart while it attempts to pump blood to the brain. The situation can be made worse by the constrictions of the harness. Suspended workers with head injuries or who are unconscious are particularly at risk. The person must be rescued quickly (under ten minutes) and gradually brought to a horizontal position to avoid potential cardiac arrest. This is why it is critical to have a rescue plan with procedures for rescuing a worker who is suspended by a personal fall protection system.

Preventing the fall, or rescuing the fallen, the best way to protect workers from injury is to create a culture of safety that values the input of both employers and workers.

Falls from Heights in Construction

Accidents and injuries like these can be

prevented

1. Use fall protection

Employers must ensure that a fall protection system is used when work is being done at a place:

• From which a fall of 3 metres (10 ft) or more may occur
• Where a fall from a lesser height involves an unusual risk of injury

Depending on the situation, one or more of the following fall protection methods must be used:

• Guardrails should be installed, whenever possible, to prevent workers from falling.
• Fall restraint systems such as work positioning devices that prevent workers from travelling to the edge of the building or structure must be provided if the use of guardrails isn't practicable.
• Fall arrest systems must be used whenever a fall restraint system isn't practicable. Fall arrest systems stop workers in mid-fall, preventing them from hitting the surface below. Examples include safety nets and full body harnesses attached by lifelines to secure anchors.
• Control zones can be used in certain cases. Control zones involve setting raised warning lines at a safe distance - 2 metres (6.5 ft) - from unguarded edges. A safety monitor is required to ensure that workers in the control zone work in a manner that minimizes their potential fall.
• Other fall protection systems and procedures acceptable to the WCB may also be used.

2. Properly instruct, train, and supervise workers

Before a worker is allowed into an area where a risk of falling exists, employers must ensure workers are trained in the safe use of the fall protection equipment they will be using.

3. Have a fall protection plan

A written fall protection plan is required if:

• Work is being done at a location where workers are not protected by permanent guardrails and from which a fall of 7.5 metres (25 ft) or more may occur
• The employer uses a safety monitor and control zone or other work procedures as the means of fall protection
• A fall may involve an unusual risk of injury

The plan must specify:

• The fall hazards in each area
• The fall protection systems in place for each area
• The procedures for using, maintaining, and inspecting fall protection equipment
• The procedures for rescue if a worker has fallen and is suspended by a personal fall protection system or safety net

Strength of materials

In materials science, the strength of a material is its ability to withstand an applied load without failure. The field of strength of materials deals with forces and deformations that result from their acting on a material. A load applied to a mechanical member will induce internal forces within the member called stresses when those forces are expressed on a unit basis. The stresses acting on the material cause deformation of the material in various manner. Deformation of the material is called strain when those deformations too are placed on a unit basis. The applied loads may be axial (tensile or compressive), or shear. The stresses and strains that develop within a mechanical member must be calculated in order to assess the load capacity of that member. This requires a complete description of the geometry of the member, its constraints, the loads applied to the member and the properties of the material of which the member is composed. With a complete description of the loading and the geometry of the member, the state of stress and of state of strain at any point within the member can be calculated. Once the state of stress and strain within the member is known, the strength (load carrying capacity) of that member, its deformations (stiffness qualities), and its stability (ability to maintain its original configuration) can be calculated. The calculated stresses may then be compared to some measure of the strength of the member such as its material yield or ultimate strength. The calculated deflection of the member may be compared to a deflection criteria that is based on the member's use. The calculated buckling load of the member may be compared to the applied load. The calculated stiffness and mass distribution of the member may be used to calculate the member's dynamic response and then compared to the acoustic environment in which it will be used.

Material strength refers to the point on the engineering stress–strain curve (yield stress) beyond which the material experiences deformations that will not be completely reversed upon removal of the loading and as a result the member will have a permanent deflection. The ultimate strength refers to the point on the engineering stress–strain curve corresponding to the stress that produces fracture.

Types of loadings[edit]

• Transverse loading - Forces applied perpendicular to the longitudinal axis of a member. Transverse loading causes the member to bend and deflect from its original position, with internal tensile and compressive strains accompanying the change in curvature of the member.^[1] Transverse loading also induces shear forces that cause shear deformation of the material and increase the transverse deflection of the member.
• Axial loading - The applied forces are collinear with the longitudinal axis of the member. The forces cause the member to either stretch or shorten.^[2]
• Torsional loading - Twisting action caused by a pair of externally applied equal and oppositely directed force couples acting on parallel planes or by a single external couple applied to a member that has one end fixed against rotation.

Stress terms[edit]

A material being loaded in a) compression, b) tension, c) shear.

Uniaxial stress is expressed by

where F is the force [N] acting on an area A [m²].^[3] The area can be the undeformed area or the deformed area, depending on whether engineering stress or true stress is of interest.

• Compressive stress (or compression) is the stress state caused by an applied load that acts to reduce the length of the material (compression member) along the axis of the applied load, it is in other words a stress state that causes a squeezing of the material. A simple case of compression is the uniaxial compression induced by the action of opposite, pushing forces. Compressive strength for materials is generally higher than their tensile strength. However, structures loaded in compression are subject to additional failure modes, such as buckling, that are dependent on the member's geometry.

• Tensile stress is the stress state caused by an applied load that tends to elongate the material along the axis of the applied load, in other words the stress caused by pulling the material. The strength of structures of equal cross sectional area loaded in tension is independent of shape of the cross section. Materials loaded in tension are susceptible to stress concentrations such as material defects or abrupt changes in geometry. However, materials exhibiting ductile behavior (most metals for example) can tolerate some defects while brittle materials (such as ceramics) can fail well below their ultimate material strength.

• Shear stress is the stress state caused by the combined energy of a pair of opposing forces acting along parallel lines of action through the material, in other words the stress caused by faces of the material sliding relative to one another. An example is cutting paper with scissors^[4] or stresses due to torsional loading.

Strength terms[edit]

• Yield strength its the lowest stress that produces a permanent deformation in a material. In some materials, like aluminium alloys, the point of yielding is difficult to identify, thus it is usually defined as the stress required to cause 0.2% plastic strain. This is called a 0.2% proof stress.^[5]

• Compressive strength is a limit state of compressive stress that leads to failure in a material in the manner of ductile failure (infinite theoretical yield) or brittle failure (rupture as the result of crack propagation, or sliding along a weak plane - see shear strength).

• Tensile strength or ultimate 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 that failure, some hardening in the second stage and breakage after a possible "neck" formation) or brittle failure (sudden breaking in two or more pieces at a low stress state). Tensile strength can be quoted as either true stress or engineering stress, but engineering stress is the most commonly used.

• Fatigue strength is a measure of the strength of a material or a component under cyclic loading,^[6] and is usually more difficult to assess than the static strength measures. Fatigue strength is quoted as stress amplitude or stress range (), usually at zero mean stress, along with the number of cycles to failure under that condition of stress.

• Impact strength, is the capability of the material to withstand a suddenly applied load and is expressed in terms of energy. Often measured with the Izod impact strength test or Charpy impact test, both of which measure the impact energy required to fracture a sample. Volume, modulus of elasticity, distribution of forces, and yield strength affect the impact strength of a material. In order for a material or object to have a high impact strength the stresses must be distributed evenly throughout the object. It also must have a large volume with a low modulus of elasticity and a high material yield strength.^[7]

Strain (deformation) terms[edit]

• Deformation of the material is the change in geometry created when stress is applied (as a result of applied forces, gravitational fields, accelerations, thermal expansion, etc.). Deformation is expressed by the displacement field of the material.^[8]
• Strain or reduced deformation is a mathematical term that expresses the trend of the deformation change among the material field. Strain is the deformation per unit length.^[9] In the case of uniaxial loading the displacements of a specimen (for example a bar element)lead to a calculation of strain expressed as the quotient of the displacement and the original length of the specimen. For 3D displacement fields it is expressed as derivatives 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 structural element is displaced when subject to an applied load.^[10]

Stress–strain relations[edit]

Basic static response of a specimen under tension

• Elasticity is the ability of a material to return to its previous shape after stress is released. In many materials, the relation between applied stress is directly proportional to the resulting strain (up to a certain limit), and a graph representing those two quantities is a straight line.

The slope of this line is known as Young's modulus, or the "modulus of elasticity." The modulus of elasticity can be used to determine the stress–strain relationship in the linear-elastic portion of the stress–strain curve. The linear-elastic region is either below the yield point, or if a yield point is not easily identified on the stress–strain plot it is defined to be between 0 and 0.2% strain, and is defined as the region of strain in which no yielding (permanent deformation) occurs.^[11]

• Plasticity or plastic deformation is the opposite of elastic deformation and is defined as unrecoverable strain. Plastic deformation is retained after the release of the applied stress. Most materials in the linear-elastic category are usually capable of plastic deformation. Brittle materials, like ceramics, do not experience any plastic deformation and will fracture under relatively low stress. Materials such as metals usually experience a small amount of plastic deformation before failure while ductile metals such as copper and lead or polymers will plasticly deform much more.

Consider the difference between a carrot and chewed bubble gum. The carrot will stretch very little before breaking. The chewed bubble gum, on the other hand, will plastically deform enormously before finally breaking.

Design terms[edit]

Ultimate strength is an attribute related to a material, rather than just a specific specimen made of the material, and as such it is quoted as the force per unit of cross section area (N/m²). The ultimate strength is the maximum stress that a material can withstand before it breaks or weakens.^[12] For example, the ultimate tensile strength (UTS) of AISI 1018 Steel is 440 MN/m². In general, the SI unit of stress is the pascal, where 1 Pa = 1 N/m². In Imperial units, the unit of stress is given as lbf/in² or pounds-force per square inch. This unit is often abbreviated as psi. One thousand psi is abbreviated ksi.

A Factor of safety is a design criteria that an engineered component or structure must achieve. , where FS: the factor of safety, R: The applied stress, and UTS: ultimate stress (psi or N/m²) ^[13]

Margin of Safety is also sometimes used to as design criteria. It is defined MS = Failure Load/(Factor of Safety * Predicted Load) - 1

For example to achieve a factor of safety of 4, the allowable stress in an AISI 1018 steel component can be calculated to be  = 440/4 = 110 MPa, or  = 110×10⁶ N/m². Such allowable stresses are also known as "design stresses" or "working stresses."

Design stresses that have been determined from the ultimate or yield point values of the materials give safe and reliable results only for the case of static loading. Many machine parts fail when subjected to a non steady and continuously varying loads even though the developed stresses are below the yield point. Such failures are called fatigue failure. The failure is by a fracture that appears to be brittle with little or no visible evidence of yielding. However, when the stress is kept below "fatigue stress" or "endurance limit stress", the part will endure indefinitely. A purely reversing or cyclic stress is one that alternates between equal positive and negative peak stresses during each cycle of operation. In a purely cyclic stress, the average stress is zero. When a part is subjected to a cyclic stress, also known as stress range (Sr), it has been observed that the failure of the part occurs after a number of stress reversals (N) even if the magnitude of the stress range is below the material’s yield strength. Generally, higher the range stress, the fewer the number of reversals needed for failure.

Failure theories[edit]

There are four important failure theories: maximum shear stress theory, maximum normal stress theory, maximum strain energy theory, and maximum distortion energy theory. Out of these four theories of failure, the maximum normal stress theory is only applicable for brittle materials, and the remaining three theories are applicable for ductile materials. Of the latter three, the distortion energy theory provides most accurate results in majority of the stress conditions. The strain energy theory needs the value of Poisson’s ratio of the part material, which is often not readily available. The maximum shear stress theory is conservative. For simple unidirectional normal stresses all theories are equivalent, which means all theories will give the same result.

• Maximum Shear stress Theory- This theory postulates that failure will occur if the magnitude of the maximum shear stress in the part exceeds the shear strength of the material determined from uniaxial testing.

• Maximum normal stress theory - This theory postulates that failure will occur if the maximum normal stress in the part exceeds the ultimate tensile stress of the material as determined from uniaxial testing. This theory deals with brittle materials only. The maximum tensile stress should be less than or equal to ultimate tensile stress divided by factor of safety. The magnitude of the maximum compressive stress should be less than ultimate compressive stress divided by factor of safety.

• Maximum strain energy theory - This theory postulates that failure will occur when the strain energy per unit volume due to the applied stresses in a part equals the strain energy per unit volume at the yield point in uniaxial testing.

• Maximum distortion energy theory - This theory is also known as shear energy theory or von Mises-Hencky theory. This theory postulates that failure will occur when the distortion energy per unit volume due to the applied stresses in a part equals the distortion energy per unit volume at the yield point in uniaxial testing. The total elastic energy due to strain can be divided into two parts: one part causes change in volume, and the other part causes change in shape. Distortion energy is the amount of energy that is needed to change the shape.

• Fracture mechanics was established by Alan Arnold Griffith and George Rankine Irwin. This important theory is also known as numeric conversion of toughness of material in the case of crack existence.
• Fractology was proposed by Takeo Yokobori because each fracure laws including creep rupture criterion must be combined nonlinially.

Microstructure[edit]

A material's strength is dependent on its microstructure. The engineering processes to which a material is subjected can alter this microstructure. The variety ofstrengthening mechanisms that alter the strength of a material includes work hardening, solid solution strengthening, precipitation hardening and grain boundary strengthening and can be quantitatively and qualitatively explained. Strengthening mechanisms are accompanied by the caveat that some other mechanical properties of the material may degenerate in an attempt to make the material stronger. For example, in grain boundary strengthening, although yield strength is maximized with decreasing grain size, ultimately, very small grain sizes make the material brittle. In general, the yield strength of a material is an adequate indicator of the material's mechanical strength. Considered in tandem with the fact that the yield strength is the parameter that predicts plastic deformation in the material, one can make informed decisions on how to increase the strength of a material depending its microstructural properties and the desired end effect. Strength is expressed in terms of the limiting values of the compressive stress, tensile stress, and shear stresses that would cause failure. The effects of dynamic loading are probably the most important practical consideration of the strength of materials, especially the problem of fatigue. Repeated loading often initiates brittle cracks, which grow until failure occurs. The cracks always start at stress concentrations, especially changes in cross-section of the product, near holes and corners at nominal stress levels far lower than those quoted for the strength of the material.

Brain 'still active during sleep'

The brain is still active while we are asleep, say scientists, who found people were able to classify words during their slumber.

Researchers from Cambridge and Paris introduced participants to a word test while awake and found they continued to respond correctly while asleep.

The sleeping brain can perform complex tasks, particularly if the task is automated, the study says.

Further research will now focus on how to take advantage of our sleeping time.

Writing in the journal Current Biology, the research team set out to study the brain's behaviour while awake and during sleep.

Using an electroencephalogram (EEG), they recorded the brain activity of participants while they were asked to classify spoken words as either animals or objects by pressing a button.

Unconscious behaviour

Participants were asked to press a button in their right hand for animals and in their left hand for objects.

This allowed researchers to track the responses and map each word category to a specific movement in the brain.

Then participants were asked to lie down in a darkened room with their eyes closed and continue the word classification task as they drifted off to sleep.

Once asleep, a new list of words was tested on participants to ensure that the brain had to work out the meaning of the words before classifying them using the buttons.

Their brain activity showed they continued to respond accurately, the researchers said, although it happened more slowly.

At the time, the participants were completely motionless and unaware.

it was possible for people to perform calculations on simple equations while falling asleep and then continue to identify those calculations as right or wrong during a snooze.

Any task that could become automated could be maintained during sleep, he said. But tasks that cannot be automated would stop as sleep took over.

Their research could lead to further studies on the processing capacity of our sleeping brains, the study said.

Depression on children. ....

Being bullied regularly by a sibling could put children at risk of depression when they are older.

Around 7,000 children aged 12 were asked if they had experienced a sibling saying hurtful things, hitting, ignoring or lying about them.

The children were followed up at 18 and asked about their mental health.

A charity said parents should deal with sibling rivalry before it escalates.

Previous research has suggested that victims of peer bullying can be more susceptible to depression, anxiety and self-harm.

This study claims to be the first to examine bullying by brothers or sisters during childhood for the same psychiatric problems in early

'Twice as likely'

Most children said they had not experienced bullying. Of these, at 18, 6.4% had depression scores in the clinically significant range, 9.3% experienced anxiety and 7.6% had self-harmed in the previous year.

The 786 children who said they had been bullied by a sibling several times a week were found to be twice as likely to have depression, self-harm and anxiety as the other children.

In this group, depression was reported by 12.3%, self-harm by 14%, and 16% of them reported anxiety.

Girls were slightly more likely to be victims of sibling bullying than boys, particularly in families where there were three or more children.

Older brothers were often found to be responsible.

On average, victims said that sibling bullying had started at the age of eight, the study said.

Suicide every 40 seconds

Somebody dies by taking their own life every 40 seconds, according to a significant report by the World Health Organization (WHO).

It said suicide was a "major public health problem" that was too often shrouded in taboo.

The WHO wants to reduce the rate of suicide by 10% by 2020, but warned that just 28 countries have a national suicide prevention strategy.

Campaigners said there needed to be more education in schools.

The WHO analysed 10 years of research and data on suicide from around the world.

It concluded:

• Around 800,000 people kill themselves every year

• It was the second leading cause of death in young people, aged 15 to 29

• Those over 70 were the most likely to take their own lives

• Three-quarters of these deaths were in low and middle income countries

• In richer countries, three times as many men as women die by suicide

It said limiting access to firearms and toxic chemicals was shown to reduce rates of suicide.

And that introducing a national strategy for reducing suicides was effective, yet had been developed in only a minority of coun

India's Kerala to ban alcohol sales ; The government plans to enforce total prohibition in 10 years

Authorities in the southern Indian state of Kerala have outlined plans to ban the sale and consumption of alcohol to tackle the state's drink problem.

The first phase of the ban would see more than 700 bars and as well as some shops selling alcohol shut down, with more alcohol-free days introduced.

The government aims to enforce total prohibition in 10 years.

Kerala has India's highest per capita alcohol consumption at more than eight litres per person yearly.

Doctors and activists have highlighted rising alcohol abuse, blaming it for many road accidents and even marital breakdown. They say hospitals and rehabilitation centres are packed with patients suffering from alcohol-related diseases.

Chief Minister Oomnen Chandy said the Congress-led government planned to make Kerala "liquor free" with a series of proposed measures in the coming months:

• A total of 730 bars serving alcohol will be shut.

• Sundays will be added to existing alcohol-free days on the first day of every month

• Only luxury hotels will be allowed to serve alcohol from next year.

• 10% of the 338 liquor shops owned by a state-run monopoly will be shut every year.

"The state should be prepared to accept total prohibition within this period [of 10 years]," he said.

Correspondents say businesses are worried that the proposed ban may hit tourism in the state. Kerala is the state which attracts the highest number of tourists in India.

Nor is it clear how the government plans to recover lost earnings from alcohol sales, which by one estimate accounts for more than 20% of revenues in the state's annual budget

INDIA TO PROVIDE FOUR FREE VACCINES

every year
India will provide four new vaccines free of cost as part of a programme to reduce child mortality, Prime Minister Narendra Modi has said.

They include one for rotavirus, which kills thousands of children a year.

The disease causes dehydration and severe diarrhoea. It spreads via contaminated hands and surfaces, and is common in Asia and Africa.

The move brings to 13 the number of free vaccines provided against life threatening diseases.