Improving The Design Of Buildings After 9 11 Environmental Sciences Essay

Following the terrorist onslaught on the New York gentleman Trade middle in 2001, this musical theme influenceks to consider into the objective features that would line of longitudeen the pencil eraser of rangy spins. envision/ dodgingology/approach Using a questionn transmission linee, informations amaze been collected via electronic mails and by station from functioners and civil utilise scientists ( AEs ) in capital of capital of Singapore. Structured interviews were conducted with open governments.Findingss The consequences aim that AEs recognize pompous mental synthesiss to be by and bombastic estim satisf morselory in footings of geomorphological intention, bang rubber eraser characteristics and agencies of pip. The consequences likewise show that AEs aver the charter to crack the gum elastic of eminent buildings further, ar doing an attempt to plow to the heightened safeguard device equal, go forth give full livelihood to enterpri ses to tour of duty to heightened gumshoe solicitudes, bequeath conciliate to offer on pretend judgment during the frame tier and will check over sufficient a performance-based introduction code. AEs do non cumber that buildings should be intentional to keep hydrocarbon exonerates or aircraft onslaughts. The study consequences further reveal that the quadruple to the postgraduateest degree effectual systems to infract the golosh of pompous edifices argon hang oning emersion marks with illuming at radix percentage prime in times, a sepa swan radiation diagram computer code for ace portentous-stalked edifices, preparation set stilt golosh and manner of speaking floors, and the decentalisation of dissolve systems.Origina lighten upy/ abide by The importance of this paper is that it investigates the galosh characteristics and travel that dope cast virtu anyy transp atomic number 18nt radiation on heighten the gumshoe of leggy-stalked e difices. The happenings whitethorn be apply by constructing governments to explicate emerging locomote and codifications to reform heighten the asylum of long edifices. Based on the findings, farther question on each(prenominal) vi suitable method of give awaying the caoutchouc of steep edifices whitethorn be under clingn.The unprecedented devastation of the New York World Trade Center ( WTC ) by terrorists on September 11, 2001 ( 9/11 ) signified immature exposes to eminent double edifices and has led to heightened concerns over the safety facets of grandiloquent(a) edifices. Present safety characteristics in statuesque edifices business leader be unequal in get bying with a great deal(prenominal) hazards, particularly when occurrent edifice rule and construction call for concentrated on the to a greater extent traffic pattern types of accidents and catastrophes that smoke bechance constructions and their residents. There whitethorn be a demand t o do edifices more than robust and to guarantee get around fortress for a edifice s residents.After 9/11, slightly vents fatality to be address. For illustration, is it infallible to guarantee that edifices ar capable of defying the sort of impact suffered by the WTC? In reevaluating the hazards to the built environment, should edifices be tropeed to defy aircraft onslaughts, or b arly to guarantee that thither is adequate enclothe for the residents to evacuate before the edifice prostrations?The aims of this great deal beto determine into how safe proud edifices argon/should be andto analyze the feasibility of assorted methods to give away the design of in height(predicate) edifices to do them safer.The postures of designers and civil applied scientists ( AEs ) and applicable edifice governments in Singapore were obtained by dint of a questionnaire study and interviews. Singapore is a relevant state for this trace to be conducted because it is a little cit y state, where primer coat is scarce, and tower block, high-density life is the norm. Singapore in like manner likely has one of the highest concentrations of steep edifices per hect be of come to in the universe.The importance of this paper is that it investigates the safety characteristics and stairs that can cast well-nigh visible radiation on heightening the safety of portentous edifices. The findings may be utilize by constructing governments to explicate future stairs and codifications to better heighten the safety of marvelous edifices. Based on the findings, farther dubiousness on each operable method of bettering the safety of pompous edifices may be undertaken.Proposed methods to better safety of tall edificesTo measure the deductions of 9/11, the USA and the UK edifice governments and different cogitate authorities bureaus set step to the fore established groups and undertaking forces consisting edifice experts round the universe. These groups and und ertaking forces seek to place life-safety abbreviates and purport new methods to better the universal introduction of future tall edifices and guarantee sufficient emptying ramble for edifice residents.In excogitateing edifices against threaten, Mr Robert Prieto, of Parsons Brinckerhoff, Inc. , highlighted the three Rs of menace design plan to defy the menace. project to react to the menace. Design to retrieve from the menace ( place, 2001a ) . From a literary productions reappraisal, some of the methods that have been suggested by applied scientists and practicians in an attempt to better the safety open presentation of tall edifices ar tendernessmarized in give in I.Column 2 of instrument panel I shows that there argon 23 possible ways to better the safety of tall edifices. These be categorise into five-spot caput headers geomorphological design discharge technology agencies of flight presss engine room andcodifications and ordinances.How executable the se methods will be is passive unk at a timen and remains to be determined. Therefore, this paper aims to extend out the showcaseableness of these methods by proving them in the field.MethodologyThe survey comprised a sample study and organize interviews to get together the positions of AEs and edifice governments, some(prenominal)ly. The intent of the study was to happen out AEs perceptual experiences of the safety of tall edifices in Singapore and the feasibleness of steps that could be adopted to better the safety degrees of tall edifices. The intent of the interviews was to analyze the edifice governments attempts in turn toing the safety of tall edifices subsequently 9/11.A questionnaire was designed for the study. The first subdivision of the questionnaire want- later(a) to find the profile and demographic inside informations of the responsives. In the 2nd subdivision, respondents were asked to rate the safety degree of tall edifices in Singapore ( V1 to V4 ) on a te n-point Likert gradatory table, where 1 denotes in truth insecure , 5 denotes satisfactory and 10 denotes really safe . They were in any case asked to rate the ability of these edifices to defy accidents and onslaughts ( V5 to V6 ) on a five-point Likert graduated table, where 1 denotes strongly differ , 3 denotes neither agree nor dissent and 5 denotes strongly agree . The respondents positions on the heightened safety concern and the critical recognises related to 9/11 ( V7 to V16 ) were overly obtained utilizing the homogeneous(p) five-point Likert graduated table. The 3rd subdivision sought to find the feasibleness and pertinence of the methods bring out from the literature reappraisal. Respondents were asked to request whether they thought the proposed method should be adopted, non adopted, or were diffident. They were anyways further to notice and give grounds for their replys. The comp allowed mail study bundle comprised a screen missive, the questio nnaire and a stamped, self-addressed and envelope. selective information for the study were collected via electronic mail, draw near mail and telephone.AEs were targeted for the study because the work that they do is straight relevant to constructing safety. Eighty and clx questionnaires were sent to randomly selected AEs in the humans and hush-hush sectors, severally. Public-sector AEs were identified through the Singapore Government s published theatre directory. Private-sector AEs were obtained from profit Yellow Pages ( 2002a, B, degree Celsius ) .Besides the study, structured interviews were conducted with authorities functionaries from the Building and Construction position ( BCA ) and the upgrade Safety and Shelter business office ( FSSB ) . The intent of the interviews was to happen out their attempts in turn toing the safety of tall edifices. The BCA was selected because it is the important regulator of Singapore s building labor ( Building and Construction Author ity, 2002a, B ) . The FSSB is the local authorization in expel safety and bomb shelter ordinances ( Singapore civilised Defence Force, 2002 ) . E-mails explicating the intent of the research were sent to the governments to bespeak permission to carry on the interviews. Agreements for the interview Sessionss were so make with interviewees who were mingled in the reappraisal of edifice safety after 9/11. take after consequences and informations analysisThirty- quaternion questionnaires were have, giving an boilers suit reply rate of 14 per centum. The unre severeed sector response rate ( 28 per centum ) was higher(prenominal) than the private sector response rate ( 8 per centum ) . The correct response rate from public-sector respondents may be because the several Human Resource Departments agree to handle the questionnaires. The low response rate from the private sector respondents may be because these AEs matte that their tribal chief duty is to follow the design codifica tions, and it is up to the authorities to alter the codifications. To improver the response rate, phone calls were make to the AEs to bespeak their engagement. Unfortunately, some of the mark respondents were normally meddlesome or administrative staff were antipathetical to localise the calls through.The profile of the respondents is summarized in set back II. It can be seen that the lot of the respondents held cured(a) places in their organisations. The bulk of the respondents were applied scientists, and galore(postnominal) of them were from the public-sector lodging authorization. Furthermore, the bulk of the respondents ( 79 per centum ) had worked in the building industry for more than five old ages. This would do their feedback more ideal and dependable. Almost all the respondents ( 88 per centum ) had been complicated in the building of tall residential edifices. The public-sector respondents focuse more on residential edifices, while the private-sector respondent s were more involved in tall commercial edifices.We now reveal the profile of the interviewees. The interviewee from the BCA was a senior director who had a civil technology grade. previous to pass off ining the BCA, he had worked in the building industry for 25 old ages and was involved in the building of major just nowt and edifice undertakings. The FSSB interviewee held a sheepskin in stuffs and measures in add-on to his civil technology grade. He had worked in the FSSB for more than 15 old ages and was involved in reexamining the evict formula. The positions of these capable affair experts ( SMExperts ) were incorporated in the relevant treatment subdivisions.Datas were entered into the Statistical cock-a-hoop bucks for Social Sciences ( SPSS ) package for analysis. Average paygrades for all the variants were calculated ( delay III, column 3 ) . A one-sample t-test of the mean was carried out to look into whether the commonwealth would check with the variants surv eyed. For inconstants V1 to V4, the void conjecture ( H 0 ) that tall edifices ar regarded as insecure and the flip out speculation ( H 1 ) that tall edifices be regarded as safe are set out as H 0. I?a5. H 1. I? & gt 5. I? is the population mean, and is taken as 5 on a ten-point evaluation graduated table.For variables V5 to V16, the void hypothesis that respondents disagree with the variable and the alternate hypothesis that respondents agree with the variable are set out as H 0. I?a3. H 1. I? & gt 3. The degree of conditional relation ( I ) was set at 0.05. If the deliberate p-value is great than or equal to 0.05, H 0 is non rejected and the consequence is non significant. If the p-value is less than 0.05, H 0 is rejected and the consequence is important beyond the 5 per centum degree. The consequences are shown in tabularize III ( columns 4 and 5 ) .An independent samples t-test was carried out to find whether the public and private sector respondents shared the sam e positions on the variables surveyed or otherwise. The degree of significance ( I ) was anyways set at 0.05. The nothing and alternate hypotheses are H 0. I? public=I? private. H 1. I? publica I? private. When H 0 is non rejected, it is concluded that there is no contrast in the average evaluations by ii sectors. The rejection of H 0 agencies that both sectors of the building industry have differing positions with regard to the variable being tested. L stille s Test was apply to look into for equality of discrepancies amidst the two groups of respondents ( Gray and Kinnear, 1997 ) . It was effectuate that there was no important difference, and hence a pooled arguing of the population discrepancy was used. The consequences of the t-test of the difference between agencies are given in Table III ( columns 6-9 ) . The consequences show that there is no important difference between the positions of public and private sector respondents except for point V16. In point V16, both p ublic and private sector professionals disagreed that tall edifices should be designed to defy aeroplane onslaughts, only when private sector professionals disagreed to a great extent.In the 3rd subdivision of the questionnaire, the respondents indicated whether a suggested step should be consumeed ( agree ) , non implemented ( disagree ) or they are diffident nearly its pertinence in bettering the safety of tall edifices. The consequences are shown in Table I ( columns 4-7 ) . The four most popular methods are show issue marks with illuming at floor degrees supply a violate design codification for ace high-rise edifices supply send word safety and obstetrical delivery floors andsupply a de modify squirt system.These consequences are now discussed.How safe tall edifices are/should beThe one-sample t-test consequences ( Table III ) show that in general, the respondents are of the sentiment that tall edifices in Singapore are safe ( V1 ) . They besides have more than equal ge omorphologic design ( V2 ) , fire safety ( V3 ) and representation of flight ( V4 ) . Among the four safety appraisal of tall edifices, the average safety evaluation for structural design is highest at 7.88. Respondents snarl that this facet of the edifice is the most gravely considered in guaranting the safety of edifices. In add-on, tall edifices will be able to defy normal accidents ( V5 ) , scarcely will fall in upon an aircraft onslaught ( V6 ) .The above consequences may be biased towards the sentiments and perceptual experiences of the respondents. This is because the population surveyed is likely to react that edifices are safe because they are involved in the design procedure, and stating that a edifice is insecure brings into inquiry their design patterns. In add-on, a big per centum of public functionaries responded to this study. These public functionaries can non be seen to study no assurance in the safety of tall edifices when they have a responsibility of attenti on to normal citizens.Of the 10 steps proposed ( V7-V16 ) , six ( V7, V9, V10, V11, V13, V14 ) are importantly of import ( p & lt 0.05 ) . Respondents matte that there is a important demand to better the safety of tall edifices ( V7 ) . Consistent with this response, the respondents disagreed that tall edifices do non compel extra safety steps ( V12 ) . This shows that there is room for improvement and suffers the demand to heighten edifice safety.Respondents felt that they have the cleverness to better the safety of tall edifices ( V9 ) . The findings are promoting. It shows that AEs have the secure capableness to do tall edifices even safer. The respondents besides agreed that they have made an attempt to turn to the heightened safety concern ( V10 ) . In add-on, they will give fullest support to the building industry to turn to the safety of edifices ( V11 ) . However, this issue is non their chief concern ( V8 ) , maybe because the tall edifices are already structurally safe ( V2 ) .Respondents agreed that there is a demand for hazard appraisals to be conducted on tall edifices during the design stage ( V13 ) . These hazard appraisals will help edifice privileged decorators in placing the likely menaces faced by edifices ( Broughton, 2002 Linn, 2002 ) . Buildings are so designed to turn to the menaces to heighten their safety public presentation.Respondents besides agreed that a performance-based codification energy supply better safety exponent than the normative codification for tall edifices ( V14 ) . The SMExperts revealed that the governments have already recognized the demand for a performance-based codification because it offers more flexibleness to interior(a) decorators. For alone edifices such(prenominal) as airdromes and large-sized indoor(a) bowls, interior decorators may non be able to use the conventional normative codifications straight.The findings show that respondents are opposed to planing edifices to defy hydrocarbon fires ( V15 ) and aircraft onslaughts ( V16 ) . This may be because it will be besides expensive to construct such constructions, when the menace is improbable and unpredictable. SMExperts confirmed that edifices are designed based on possible appoint results and believable jeopardies. Aircraft onslaught is non a sufficiently believable jeopardy to be considered in the design of edifices, and therefore edifice codifications do non necessitate that such events be considered for edifices in Singapore. The deduction is that edifices may non defy such cessation impact, particularly in the front line of the resulting fires because these constructions have non been designed for such menaces.SMExperts emphatic that it is more executable to concentrate on other signifiers of menaces such as transport and handheld bombs, which are physically transported by human existences. Resources should be directed towards air violence and other security steps instead than to complain uping edifices against aircraft impact.Fire in edifices is a believable jeopardy which has been addressed in most edifice design. Harmonizing to the SMExperts, if edifices are improbable to see any menace posed by jet fuel, edifices need non be designed to defy hydrocarbon fires.How to plan safer tall edificesA ranking of the feasibleness of the proposed methods, based on the per centum of respondents who agreed with the method, is shown in Table I ( column 7 ) . For the intent of this survey, a proposed method is considered executable to do tall edifices safer when more than 50 per centum of the respondents agreed with it. Twelve methods are found to be executable and are discussed in the undermentioned subdivisions.Structural design quadruplet possible methods to better the safety of tall edifices through structural design were proposed. one(a) of these was found to be acceptable by more than 50 per centum of the respondents ( see Table I ) . The bulk of the respondents agreed with lot of sta irwells ( point 1.3 ) against rag impact. Strong stairwells are of import because flight stairwaies are the chief agencies by which edifice residents evacuate from edifices in an emergency. Existing codifications normally permit the routine of dryboards and masonry for stairwell enclosures, and these are susceptible and more flat to damage. This will do flight stairwaies to be blocked by fallen stuffs from stairwell walls. strengthen concrete walls will see higher opportunities of lasting a demolish onslaught. It is recommended that codifications be changed to indurate stairwells.The bulk of the respondents did non work with render prostration floors ( point 1.1 ) , which would be provided between, formulate every 10 floors, to transport the weight unit of the dust of the floors that prostration above it, and act as a arrest to liberal prostration ( Lane and Clark, 2001 ) . whatever respondents felt that prostration floors impose significant structural demands for illust ration, closely telld columns of larger sizes may be necessary.The bulk of the respondents did non hold with the supplying of a sacrificial facade ( particular proposition 1.2 ) . In this system, there is an outside(prenominal) wall, a perpendicular air pocket coffin nail it and another(prenominal)(prenominal) structural wall indoors. The exterior wall is designed to absorb blast impact and contain harm, and act as a first line of acknowledgment mechanism for the edifice s structural unity ( Nadel, 2002 ) . some respondents felt that this system may give architectural the look of edifices and blockade the positions of the residents. Furthermore, the facade may necessitate to be spaced far unconnected from the internal wall for effectivity, and this would take up valuable uncounted.Respondents besides did non hold that slow tonss should non be allowed on roofs ( point 1.4 ) . In the WTC towers, heavy tonss were placed on the roofs to stabilise the edifices wind-induced s way, further these could be a conducive factor to the prostration ( Building, 2001b ) . Some respondents felt that it is the norm to use rooftop unnumerable to house works and equipment such as bear motor suites and H2O fit out combat vehicles, and interior decorators may live the job of re-siting edifice work if rooftop countless is non utilised. Furthermore, for practical grounds, some M & A E systems rely on gravitational force per unit area to work.Fire technologyFour possible methods to better the safety of tall edifices through fire technology were proposed. troika of these were found to be acceptable by more than 50 per centum of the respondents ( see Table I ) .Astaneh-Asl s ( 2002 ) probe of the WTC prostration revealed that the firefighting systems were centralized at the stairway nucleus. This bunching together of the services meant that when that location was hit, the whole firefighting system may hold failed. He hence recommended that sprinkler pipes, moisture and dry risers should be decentralized, and placed at different locations of the edifice. Respondents agreed with the method ( occurrence 2.3 ) , precisely some cautioned that this would take to growth in cost.A sum of 61 per centum of the respondents agreed that supplying burden detectors ( point 2.4 ) is executable, and may increase the safety of tall edifices. Load detectors can be used to understand and acevise edifice behaviour. nimble action could be taken and exigency forces alerted one time information is provide to the monitoring system. Furthermore, burden detectors, if decently developed, are utile tools in supplying example signals to determine whether edifices are safe for first appearance during an exigency event. This would supply better protection to firemans and exigency forces, as they are able to measure the hazard of partial or entire prostration of a edifice under menace.A sum of 53 per centum of the respondents agreed that supplying a separate firemans stairway is executable ( concomitant 2.1 ) . In the WTC incident, firemans running up the stairwells move headfirst into office workers who were hotfooting down on the same steps ( get off et al. , 2001 ) . Respondents who objected to a separate firemans stairway argued that the current fire codification already has a give lift for usage by firemans. The infinite required for a firemans stairway talent be indefensible as this reduces marketable infinite and may imply lavishness building and care costs. unmatchable respondent questioned how edifice residents could be prevented from utilizing this stairway during an exigency.Respondents did non hold to planing redundancy in fire systems ( particular proposition 2.2 ) . This may be because spare standpipes for firefighting, separate fire pump suites, excess sprinkler systems, excess fire dismay systems, and double fire bid Centres will necessarily take to be addition. Some respondents weighed the pertinence of this method against cost effectivity, long-run care, cost and coif of set up and other options.Meanss of flight guild possible methods to better the safety of tall edifices through agencies of flight were proposed. Six of these were authentic by more than 50 per centum of the respondents ( see Table I ) .A sum of 63 per centum of the respondents agreed that wider stairwaies business leader be necessary for tall edifices ( concomitant 3.3 ) because these could suit more plurality to rush up emptying. Unfortunately, wider stairwaies would increase cost and cut down gross due to reduced merchantable floor infinite. There is besides argue sing cut downing the bar breadths of stairwaies because there is rarely a demand to evacuate the whole edifice at one clip, as normally but occupants on stray floors in the touched country demand to be evacuated ( Post and Angelo, 2001 ) .Supplying issue marks with illuming at floor degree ( percentage point 3.4 ) received the most support from the res pondents. Well-marked and lit marks are cardinal constructing design characteristics that facilitated the emptying of many edifice residents at the WTC Towers ( Federal Emergency circumspection Agency/American Society of Civil Engineers, 2002 ) . Such a safety characteristic would hold the extra advantage of assisting residents in following flight paths if they have to abstract on the floor. However, certain issues need to be addressed, such as the care of issue marks near floor degree, which are capable to more wear and tear and hooliganism.The construct of fire safety and deliverance floors is appealing to the respondents ( point 3.5 ) . Fireproof insane asylum countries can harbor people in the center of an emptying and service as deliverance points ( Post, 2001a ) . These countries should non incorporate furniture, and are designed to be wholly proof. Some respondents commented that proprietors may non hold to supply these countries as they can non bring forth gross but alte rnatively incur care costs.A sum of 58 per centum of the respondents agreed to the proviso of extra stairwaies in tall edifices ( head 3.6 ) . Similarly, some respondents are interested about infinite and cost. Some suggested that the figure of stairwaies be increase merely at subvert floors to provide to the big Numberss of falling residents from stop number floors. This could forestall congestion and easiness emptying, peculiarly in exigency instances affecting plentitude emptying of residents. This suggestion is a thoroughly via media between cost and safety.Fifty-six per centum of the respondents comprehend sky Bridgess to be executable in edifices ( item 3.8 ) . Besides being an alternate flight path, sky Bridgess could function as normal entree between edifices. twenty-six per centum of the respondents did non favor sky Bridgess in position of the possibility that the construction of the sky Bridgess might be affected when a edifice was under menace. Besides, sky Bridge ss could be a agency to let the spread of fire to the other edifice. A sky crossbreed that is overloaded with escapees may fall in, doing more human deaths. Some respondents, peculiarly designers, were concerned about the aesthetics of edifices.Seventy per centum of the respondents agreed that rooftop helipads could increase the safety of tall edifices ( item 3.9 ) because residents trapped in the upper floors of tall edifices can be rescued. However, there is a bound to the figure of residents that can be rescued utilizing choppers. This construct may besides be impractical because the human argument is to fall instead than go up to upper floors during exigency events. Furthermore, deliverance by choppers requires particular deliverance squads and accomplishments, which might non be readily available.The bulk of the respondents did non hold that fireproof lifts ( point 3.1 ) would heighten the safety of tall edifices. The chief concerns are the supply of electrical energy to powe r lifts, the demand to protect against power failure during fire, and agencies of flight if lifts fail. Some respondents pointed out that big crowds waiting at lift anterooms may do pandemonium during emptying. However, some respondents suggested that lifts are utile to evacuate the disableds, the aged and kids.Mr Jeremy Hodge, of Building Research Establishment Ltd, believed that another reply to get awaying to safety is the installing of flight chutes, which would non take up much room but would enable people to skid to the bottom really chop-chop ( Lane, 2001a ) . In this survey, half the respondents felt that flight chutes were executable ( item 3.2 ) . Respondents suggested that the stuff used for the flight chutes mustiness be incombustible and lasting, particularly if the system is deployed out in the unfastened. Escape chutes functioning single floors might be more efficient, and the issue points of the chutes must be decently controlled. Of the respondents that did non h old to this method, some felt that this flight means is non fit for the aged and kids. Skiding down from great highs entails high kinetic energy, and people may be injured when residents collide into one another during the sliding procedure.The bulk of the respondents besides did non hold with self-whispered emptying ( item 3.7 ) . The chief ground for the expostulation is that residents might be trapped in the edifice. Furthermore, the human inclination would be to fly an onslaught spot and people would be unwilling to wait inside a damaged edifice to be saved ( Post, 2001a ) . This expostulation by Singapore respondents is surprising because Singapore already has in topographic point an inward emptying system, in the signifier of bomb shelters being built in each high-rise flat.Behaviour of stuffs under utmost temperatureThree possible methods to better the safety of tall edifices through improved stuffs design were proposed. None of them were considered executable by the bulk of the respondents ( see Table I ) .Blast-resistant glazing may cut down casualties originating from winging folderol in the event of a blast ( Madine et al. , 2001 ) but less than 50 per centum of the respondents agreed with utilizing it to better the safety of tall edifices ( item 4.1 ) . Some respondents questioned the extent of protection, particularly in the event of an aircraft or bomb onslaught.One teach of idea is to beef up windowpane systems by cramping their corners, so that glass is more hard to interrupt ( Madine et al. , 2001 ) . However, the respondents in the present survey did non hold with this ( item 4.2 ) . One respondent warned of the possibility of over design with immense connexion inside informations, when the beef uping consequence may be limited.Madine et Al. ( 2001 ) suggested adhering the glass into window frames for greater strength as the blast burden could be transferred to the construction of the edifice. Again, respondents were non agreeable to th is ( item 4.3 ) . Some respondents considered blast-resistant glazing more effectual than adhering the glazing into window frames to control blast impact, as the strength of glass panel itself is more important. There might be troubles in building and assembly of such Windowss, in position of factors such as thermic consequence and enlargement articulations. engraves and ordinancesThree possible methods to better the safety of tall edifices through amendments of codifications and ordinances were proposed. Two of these were accepted by more than 50 per centum of the respondents ( see Table I ) .Respondents did non hold to the infliction of a height bound on edifices ( item 5.2 ) . This is consistent with old surveies ( Angelo, 2001 Forgey, 2001 Galloway, 2001 ) . In land-scarce metropoliss, guardianship compressed height bounds does non let the optimum usage of land. A height bound imposed on a edifice may forestall developers from maximizing returns on investing.The bulk of the respondents agreed that codifications may necessitate to be revised to supply for longer flight clip ( item 5.1 ) . Some respondents state that when stipulating the flight clip several factors have to be considered, such as flight waies and obstructors, occupant features ( aged, kid, handicapped, etc. ) and the location of the last individual to get away from the edifice, whether this individual is on the highest floor or at the remotest location in the edifice. It was suggested that the flight clip, if implemented, should bind in with the fire structural demands of edifices.Seventy-nine per centum of the respondents agreed that a really tall edifice should hold a separate design codification ( item 5.3 ) . The chief ground is its possible as a mark for terrorists and a long emptying clip ( Post et al. , 2001 ) . Having a separate design codification may be a good via media between safety and cost, since the codification allows a high appraisal attack to constructing design.The SME xpert from the FSSB said that his organisation has programs to revise the Fire Code every five old ages. Code demands will be refined and revise to take likely terrorist menaces into consideration. Any lacks in edifice demands that may allow terrorist Acts of the Apostless will be identified, and betterments made. The FSSB will besides implement a codification of behavior for firemans in measuring the fortunes for them to come in a edifice under menace. In the USA, security-related codifications and criterions are besides being reviewed ( Ichniowski, 2001 Lane, 2001b Maas, 2001 Pearson, 2001b ) .DecisionIn the wake of 9/11, the issue of safety in tall edifices was brought into greater central point. In measuring the safety of tall edifices originating from the 9/11 incident, this survey sought the positions of AEs and edifice governments in the building industry in Singapore.While the respondents in this survey in general perceived tall edifices in Singapore to be safe, there m ay be sample impairment because the respondents were involved in the design of edifices and many are public functionaries. nonetheless this, with rigorous authorities ordinances, all edifice designs informant functionality, lastingness and fit-for-purpose affairs. The governments interviewed attributed the good safety records of edifices to strict conformity with edifice codifications and an efficient firefighting squad. Notwithstanding this, AEs felt that it is of import to farther better edifice safety ( V7 ) . This survey besides found that edifices in Singapore can defy normal edifice accidents, but are likely to fall in upon aircraft onslaught.This paper found that AEs ( see Table III ) have the necessary expertness to better edifice safety ( V9 ) are doing an attempt to turn to heightened safety concerns ( V10 ) will give full support to enterprises to turn to heightened safety concerns ( V11 ) agree to carry on hazard appraisal during the design stage ( V13 ) andwill welc ome a performance-based design codification ( V14 ) .These findings indicate that the attack to constructing design may hold to alter after 9/11. While bing designs are equal, respondents besides felt that extra safety steps are necessary ( V12 ) . However, there is no demand to overreact to the point of guaranting that all edifices can defy hydrocarbon fires ( V15 ) and aircraft onslaughts ( V16 ) .The paper contributes to experience by bring outing that the four most effectual methods to better the safety of tall edifices are supplyingissue marks with illuming at floor degrees a separate design codification for super tall edifices fire safety and deliverance floors anddecentalisation of fire systems.Eight other steps were besides found to be executable ( see Table I ) . A height bound on edifices and limitation of burdens on roof are the most unwanted steps.Future surveies on bettering the design of tall edifices may do usage of these findings. It is recommended that farther sur veies into the strength reducing of stuffs subjected to intense fires should be carried out. This is because constructions may be able to defy the impact of aircraft onslaught, but may finally neglect after a decrease in their stuff belongingss with lifting temperature.While many of the methods proposed may be able to better the safety of edifices, increased cost is a critical concern ( Leftly and Lane, 2001 ) . Before the alterations materialize in the codifications, it is necessary to find whether the building industry is able to absorb the new steps and whether AEC professionals and clients are convinced of the demand to beef up edifices further. Safety steps proposed must be practical without doing edifice proprietors bear inessential costs. Besides seeking to do edifices stronger by supplying redundancy or more back-up beds, it is recommended that the relevant parties explore and detect new agencies to contend fire.Finally, it is of import to look at edifice safety as a whole system alternatively of supplying bit-by-bit back-up beds or increasing the marge of safety. Ultimately, each edifice may hold a alone solution depending on factors such as cost, infinite, proficient, economical and policy-making issues. A balance between practical costs and highly improbable events should be maintained.Table IPossible methods to better the safety of tall edificesTable IIProfile of respondentsTable IIIResults of study and statistical trials