讲解 VQB 5642 PERFORMANCE CODES METHODOLOGY AND STRUCTURE TOPIC 6辅导 留学生Matlab语言程序

VQB 5642 PERFORMANCE CODES METHODOLOGY AND STRUCTURE

TOPIC 6: Case Study Assignment

Notes

The attached represents the form. which the final case study assignment will take.  It will form the basis of a class discussion/workshop period.

The paper purports to be a preliminary design report upon which a building surveyor has been asked to comment.   In the  assignment you are  being asked to demonstrate that you can integrate the knowledge you have learned in individual subjects by putting together an analysis of a design report.  The report is neither all good nor all bad.  It may be technically weak in some areas and fine in others; it may have errors in interpretation of the BCA, or simply fail to explain adequately the reasoning behind the arguments advanced.  You are being asked to assess it in line with the questions on the front sheet of the case study assignment.

Tips for the Real Case Study Assignment

Answering of the assignment starts with  15 minutes for reading time during which period no writing is allowed.

Start by checking that you have the number of pages indicated on the front sheet of the assignment paper.

Then take a note of the marking schedule.   The time to do the assignment, following the reading time, is three hours long and the total marks will add up to 180.  In other words, each question is valued at a minute a mark.   So as a very rough guide spend 20 minutes on a question worth 20 marks.  Try to attempt all questions, even if you run short of time.  The first few words you write on a fresh question may be worth more marks than adding a few words to a question you have already substantially answered.  In the case attached, the last question is worth a substantial mark.  Remember that and leave enough time to tackle it.

Then start to read the report.  There is no need however, to read right through it before the 15 minutes is up or before you start to answer the questions.  The assignment paper is structured so that you can read the report in sections and answer as you go.

Remember

Marks are for quality not quantity. You do not need to spend the whole of the assignment period writing. Thinking is a necessary part of answering each question well.

This is an open book assignment. Bring any material with you that you feel comfortable with. Calculators are permitted- you may download BCA freely from ABCB website.

GRADUATE CERTIFICATE IN PERFORMANCE BASED BUILDING AND FIRE CODES

FINAL CASE STUDY ASSIGNMENT (MOCK)

This paper must be surrendered after the completion of the assignment (open book). This paper is 12 pages long.  Answer all questions: a marking schedule is shown in the right hand margin

Context

The attached report represents a submission received by you from XYZ Architects for approval. Assume that the submission is made at the scheme design stage, and that detailed drawings will be submitted for approval as they become available.   Formulate your answers to the  questions as though they were comments on the report to the Architects.

Marks: total =180

Question 1

Read Sections 3-4 of the report, together with figure 1, 2 and 3. List 10 important occupant and building characteristics relevant to fire safety in this building? What else do you need to see in these Sections? 20+10

Question 2

Read Section 5 of the report.  Is the analysis/development of trial design is adequate?     Give reasons   why or why not. 20

Question 3

Read Sections 6 of the report. Comment on the design team’s interpretation of the performance clauses to be met. 10

Question 4

Read Section 7 of the report. Do you think Approaches, Methods of analysis and Acceptance criteria are clearly proposed? What additional material do you want to see? 20

Question 5

Read Sections 8 of the report.  Is the analysis of fire scenarios and other parameters adequate? 20

Question 6

Read Section 9.1. Comment on the smoke filling calculation? 20

Question 7

Read Section 9.2. Comment on the fire spread calculation? 10

Question 8

Read Section 9.1 and 9.3. Comment on the Occupant Avoidance Calculations in Section 9.3? 25

Question 9

Based on the whole report do you agree with the author’s conclusions in Section 10? What additional material would you expect to see in the final form. of a good Fire Engineering Report? 25

Submission for Comment to Building Surveyor

Sunrise Building

XYZ Architects

1. INTRODUCTION

The report describes a proposal to use the performance clauses in the BCA to introduce more cost-effective alternatives into the design  of the Sunrise Building by making use of fire engineering techniques.

2. REGULATORY FRAMEWORK

The BCA 2019 Amendment 1 will be used to establish performance requirements for the building.  In addition use will be made of the Australian Fire Engineering Guidelines (AFEG) 2021.  Where the AFEG provides insufficient detail, use is made of codes and Guidance from elsewhere, as referenced in the report.  The deemed-to-satisfy provisions of the BCA will be used here where there is no wish to depart from them.

3. BUILDING CHARACTERSTICS

A sketch of the building in plan and elevation is given in Figure 1. The Sunrise Building is a 5- storey sprinklered office building of about 3000 m2 including one basement car park level with ancillary uses such as café, meeting rooms, storage and reception areas provided for in the design.  The city site chosen is 64 m x 84 m bounded on two sides by existing buildings.  The floor-to-floor heights are 4m at ground level, and 3m at the higher levels.

An atrium passes through the building to bring natural light from roof level into the rear office spaces.   The  circulation at each level is via balconies alongside the atrium, which has the advantage of allowing flexibility of use of the tenant spaces, and access for occupants to the escape stairs without having to pass through adjoining tenancies.

There is a café located at the ground floor of the building.  For commercial reasons, the café is seen as being available for use by the public, who would enter the area by the terrace doors.

The office spaces are conditioned with cooled or heated air.  Some of the return air is allowed to trickle into the atrium causing partial conditioning of the space with air which would otherwise be wasted. There are automatically opening vents at the roof level which will control the flow of air through the atrium. The atrium is designed with a 3m high roof space constructed in glass and steel, with partial shading.   The overall system will be energy efficient and is therefore desirable on environmental grounds.

4. OCCUPANT CHARACTERISTICS OF THE BUILDING

The enclosed part of the café is 278 m2, which gives a population from the BCA of 278 people. In the atrium café seating area there would be a further 100 people and there are  1220 m2  of lettable offices which gives 120 people.  If it is assumed that the café population exits via the terrace doors, the remaining population is 220 people. The BCA requires a total doorway width of at least 1.75 m for this population with the nearest door no more than 40 m from any point.

These requirements are easily catered for by the wide main doors, and 2 × 800 mm doors to the service area at the rear.

It is assumed that the occupants are alert and mobile at the time of the fire.

5. TRIAL DESIGN AND NON-COMPLIANCES

A summary of the more important deemed-to-satisfy BCA requirements for fire safety are given in the Table for the building described above.

Departure from DtS requirements and trial designs are given below:

5.1 Compartmentation

The maximum permitted compartment floor area is 18,000 m2 under the BCA for a sprinklered building: the maximum compartment volume permitted is 108,000 m3. The building is well below these, so in principle no internal compartmentation is required if the building were to be an ordinary office building.

The BCA has special requirements for atrium buildings.  In particular, the atrium has to be separated from the floors adjoining it, if it links more than 3 floors, by fire rated construction or sprinkler-wetted glazing.  The separation may be set back from the atrium edge by up to 3.5m, in order to create a balcony for circulation. The idea of a balcony has been introduced here in order to provide general circulation routes, which allows for maximum flexibility in the layout of tenant spaces.  It is not proposed here to use fire rated construction or water-wetted glazing, but to use toughened glass panels throughout.

The tenancies will be separated from the atrium by non-fire rated construction, including large areas of full height glazing which is assumed to be tempered glass which (following the AFEG) fails at 240。C.

5.2 Egress

It is immediately apparent that compliance with the BCA requirements for travel distances to escape stairs would have introduced an awkward arrangement of three staircases.  In order to maximise lettable space and save money a design incorporating 2 stairs has been adopted here.

5.3 Smoke Hazard Management

The choice of design has serious consequences for smoke control in the atrium since the BCA requires that the smoke layer be kept 3m above the floor of the highest balcony level. The BCA determines design fires for smoke extract calculations which are steady fires of specified heat release rate and provides charts for the determination of smoke extraction rates.   With  an assumed 5 MW sprinklered fire on the floor of the atrium, the BCA would require mechanical extract  at  the  rate  of  100  m3/s.    It  is  proposed  here  that  the  natural  vents  installed  for environmental control in the atrium roof be used for smoke venting.

For smoke hazard management, it is proposed that 100m2  of smoke vents are installed in the roof of the atrium which open on detection of smoke in the atrium.  A corresponding area for makeup air opens at the ground floor reception area by means of louvres or opening vents in the exterior glazing.  The leakage paths for air to pass into the atrium under normal ventilation conditions are required to be shut off on detection of smoke anywhere in the building.  It is not proposed that pressurised stairs be included in the design.

Because of the low rise of the building, stair pressurisation would not normally be required by the BCA, but because of the atrium this becomes a requirement.  It is proposed that stairs are not pressurised here.

5.4 Detection

There will be beam detectors at the roof of the atrium which will activate the vents on detection of smoke.

5.5 Sprinklers

The building is sprinklered, except in the atrium where the ceiling is too high to permit the sprinklers to operate.

6. PERFORMANCE - BASED OBJECTIVES

6.1 Source

The basic objectives of BCA 2019 Amendment 1 are set out in the document and are interpreted in terms of functional statements which may be met either by the given deemed-to-satisfy provisions, or by alternative means.  The following functional statements have been identified as being relevant to the current problem.

6.2 Fire Resistance

A building is to be constructed to maintain structural stability during fire to

(a) allow occupants time to evacuate safely; and

(b) allow the fire brigade time to undertake search, rescue and fire-fighting operations; and

(c) avoid damage to other property

6.3 Access and Egress

A building is, as far as reasonable, to provide safe, equitable and dignified access for people to the services and facilities within.

A building is to be provided with means of evacuation which allow occupants time to evacuate safely without being overcome by the effects of an emergency.

6.4 Fire Fighting Equipment

A building is to be provided with firefighting equipment as necessary to safeguard against fire spread -

(a) to allow occupants time to evacuate safely without being overcome by the effects of fire; and

(b) so that occupants may undertake initial attack on a fire; and

(c) so  that the  fire brigade have time to undertake  search,  rescue, and  firefighting operations; and

(d) to sole-occupancy units providing sleeping accommodation; and

(e) to adjoining fire compartments; and

(f) between buildings

6.5 Smoke Hazard Management

A building is to be provided with safeguards so that -

(a) people are warned of a fire in the building so that they may safely evacuate: and

(b) people have time to safely evacuate before the environment in any effective height becomes untenable from the effects of fire.

6.6 Lift Installations

Where a lift is provided it is to facilitate safe and easy evacuation of people who due to illness, injury or their particular needs need stretcher assistance (applies to buildings with an effective height of more than 12 m).

A lift in a building must be provided with safeguards to alert occupants in an emergency when the use of the lift is inappropriate.

6.7  Emergency Lighting, Exit Signs and Warning Signs

A building is to be provided with

(a) adequate lighting upon failure of normal artificial lighting during an emergency; and

(b) adequate means -

(i) of warning people to evacuate; and

(ii) to manage the evacuation process; and

(iii) to identify exits and paths of travel to an exit.

In practical problems, not  all  of the  above would be varied  from  the  deemed-  to-satisfy provisions in any one case, and only some will be dealt with here.

7. APPROACHES, METHODS OF ANALYSIS, ACCEPTANCE CRITERIA

7.1 General Remarks

In this section, the objectives to be achieved will be set down, the criteria for demonstrating that those objectives have been met, the fire scenarios to be addressed are agreed, together with the calculation procedures to be adopted.

As per AFEG, designers need to design the means to ensure the safe evacuation of the building in the event of fire, so that the occupants can avoid untenable conditions.

7.2 Fire Resistance

It is assumed that a structural member will have met the performance-based objectives of the BCA if it can be shown that it can survive fire conditions and still carry its normal unfactored loads.  The duration for which it must survive is the escape period for structure required to support escape routes; the firefighting period for structure which is required to provide access for firefighters; burnout for structure which is required to prevent damage to neighbours.

7.3 Access and Egress

For safety of people in escaping from the building it is assumed that the following tenability criteria has been  agreed  by  all  concerned  as  satisfying  the  performance-based  objectives concerning means of escape.  The values taken from Purser for exposure for in excess of 20 minutes, with the obscuration value taken from Bryan at which people have been observed to move through smoke:

radiation:                    2.5k W/m2

CO concentration        1500 ppm

smoke obscuration      smoke less than 1.9 m above floor, and visibility <20 m

smoke temperature     smoke less than 1.9 m above floor, and temperature >100。C

The building is required to be shown to meet the performance objectives under circumstances where there is a serious fire in the cafe seating area.  The conditions on the balcony escape routes are to be analysed.  The developing conditions on the fire floor itself need not be subject to a fire safety assessment, since this situation is the same as that in a conventional office.  Only the effect of the atrium requires comment.

8.  FIRE SCENERIOS AND PARAMETERS FOR DESIGN FIRE

8.1 Design Fire

A fire will be considered on the atrium floor in the cafe seating area, which will be taken to be 5 MW controlled by sprinklers at the atrium roof.  It is assumed that the sprinklers are fast response.  In the offices, the fire will not be analysed since the office part of the building is not being dealt with by performance methods.

8.2 Smoke Production Properties

It will be assumed that the smoke is produced in the café fire arises as a result of burning of polypropylene chairs and tables.  The smoke properties given in the Guidelines suggest that the carbon monoxide conversion rate is 0.024 kg/kg and the mass optical density is 0.24 m2/g.  The heat of combustion of polypropylene is taken as 38.6MJ/kg from Tewarson. From these figures optical density and CO concentration in the smoke may be calculated.