stop bollard safety road device

8/12/2019 Stop Bollard Safety Road Device

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FINITE ELEMENT METHOD

Omni Stop Bollard Safety Road Device


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Table of Contents1 Introduction ........................................................................................................................................... 1

1.1 Materials ....................................................................................................................................... 2

1.1.1 Steel ....................................................................................................................................... 2

1.1.2 Concrete ................................................................................................................................ 3

1.1.3 Wood ..................................................................................................................................... 4

2 Literature Review .................................................................................................................................. 5

2.1 Definitions ..................................................................................................................................... 5

2.2 Hazards ......................................................................................................................................... 6

2.3 Material ......................................................................................................................................... 7

3 Finite Element Modelling Methodology ............................................................................................... 8

4 Result .................................................................................................................................................. 12

4.1 Steel............................................................................................................................................. 12

4.1.1 Single element ..................................................................................................................... 12

4.1.2 Sixteen elements ................................................................................................................. 12

4.2 Concrete ...................................................................................................................................... 13

4.2.1 Single element ..................................................................................................................... 13


4.3 Wood ........................................................................................................................................... 14

4.3.1 Single element ..................................................................................................................... 14


5 Discussion ........................................................................................................................................... 15

5.1 Single Element Stop Bollard ....................................................................................................... 15

5.2 Sixteen Elements Stops Ballard .................................................................................................. 15

6 Conclusion .......................................................................................................................................... 16

References: .................................................................................................................................................. 17


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Omni Stop Bollard Safety Road Device

1 Introduction

Safe road device are design about providing a road environment which ensures vehicle speeds will be

within the human tolerances for serious injury and death wherever conflict points exist. There many types

of safety road device such as barrier, corner barrier, crash barrier, bumper, omni stop bollard and more.

Furthermore, the highest possible degree of safety shall be ensured when transporting goods by road. It is

of vital importance to monitor and validate the road transportation safety, including comprehensive

checks on drivers, vehicles and safety processes.

The basic strategy of a safe system approach is to ensure that in the event of a crash, the impact

energies remain below the threshold likely to produce either death or serious injury. This threshold will

vary from crash scenario to crash scenario, depending upon the level of protection offered to the road

users involved. For example, the chances of survival for an unprotected pedestrian hit by a vehicle

diminish rapidly at speeds greater than 30 km/h, whereas for a properly restrained motor vehicle occupant

the critical impact speed is 50 km/h (for side impact crashes) and 70 km/h (for head-on crashes).

For our finite element method project we choose Omni Stop Bollard which is one type of road

safety device. The Omni Stop Bollard is a fully tested system capable of stopping a passenger car at 60

km/h from entering an area occupied by pedestrians or diners. At the point of impact of a vehicle, the

Omni Stop's energy absorbing cartridge which is at the base of the steel bollard absorbs the energy and

safely decelerated the vehicle at a level that is safe for the occupant.

Figure 1: Omni stop bollard


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1.1 Materials

In our project we selected material as our research to define a different material of road safety device. We

choose three materials to find the material different such as steel, concrete and wood. All these materialare suitable to make a road safety device.

1.1.1 Steel

Steel is an alloy of iron and a small amount of carbon. Carbon is the primary alloying element, and its

content in the steel is between 0.002% and 2.1% by weight. Too little carbon content leaves (pure) iron

quite soft, ductile, and weak.

Iron and steel are used widely in the construction of roads, railways, other infrastructure,

appliances, and buildings. Most large modern structures, such as stadiums and skyscrapers, bridges, and

airports, are supported by a steel skeleton. Even those with a concrete structure employ steel for

reinforcing. In addition, it sees widespread use in major appliances and cars. Despite growth in usage of

aluminum, it is still the main material for car bodies. Steel is used in a variety of other construction

materials, such as bolts, nails, and screws.

Other common applications include ship building, pipelines, mining, offshore construction,

aerospace, white goods (e.g. washing machines), heavy equipment such as bulldozers, office furniture,steel wool, tools, and amour in the form of personal vests or vehicle amour (better known as rolled

homogeneous amour in this role). Steel was the metal of choice for sculptor and a frequent choice for

sculpture by many other modern sculptors.

Figure 2: Cylinder steel


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1.1.2 Concrete

Concrete is a composite material composed of coarse granular material (the aggregate or filler) embedded

in a hard matrix of material (the cement or binder) that fills the space among the aggregate particles andglues them together. Concrete is widely used for making architectural structures, foundations, brick /

block walls, pavements, bridges / overpasses, highways, runways, parking structures, dams, pools /

reservoirs, pipes, footings for gates, fences and poles and even boats.

There are many types of concrete available, created by varying the proportions of the main

ingredients below. In this way or by substitution for the cementations and aggregate phases, the finished

product can be tailored to its application with varying strength, density, or chemical and thermal

resistance properties.

Concrete is strong in compression, as the aggregate efficiently carries the compression load.

However, it is weak in tension as the cement holding the aggregate in place can crack, allowing the

structure to fail. Reinforced concrete adds steel reinforcing bars, steel fibers, glass fiber, or plastic fiber to

carry tensile loads.

Figure 3: Cylinder concrete


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1.1.3 Wood

Wood is a hard, fibrous structural tissue found in the stems and roots of trees and other woody plants. It

has been used for thousands of years for both fuel and as a construction material. It is an organic material,a natural composite of cellulose fibers (which are strong in tension) embedded in a matrix of lignin which

resists compression.

Wood is sometimes defined as only the secondary xylem in the stems of trees, or it is defined

more broadly to include the same type of tissue elsewhere such as in tree roots or in other plants such as

shrubs. In a living tree it performs a support function, enabling woody plants to grow large or to stand up

by them. It also mediates the transfer of water and nutrients to the leaves and other growing tissues. Wood

may also refer to other plant materials with comparable properties, and to material engineered from wood,

or wood chips or fiber.

Figure 4: Trees trunk


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2 Literature Review

The vehicle restraint systems and roadside areas standard provide a general framework for the design and

standard of roads, and apply to all public roads. Safety measures can be divided into two approaches. Thefirst approach is to reduce the probability of a vehicle collision. This approach is the one most commonly

used and can be illustrated both historically and technically. The second approach is to reduce the severity

of the impact when the utility is struck by an errant vehicle. These two approaches may be considered

singly or in combination as dictated by the specific side condition. The purpose of safety barriers is

primarily to reduce as much as possible the extent of damage and injuries in case of incidents where

vehicles leave the road. Safety barriers are installed to:

1. Prevent driving off the road where there are high, steep embankments, deep ditches,water and other.

2. Prevent collisions between traffic in opposite directions3. Protect road users and other who are on or near the road against vehicles.4. Protect special installations near the road, example railway.5. Prevent damage to road structure which could give rise to very serious consequential

damage if impacted example bridges.

6. Prevent errant vehicles from falling down onto roads, railways or into rivers passingunder the road.

2.1 Definitions:

TERMS DEFINATIONS

Rigid safety barriers Safety barriers that do not suffer large permanent deformation on

impact. The impact energy is partly absorbed as deformation of the

vehicle and as friction between the vehicle and the safety barrier, and in

some cases by lifting the vehicle up in a controlled manner.

Safety Barrier A device that shall prevent vehicles from leaving the road.


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2.2 Hazards

Hazards may be divided into four main categories:

Fixed roadside obstaclesthat will pose a serious risk of injury or damage on impact. This maybe roadside obstacles that are part of the roads construction (protruding culverts, abutments and

piers), roadside furniture (lighting and sign posts), and element in the terrain outside the body of

the road or other structures.

Dangerous side slopes that have a form that will overturn or abruptly stop a vehicle if it drivesoff the road.

Other road users, for example pedestrians and cyclists or motorists travelling in the oppositedirection who will be exposed to serious risk of injury or damage if a vehicle drives off the road.

Special installations in the roadside area, such as parallel and crossing railway or metro tracks,fuel tanks, water reservoirs and other. That, in the case of a vehicle driving off the road, may

result in secondary accidents with very serious and extensive consequential injury and damage.

Safety barriers shall be used at precipices, embankments, bridges, retaining walls and others. If their

height exceeds the minimum values.

Fig 2.3: This movement will occur if there are no safety devices.

Fig 2.4: example application of roadside safety devices.


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2.3 Material:

In our project we used making Road and bridge safety barriers must be delivered in material quality they

have been tested for. It is not permitted to use material of a higher or lower quality than that used in thefull scale test or simulation. Standard safety barriers, reference is made to the barrier guide.

Steel Concrete Wood

Material Description of material.

Steel

Iron and steel are used widely in the construction of roads, railways, and other

infrastructure. Steel is an alloy of iron and a small amount of carbon Too little

carbon content leaves (pure) iron quite soft, ductile, and weak.

E = 200e9

v= 0.3

Concrete Concrete is a composite material composed of coarse granular material. Concrete

is strong in compression, as the aggregate efficiently carries the compression load.

E = 17e9

v= 0.2

Wood Wood material used in safety barriers shall comply with the requirement set by themanufacturer. It must be impregnated and possible treated so that the prescribe

lifespan is achieved.

E = 13e9

v= 0.07


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3 Finite Element Modelling Methodology

For project analysis, we use software LISA 7.7.0 to compare the difference material for these safety road

devices. As we mention before, this project consists of three types of materials. Each material has theirrespective Youngs Modulus and Poissons ratio value which is:

Table 3.1: Young Modulus and poison ratio for each material

Material Youngs Modulus (GPa) Poissons Ratio

Steel 200 0.3

Concrete 17 0.2

Wood 13 0.07

For safety road device, we consider all shape is cylindrical. So, all this analysis for this three

difference materials will using 3-D dimensions. By using LISA 7.7.0 software, this cylindrical shape can

be formed at Circular bar. To see which material are more resistant when get impact, we use same

diameter for all materials which is 0.15 m.

Figure 3.1: Cylindrical Shape

Set coordinate for Node 1 and Node 2. Node 1 with coordinate (0, 0, 0), and Node 2 with

coordinate (0, 1.45, 0).


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Figure 3.2: Coordinate Node 1 and Node 2

Add Element for Node 1 and Node 2 to make a circular bar as a cylindrical shape.

Figure 3.3: Toggle Hidden Line and Toggle Wireframe

Select Node 1 and fixed to the floor. Constraints the Node 1 by add displx, disply and displz with

0. After that, add Node 1 and 2 with force. Add forcex with 500 X 103N.

Figure 3.4: Element 1 with constraint and loads


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Solve the analysis to get the result for single element for three difference materials which is Steel,

Concrete and Wood. The figure below show the result for Steel after solving the analysis.

Figure 3.5: Result for 1 element (example: Steel)

After finish analysis for a single element, we use Refine to divide the cylindrical segment from

one element to more elements. So, we refine Element 1 by 4 times to get much Node and Element.

Constraints the Node 1 by add displx, disply and displz with 0. After that, add all Node with force. Add

forcex with 500 X 103 N.

Figure 3.6: Element 1 after refine with constraint and loads


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Figure 3.7: Result for refine element (example: Steel)

After finish the analysis using steel material for single element and refine element, repeat the

same step to analysis the impact to the safety road devices by using other two materials which is concrete

and wood. Change the Youngs Modulus and Poissons ratio value.


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4 Result4.1 SteelResult for steel with Youngs Modulus of 200GPa and Poisson ratio of 0.3.

4.1.1 Single element

For a steel single element, the highest displacement magnitude was 9.633E+13which occur at node 2.

4.1.2 Sixteen elements

For a steel sixteen elements, the highest displacement magnitude was 9.71E+13which occur at node 2.


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4.2 ConcreteResult for concrete with Youngs Modulus of 17GPa and poison Ratio of 0.2.


For a concrete single element, the highest displacement magnitude was 3.96E+15 which occur at node 2.


For a concrete sixteen elements, the highest displacement magnitude was 6.57E+15 which occur at node

2.


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4.3 WoodResult for wood with Youngs Modulus of13GPa and Poisson ratio of 0.07.


For a wood single element, the highest displacement magnitude was 3.23E+15 which occur at node 2.


For a woodsixteen elements, the highest displacement magnitude was 3.32E+15 which occur at node 2.


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5 Discussion

All of three examples of stop bollards have been simulated in LISA to produce the significant result to

compare for. Each of the material of stop bollard have been subjected to similar force and been constraintat the similar point with dimension for all three stop bollard. As a result, all three bollards presented a

significant deformation magnitude value. Concretes bollard was the one with the highest displacement

magnitude followed by wood and steel.

5.1 Single Element Stop Bollard

In the single element stop bollard, the displacement magnitude between the concrete and wood was

actually not so significant. The concrete was the worse with 3.96E+15 while the wood was 3.23+15. The

best stop bollard with least displacement is steel with 9.62E+13. Steel does not displace as much as the

other two materials mainly because of its mechanical properties. Among three of those material, steel was

the only one that pose a ductile criteria and have the highest value of Youngs Modulus. Young Modulus

is the resistance of material to deform under the given load. While both concrete and wood pose the

lowest Young Modulus, it tends to deform easily. Another factor that drive the value for displacement in

this study was the number of element that been study under the given structure. As for single element in

the single structure, the load cannot distribute evenly to the whole big structure of single element. Thus

the result would be a bit higher that refine structure.

5.2 Sixteen Elements Stops Ballard

For the refine structure with the sixteen elements in single structure, the value of displacement magnitude

was proved to be lower than the single element structure. For steel, the highest magnitude displacement

value was 9.71E+10 compare to 9.62+13 in single element structure. For the concrete, the value of

magnitude displacement was significantly decreased with 6.57E+12 compare to3.96E+15. While the

wood also shows the exact pattern with 3.32E+12 compare to 3.23+15. From the structure itself, the

number of element in one structure body play an important role to add the density of structure. With large

number of element, the load can evenly distribute along the structure.


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6 Conclusion

As a conclusion for this study, the steel stop bollard produces the lowest displacement magnitude under

the given load. As a safety road device, steel stop bollard have the right criteria which is less deform

under the force. Another important thing that needs to conclude is the more the element in the structuralbody, the precise the result will be. This is because, with large number element under the studys structure

body will produce the greater resolution if it body. At the same time, the density of structure also

increases. As for comparison, the structure with single element wills only focuses on both end of the

structure as the structure was its only element. While in the structure with two elements or more, the focus

point now will evenly distribute to each of element in the structure, thus the focus point will not be bias

only at both end like in single element. That why in the multiple elements structure, the result value seems

to be smaller compare to single element structure.


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References:

1. StatensVegvesen,( 2011), Vehicle Restraint System, Norwegian Public Roads AdministrationManual.

2. Liu, Y. and Glass, G.(2013), "Effects of Mesh Density on Finite Element Analysis," SAE TechnicalPaper 2013-01-1375, 2013, doi:10.4271/2013-01-1375.

3. RuiTuo, C. F. JeffWu, and Dan Yu. (2012), Modeling of Computer Experiments withDifferent MeshDensities.

4. The Engineering Toolbox, Impact Force. Reached on 18/12/2013 athttp://www.engineeringtoolbox.com/impact-force-d_1780.html

5. Omni stop bollardshttp://www.saferoads.com.au/products-services/crash-cushions/omni-stop-bollards

6. Barrier guard with fencehttp://www.highwaycare.co.uk/product_info/60/barrierguard-with-fence

7. Steel material propertieshttp://www.steelconstruction.info/Steel_material_properties

8. Steelhttp://en.wikipedia.org/wiki/Steel

9. Concretehttp://en.wikipedia.org/wiki/Concrete

10.Cements and concrete basicshttp://www.cement.org/basics/concretebasics_concretebasics.asp

11.Woodhttp://en.wikipedia.org/wiki/Wood

stop bollard safety road device

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