Engineering Design Practice - Assignment Example

Student Name: Tutor: Title: Engineering Design Practice Course: Question one Restrained beam test It entailed heating a solitary 305 × 165Ub40 beam and also heating the slab around it. Its major aim was to find out the consequences of restraint from a big region of neighboring cool structure. This includes floor slabs on the performance of the heated structure Primary plane frame Also called the British Steel Plane Frame Test. It involves the beams and columns that support the floor across its entire width. The maximum temperature found was 808 degrees Celsius for the steel beam and 385 degrees Celsius for the concrete slab. The top coating of the slab attained 95 degrees Celsius. British Steel Corner Bay Test The test was contacted on a corner bay 9.98m in width and 7.57m in length. The beams and columns were enveloped with ceramic insulation while the remaining elements were not insulated. A maximum of 1028 degrees Celsius was recorded. BRE Corner Bay Test Is similar to the British Steel corner test. The difference is the restriction of vertical descending movement of the edge beams by wind posts. Every structural member was not insulated in the compartment except the steel columns. The highest temperature recorded for the internal beam was 842 degrees Celsius while the edge beam had a temperature of 590 degrees Celsius. The concrete slabs and columns measured 285 and 150 degrees Celsius respectively. Thermocouples were used in the temperature measurement (Keltner et al, 1998). Large Compartment test This test covers the entire building width. Insulation of the columns covered their entire height and connections while the beams were not insulated. The atmospheric and steelwork temperatures recorded were 763 degrees Celsius and 691 degrees Celsius in that order. The lower layer of the concrete block had its highest average temperature at 260 degrees Celsius. Demonstration Test This test was planned to represent a normal office fire. Both the inside columns and the inside parts of perimeter columns were completely insulated .The beams and their connections were however left unprotected. Question 2 Due to the differences in fire situations, tests carried out cannot be 100 percent replicas of fire situations. The changing conditions during a fire also provide a hurdle in the construction of either a small scale or full scale model for a tire test. It is therefore impractical to design a test representing all conditions during a fire (Cote and Bugbee, 1988). Well defined similarities between a small scale model and a large scale model are needed for them to be valuable in the analysis of a real fire. The Froude number is usually utilized in classifying the types of fire. Fr=U2/gL where U = gas velocity, g=gravitational acceleration, L=dimension. The Reynolds number and Richardson number are also used. For a perfect correlation between a small sale fire, a large scale experiment, these numbers should be the same for each scenario but as this is impossible only consistency in the Froude number is used. Question 3 Fire safety includes the safety of both property and people. Fire safety objectives will therefore strive to minimize the occurrence of injury or death to residents of the building or other people who may be involved with the fire. Fire safety also tries to reduce the chances of property getting destroyed. This includes the contents of and the building itself. The tactics available to the fire safety designer will include: Prevention: making sure fires don’t start in the building Communication: makes sure that in case of a fire, the residents are informed and fire fighting systems activated. Evacuation/escape: ensuring that the residents and others in the vicinity move to safe areas Containment: ensuring that the fire is minimized to the smallest region possible where it can be safely extinguished. Extinguishment: makes sure the fire can be put out with very little damage done to the premises. Fire engineering is the use of principles of science and engineering, rules and professional judgment in the protection of people, property and the environment from fire and smoke. Some of the merits of fire engineering include: It enables fire prevention in buildings and outdoors Fire engineering makes control and suppression of fire possible It is applied in the evacuation of people from burning buildings It is applied in managing and controlling smoke and the resultant effects Fire engineering is utilized in designing and planning of buildings It is not only confined to buildings as its put to use in preventing and/or managing wildfires (Stollard and Abrahams, 1999). Question 4 They include: Peak and average Heat release rate: is the rate at which heat is released in a combustion process inside the flame. Smoke density: is the amount of light obscuration created by smoke from a fire in given conditions. Soot yield: it is mass of soot per available mass of fuel Mass loss rate: is the mass of fuel vaporized (but not necessarily) burned per unit time Other parameters that can be measured using the cone calorimeter are: Yields of CO2, Time to ignition, Time of sustained flaming, Effective heat of combustion, Heat release response Question 5 Positive pressure ventilation is a fire fighting technique where a fan is used to move air from outside the structure and forcefully moving it into the interior. This causes an increase in air pressure in the interior resulting in the expulsion of heated gasses and smoke through any available passageway. Question 6 The flash point of a fuel is the lowest temperature at which sufficient fuel can evaporate in enough quantities to be ignitable. Question 7 The limiting oxygen index test is a test for determining the ignitability resistance of materials. This test computes the least oxygen concentration that is required to sustain combustion of a particular material. Its main disadvantage is that there is no feedback to the specimen as the majority of energy is carried away by convection Question 8 The LOI is inversely proportional to flammability. This is to say, flammability reduces with increase in LOI. For example, PVC has a limiting oxygen index of 23-43 while nylon 6 has a LOI of 15-16. Question 9 Piloted ignition is the ignition of flammable vapor or gas accidentally after coming into contact with a high energy source. This can be a flame or a spark. Auto ignition on the other hand is the initiation of ignition by chemical process inbuilt in the material at a particular fuel concentration and temperature. Question 10 Fire tests are important to determine the performance capability of a material as set out by government or building codes. Those products that pass the fire test are issued with a certificate. Question 11 Explain what causes a “V” pattern during a fire in a compartment. When hot gasses from a fire go up in normal convection mode, the gasses are likely to spread out while they rise forming a V. Question 12 Define the term “heat release rate”. Include diagrams showing heat release rate for thermally thin and thermally thick, charring and non-charring materials. Heat release rate is the total amount of heat discharged by the gas phase of combustion of a unit mass of fuel discharged by pyrolysis per unit time and per unit area of the burning surface. HRR=1dQ/Sdt= ρδ (1Dq/mdt)=ρδQC Where, Q=amount of heat, m=mass, t= time, S=area, ρ=average density, δ=breadth of the mesophase Question 13 There are five main factors which will affect the development of fire growth within a compartment. They can be divided into two categories: those that are concerned with the compartment itself and those which are concerned with the fuel. Identify these factors. Those factors concerned with the department are: The shape and size of the compartment The amount of ventilation available in the compartment The distribution and type of ventilation Type of materials the wall, roof and floor are made out of Those factors concerned with the fuel include: Amount, type and distribution of fuel within the compartment Question 14 Test 1 2 3 4 5 6 7 8 9 10 Heat Release Rate @ 25.00kW/m2 44.80 42.15 42.97 43.60 43.88 44.80 42.79 45.10 41.62 43.74 The range=3.48 The mean=sum of HRR/no. of samples=43.545 Standard deviation=1.16779 Standard uncertainty= standard deviation/square root of no. of units=1.16779/3.1623=0.369 Uncertainty range=43.176 to 43.914 Question 15 Test 1 Test 2 Test 3 Test 4 Test 5 Test 6 Test 7 Test 8 Number of Drops 2 6 10 12 14 16 18 20 Height attained by lid (cm) 0 20 40 80 120 150 110 90 The results show there was an increase in the height attained by the lead until a saturation point was reached where increase in the amount of fuel had no impact. PART B Question 1 Maximum recommended size for: (a) A single storey shop with sprinkler protection.2000m2 (b) A single storey industrial unit.4000m2 Question 2 Maximum size of an unprotected are depends upon the limiting distance and is given by 0.24[(2*LD)-1.2]2 if LD is less than 2 Question 3 a. a fire fighting shaft with a fire fighting lift are both recommended b. both the shaft and the lift are recommended Question 4 A 30m high sprinkler protected residential building: sixty minutes A single storey shop with sprinkler protection: 30 minutes Question 5 A student’s union building: from Table D1, the purpose group will be 2(b)(other ) A department store: from table D1, a departmental store belongs to group 4 (shop and commercial) A factory. From the table, a factory will fall under group 6 (industrial) Question 6 A normal hazard storage facility Single direction 25m More than 1 direction 45m. A place of special fire hazard Single direction 9m More than one direction 18m The bedroom of an apartment Single direction 9m More than 1 direction 18m A lecture theatre with fixed seating in rows Single direction 15m More than one direction 32 m Shop floor Single direction 18m More than one direction 45m Plant room that exits through the accommodation within a building Single direction 18m More than 1 direction 45 m Question 7 According to Table 3 of ADB, what is the recommended minimum number of escape routes from a storey with: Number of people Minimum number of escape routes 10 people. 1 100 people 2 200 people 2 500 people 2 Question 8 Number of people Minimum exit width(mm) 219 1050 61 850 10 750 500 2500 Question 9 75 persons The ground floor doesn’t have stairs, therefore 75people ×3 storey=225 P=200w+ 50[w-0.3][n-1] P =225=200w+50[w-0.3][3-1] 225=200w + [50w-15]2 225=200w +100w-30 W= 0.85 meters 130 persons W=[390+45-15]/150+ 50n =1.4 meters Question 10 A building with five above ground floors is served by three escape stairs with lobby protection. Using Table 7 of ADB, what is the minimum width of the escape stairs if each floor accommodates? (c) 155 persons 155×4=620 All the stairs are used (due to the presence of a protected lobby) P =620/3=207 W=p+15n-15/(150+50n)=207+60-15/(150+200)=0.72m (d) 230 persons 230×4=920 920/3=307 W=307+60-15/(150+200) =1m Question 11 W= ((N/2.5)+60S))/80 For w=0.85m, required final exit= ((325/2.5)+(60×0.85)/80=2.26meters For the 1.4m stairwell, required exit= ((490/2.5) + (60×1.4)/80=3.5 meters For question 10, For w=0.72, exit= ((307/2.5) + (60×0.72)/80=2.075 For w=1m, exit= ((407/2.5) + (60)/80=2.785 meters Question 12 According to Table C1, what floor space factors would be appropriate in the following areas? (e) An office 6.0 m2 /person (f) A bar 0.3 m2/person (g) A shop 2.0m2/person (h) A students union 0.3m2/person Question 13 For a square room, 40m by 40m, calculate the number of occupants using the floor space factors obtained in Question 12. In each case what is the minimum number of exits required and how wide should each exit be as a minimum. Floor area=1600m2 For the office occupant load=1600/6=267 occupants U=N/ (40×T) Where, U-units of exits, N= number of occupants =267/ (40×3) =2.225 Number of exits =U/4+1=0.45.therefore one exit will be provided. For the bar, 1600/0.3=5333 occupants U=5333/120=44.4 44.4/4+1 Number of exits=8.88 9 exits will be provided For the shop, 1600/2=800 occupants U=800/120=6.67 Number of exits=6.67/4+1=1.3, therefore 1 exit will be provided. Student union, 1600/0.3=5333 occupants Question 14 Life safety is defined as the concern for human life and well being of residents. It is the standards and measures in design and construction that are put in place to protect human life from fire, fumes and smoke. Property protections are the procedures put in place to prevent damage by fire Fire resistance is the ability of a material to be unyielding to fire so that for a definite amount of time and temperature, no structural failure occurs. Cavity barriers are constructions specifically provided for the closure of concealed spaces and prevent their penetration by fire and smoke. Question 15 Estimates of internal room size 5 by 5 a. Travel distances from each room and each floor, 10-2.5=7.5m maximum b. Occupancy load, Area of the office =2(25×5) =250m2 With a workspace factor of 6 Occupancy load=250/6=42 occupants c. Purpose group, From table D1 the Purpose group is 3 (office) d. Exit and final exit widths, U=N/(40×T), where u= number of units needed, N=occupants, 40= rate of flow, T=flow time(3 minutes for class A,2.5 Minutes for class B and 2 Minutes for class C) =42/ (40×3) =0.35=0.4 units ≤1 therefore the width=750 mm wide e. Stair widths and For 42 occupant, stair width =42 times the capacity factor=42×7.62=320 mm of stairway width f. Classification of wall and ceiling linings. For this block of flats, they are in class 0(zero) References Cote, A. E. and Bugbee, P., 1988, Principles of fire protection. Massachusetts: Jones and Bartlett Keltner, N. R., Alvares, N. J. and Grayson, S. J., 1998, Very large scale fires. Baltimore: ASTM International Stollard, P. and Abrahams, J., 1999, Fire from first principles: a design guide to building fire safety. New York: Taylor &Francis Read More