Guidelines for Structural Engineers Jan12 c

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1 Background 1, 2 Qualifications and Expectations of Structural Engineers 1. STAGE 1 VISUAL INSPECTION 2,3 Scope of Visual Inspection 2. 4 Limitations of Visual Inspection 3,5 Coverage of Visual Inspection 3. 6 Repair Works arising from Visual Inspection 4,FORMAT OF VISUAL INSPECTION REPORT 4. 7 Main Contents of Report 4,STAGE 2 FULL STRUCTURAL INVESTIGATION 8.
8 General 8,9 Scope of Full Structural Investigation 8. ANNEX A CHECKLIST FOR PERIODIC STRUCTURAL INSPECTION OF. EXISTING BUILDINGS i, ANNEX B SUPPLEMENTARY CHECKLIST FOR CRITICAL COLUMNS. IN RESIDENTIAL BUILDING S BUILT BEFORE 1 JAN 1989 iii. 1 Background, 1 1 The periodic structural inspection of existing buildings was introduced with the. promulgation of the Building Control Act in 1989 Requirements governing. periodic structural inspection of existing buildings are stipulated in Part V of. the Building Control Act and the Building Control Inspection of Buildings. Regulations, 1 2 The periodic structural inspection applies to all existing buildings except. a detached houses semi detached houses terraced or linked houses. which are used solely as places of residence and,b temporary buildings.
1 3 Periodic structural inspections are carried out based on the following. a every 10 years for buildings where at least 90 of its floor area is used. solely for residential purposes and,b every 5 years for all other buildings. 1 4 The inspection consists of one or both of the following stages. Stage 1 visual inspection,Stage 2 full structural investigation. 2 Qualifications and Expectations of Structural Engineers. 2 1 There is a common misconception that a periodic structural inspection. involves only a visual record of the observations during a brief tour of the. building Such misconception has to be corrected The Building Control Act. requires the visual inspection to be conducted by a structural engineer who. must be a registered professional engineer in the civil or structural. engineering discipline rather than any other person It is so because of the. need for and importance of professional assessment and judgement in. structural engineering during the visual inspection Any other lesser. assessment would provide little more than what a lay person could have. observed from a casual inspection, 2 2 The structural engineer who is appointed by the building owner is therefore. expected to carry out a comprehensive visual inspection that relies largely on. his professional engineering assessment judgement and advice He shall. exercise reasonable diligence and take active and personal interest in the. planning and carrying out of the inspection of the building A situation where. he does not visit the building or totally delegates the inspection work to his. GUIDELINES FOR STRUCTURAL ENGINEERS 1, assistant or another person who is not a registered professional engineer in. the civil and structural discipline is not an acceptable practice. STAGE 1 VISUAL INSPECTION,3 Scope of Visual Inspection.
3 1 Prior to the commencement of visual inspection the structural engineer is to. obtain a set of the building s structural layout plans from the building owner. The availability of the structural layout plan will help the structural engineer to. a understand the structural system and layout of the building. b identify critical areas for inspection, c identify the allowable imposed loads in order to assess the usage and. possibility of overloading and, d verify if unauthorised addition or alteration works that affect the structure. of the building have been carried out, 3 2 In general the structural engineer is expected to carry out with reasonable. diligence a visual inspection of,a the condition of the structure of the building. to identify the types of structural defects, to identify any signs of structural distress and deformation.
to identify any signs of material deterioration,b the loading on the structure of the building. to identify any deviation from intended use misuse and abuse which. can result in overloading, c any addition or alteration works affecting the structure of the building. to identify any addition or alteration works which can result in. overloading or adverse effects on the structure, 3 3 If there are no signs of any structural deterioration or defects the visual. inspection should suffice and unless the structural engineer otherwise. advises no further action needs to be taken, 3 4 If on the other hand signs of significant structural deterioration or defects are. present the structural engineer should make a professional assessment of. the deterioration or defect and recommend appropriate actions to be taken. Such actions may involve repair works or full structural investigation to parts. or whole of the building,GUIDELINES FOR STRUCTURAL ENGINEERS 2.
4 Limitations of Visual Inspection, 4 1 There could be some difficulties in the conduct of a visual inspection as some. of the main structural elements in a building may have been covered up by. architectural finishes It is therefore important that professional judgement is. exercised by the structural engineer to determine which areas that are. covered up should be exposed for inspection Reference to structural layout. plans to determine the presence of critical structural elements would be. crucial under such circumstances, 4 2 Notwithstanding these difficulties an inspection by an experienced structural. engineer who exercises reasonable diligence would not be entirely fruitless or. 5 Coverage of Visual Inspection, 5 1 Structural engineers and building owners often question the expected. coverage of a visual inspection Owing to difficulties of access and other. practical problems it is sometimes not possible to inspect 100 of all areas in. a building within a reasonable period of time, 5 2 The danger of prescribing any percentage lower than 100 is the possibility. of doing the minimum with the possible consequence of missing something. important It is therefore generally expected that the structural engineer carry. out the visual inspection of all units or areas of a building This is especially. so for buildings where the imposed loading is high usage varied or likely to be. subjected to abuse or overloading for example factories industrial buildings. warehouses shop houses public assembly areas etc, 5 3 For other buildings where the imposed loading is light usage is fairly uniform.
and unlikely to be subjected to overloading such as residential apartments. hotel rooms general office areas or if a reduced percentage of coverage is. inevitable the structural engineer must have the inspection sampling well. distributed throughout the building and no significant defect or deterioration is. found during his inspection of the sample If the structural engineer foresees. the possibility of abuse or overloading and detects signs of significant. structural defects and possible deterioration he should consider 100. inspection of the structure, 5 4 All parts of a building with special and critical structural elements or with no. redundancy e g transfer girders slender columns cantilever structures long. span structures cable structures connections and support conditions etc. must be inspected fully,GUIDELINES FOR STRUCTURAL ENGINEERS 3. 6 Repair Works arising from Visual Inspection, 6 1 Major repairs and strengthening work where necessary shall be treated as. building works As such procedures relevant to application for approval of. plans permit to carry out building works and supervision of building works. shall apply, 6 2 Minor repairs can be treated as routine maintenance and will not require plan. submissions or permit applications,FORMAT OF VISUAL INSPECTION REPORT.
7 Main Contents of Report, 7 1 A report produced by the structural engineer is expected to be professional. clear and conclusive A stereotype report written in a manner which can be. used for any building with minor changes to its title block is defeating the. purpose of the Act On the other hand a thick book consisting of mainly. photographs with no engineering input may also not serve the purpose The. report should therefore reflect the fact that the structural engineer had carried. out the inspection in a professional manner with reasonable diligence. expected of him as a professional engineer A well prepared and professional. report is demonstrated by the engineering views assessment judgement. conclusion and follow up recommendations put forth based on the. observations Such a report is also useful for the owner as a maintenance. record for any follow up, 7 2 The following is a guide on the manner in which the Visual Inspection Report. should be prepared In addition a checklist in Annex A is to be included in. and as part of the inspection report,a General Information of the Building. Name and address of the building,Number of storeys in each block of building. Description of main usage of the building,Maintenance history of the building if known.
b Structural System of the Building, Description of the structural forms systems and materials used in. different parts of the building e g reinforced concrete prestressed. concrete steel etc, Description of the soil condition and foundation system if known. GUIDELINES FOR STRUCTURAL ENGINEERS 4, Identification critical structures and structures without redundancies. eg transfer girders slender columns cantilever structures long span. structures cable structures etc,c Diary and Scope of the Visual Inspection. Dates of inspection for different parts of the buildings. Description of any areas not covered by the visual inspection the. reasons and an assessment of whether such areas are critical to. overall structural integrity of the building,d Survey of Loading on the Building Structure.
Records of and comments on the observations on the loading. conditions indicating the usage at different parts of the building and. identifying any misuse abuse or deviation from intended use Special. attention to be paid to industrial buildings eg factories and. warehouses, State whether existing usage and loading condition is compatible. with the intended purpose of the structure, State whether any misuse abuse or deviation from intended use. has given rise to excessive loading which can adversely affect the. building structure, Recommendations on any remedial actions to be taken by the owners. e g restricting the usage relocating heavy machineries further. investigation on the adequacy of the structure, Where there is deviation from its intended use resulting in overloading. or supporting higher design imposed load as recommended in. BS6399 the need for further design check on structural adequacy and. display of allowable imposed loading signage shall be recommended. in the inspection report, e Survey of Addition or Alteration Works to Building Structure.
Records of and comments on the findings of any addition and. alteration works to the building structure Such information can be. obtained by visual inspection engineering judgement interviewing the. management corporation owners and users and checking the. drawings if available to the engineer, State whether any addition and alteration works have given rise to. excessive loading or other adverse effects on the building structure. Recommendations on any remedial actions to be taken by the owners. e g the need for the removal of the addition and alteration works. f Survey of Signs of Structural Defects Damages Distress. Deformation or Deterioration, Records of observations of any signs of structural defects damages. distress deformation or deterioration e g cracks excessive deflection. GUIDELINES FOR STRUCTURAL ENGINEERS 5, connection failure instability floor settlement foundation settlement. tilt spalling concrete corrosion of steel termite infestation dry wet. rot timber etc This could entail judicious removal of plaster or. architectural finishes to establish the underlying structural condition. The seriousness of any structural defects should be assessed. Comments on the extent possible causes and assessment of the. seriousness of these identified problems,Assess whether the identified problems are. Defects of no structural significance, Defects requiring remedial action and or monitoring.
Suspected defects of structural significance requiring full. structural investigation and immediate action, Recommendations on remedial actions and or monitoring necessary. to ensure the structural stability and integrity of the building. Where there are signs of termite attack on timber structures the. engineer shall recommend the owner to carry out inspection and. treatment by an anti termite specialist and obtain the certificate of. termite treatment accordingly, If there are signs of significant structural problems the engineer shall. make recommendations for a full structural investigation to be carried. out without further delay,g Survey of exposure to aggressive environment. Presence of column s immersed in water eg ground floor water tank. sea water lakes etc, Presence of aggressive chemical which may accelerate the. deterioration of structural elements particularly in industrial buildings. h Survey of retaining walls and slope protection structures eg soil. nails ground anchors shorcrete slope, Evidence of wall movement inadequate surface drainage unintended.
GUIDELINES FOR STRUCTURAL ENGINEERS 3 4 Limitations of Visual Inspection 4 1 There could be some difficulties in the conduct of a visual inspection as some of the main structural elements in a building may have been covered up by architectural finishes It is therefore important that professional judgement is exercised by the structural engineer to determine which areas that are covered up

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