A structural appraisal is concerned with establishing the strength of an existing structure and reporting on its safety & its fitness for a given purpose.
As the structure being appraised exists, many uncertainties that existed and assumptions made during its original design can now be incorporated into the appraisal review so that a realistic assessment is done. It is difficult to cover a definitive approach in any situation, as in all circumstances the Engineer undertaking the particular appraisal is best placed to decide on the appropriate course of action.
Before starting the repairs, it is absolutely necessary that a complete assessment is done, both of the structural design as well as the existing condition of the structure.
Following reasons for structural appraisal are assumed.
- Defects in design and construction.
- Deterioration with time during its service life.
- Accidental damage.
- Structural alterations and modifications by occupants.
- Natural calamities like earthquakes, hurricanes, floods, etc.
- Due to environmental attack.
Principles of Structural Appraisal
Several buildings in our country are either inadequately designed or carelessly constructed. To add to that, many occupants of these buildings do not bother about maintenance and timely repairs.
Often, structural modifications are carried out in the guise of interior decoration, and additional loads are introduced without any structural consideration. This often acts as the last straw on the camel’s back and ultimately results in a disastrous failure or collapse.
The structural adequacy has to be examined, for the following problems, by the appraiser-
- Overall stability.
- Dynamic response.
- Geometric permanence.
- Fire resistance.
The appraiser will be usually asked the following questions by the clients (owners or occupants)-
- Is the structure adequately safe now?
- Can it be used for its intended purpose and can it continue to be used in the future also?
There is an absolute measure of adequate safety and even less for serviceability. However, the accepted level of safety provided for design and construction in accordance with current regulations and codes of practice does exist. This level of safety provides a useful datum, but engineering judgment should take precedence over compliance when assessing existing structures, with detailed codes of practice for structural design.
The processes for the design of new structures and for appraisal of existing structures are quite different even though many of the detailed calculation steps may be similar. Existing structures are subjected to various hazards which may threaten their structural adequacy. There is the risk of failure (probability) and consequence of failure. Ultimately, safety is judge subjectively and is the perception of the interaction of these two failures.
The important factor in determining the consequences of potential danger is the rate at which local failure may lead to more widespread damage or collapse. Often a small failure requiring little energy to trigger off can feed the failure mechanism enabling widespread damage to occur rapidly. Therefore, it is important to determine the consequences of a potential structural hazard and the rate at which this local failure will lead to move widespread damage or collapse.
Procedure for Structural Appraisal
The first step is the receipt of a written brief from the clients giving their clear requirements and stating the purpose for which they require the structure to be appraised.
It may also be necessary for the Engineer to assist the clients to develop this brief. This is generally done after a brief preliminary inspection on site.
Scope for Structural Appraisal
The engineer needs to do the following:
- Establish the purpose for which the client requires the report.
- Clarify to the client clearly what is being done and what he should expect from the report.
- Establish the general terms, the procedure for appraisal, and the aim. He must try to work within these terms.
- Clearly give the extent of the appraisal (e.g. Physical investigations may require chipping, opening-up, drilling, extraction of cores, etc.)
- Clarify and give an initial estimate of the cost of the appraisal.
- Advise with cost and payment terms if other agencies or testing houses are to be engaged.
- Establish the time required for appraisal and final report.
- Keep the client fully informed of all continuing financial implications and obtain approval of any special expenditure if necessary.
- Advice the client on the need to seek legal advice.
- Ensure proper legal agreement clearly setting out appraiser’s rights, obligations and charges.
- Define clearly the drawings and documents he needs from the clients and if the same are not available define the costs required to prepare or obtain these from Statutory Bodies or from other sources.
The appraising Engineer must always remember the following:
- He should decide before taking the appraisal whether the brief is morally and professionally acceptable.
- He should remain objective at all times.
- His client’s interest should be given utmost importance and he should avoid playing too safe in the appraisal or giving undue thought to personal responsibilities.
- He must be fully aware of his responsibility for public safety and property.
- He must avoid irrelevant and derogatory statements whether made in writing or orally even if this is apparently in the client’s interest.
- He must respect the reputations and feelings of others involved.
The first stage of structural appraisal requires obtaining details of design, construction, and the conditions to which the building has been subjected or is likely to be subjected. The valuable information on the design, construction, and history of the structure can often be obtained from documents prepared or the original design and construction and for subsequent additions or alterations if any. Substantial time and cost can be saved if dimensioned drawings with full structural details are available.
However, in our country, most of the time these details are not available with the clients and are also extremely difficult to obtain from the statutory authorities or the builder or their structural engineer. In most cases, the engineer will have to search for information and/or obtain information from the primary source i.e. the structure itself. However, this would need time, would be expensive, and would cause disturbance to the occupants during the physical investigations that may be necessary.
Even if the details are available, the engineer must check it against the evidence from the structure itself by inspecting, opening up, and testing.
In our country, many structures have been inadequately designed violating the prevailing codes of practices and building bye-laws. This could be due to the fact that the structural engineer has given priority to economics rather than safety and technical considerations. It could also be due to the fact that our codes of practice take a long time to revise and the building was designed, taking into considerations outdated but then prevailing codes of practices. While appraising, these considerations have to be very carefully examined.
It is also a prevalent practice amongst occupants of the building to make several changes and additions within their flats or premises owned/occupied by them. The common changes being additional partition walls, installing large water tanks, installing mezzanine floors/lofts, chasing of concrete columns, beams to encase water pipelines, electrical conduits, etc., and most importantly, removing reinforcement steel due to such encasements. Many high-rise buildings are on stilts and the occupants/owners often try to chamfer the corners of the columns or cut off the tie beams partially to create space for easy maneuvering of their cars or for creating headroom respectively. An appraiser has to look out for such acts of structural butchery during the site survey.
The construction of many structures has not been properly supervised and quality control neglected. As a result, the structure displays deterioration within a short period and even collapse causing enormous loss of life and property.
Data Collection for Structural Appraisal
Data which is to be collected from the owners of buildings or from the co-operative housing society.
- Drawings of the building approved by the Municipality/Statutory body.
- “As-Built” foundation, structural and architectural drawings along with structural design calculations.
- History of the buildings.
The following information is vital.
- Data of construction/Date of extension.
- Types of foundation.
- Repair carried out if any.
- Types of repair carried out.
(a) Structural repair – cutting/redoing/guniting/patching/any other treatment
(b) Waterproofing – terrace/canopies
(c) Miscellaneous – work in stilt area, external plastering and/or plastering in common area.
- Specific defect observed during its life.
- Interior works done by various occupants and changes executed.
- Leakage/seepage/dampness observed in the following and since when.
- External walls or walls in common areas.
- Overhead tank.
- Terrace slabs/toilet slabs.
- External soil pipes/wastewater pipes/rainwater pipes.
- Internal water, drainage, and sanitation lines
- Ponding of rainwater in building surrounding.
- Any damage caused to the building due to impacts or natural calamities.
From Various Occupants
History of the flats/premises.
- Any additions/alternation made such as
- Removal/addition/shifting of walls.
- Addition or shifting of toilets/baths/kitchen.
- Enclosing balcony.
- Changing flooring.
- Concealing electric conduits, water supply lines in masonry, or reinforced cement concrete works.
- Any other such as routing new service lines through the structure.
- Any repair carried out in the past.
- Waterproofing – toilets/chajjas.
- Miscellaneous works – toilets/chajjas.
- Changing service lines, electrical conduits (concealed/unconcealed).
- Leakage/seepage/dampness noticed inside the flat/premises and probable source and since when.
- The dampness of the ground floor wall/flooring.
- External walls.
- Internal walls.
- Terrace/roof slab/canopies.
- In walls, in plaster/masonry.
- In structural members – columns, beams, slabs, walls, chajjas.
- Concrete spalling.
- Spalling locations.
- Whether steel reinforcement is exposed and corroded.
- Lifting of floor tiles.
- Defects in doors and windows in its operation.
- Toilets piping – concealed/ or open leakages if any
- Miscellaneous information.
Other Source of Information
During appraisal it may be necessary to approach other sources for data.
The following sources may also be useful.
- The architect who had planned the building.
- The structural engineer had prepared the structural design, structural drawings, and specifications.
- The contractor/builder who was responsible for the construction initially. He will be in a position to throw more light on construction methodology. Construction defects due to delays, availability, and types of materials used in the construction, geological, and subsoil data can also be obtained.
- The agency that might have carried out some repairs or specifications or changes to the structure, may be in a position to throw some light on the extent of repairs carried out and methodology of repairs adopted.
- Municipal Engineers can throw light on the construction and other activities that had been carried out around the building after the building was constructed. Information about any addition and alteration done in the buildings and surroundings after original construction can be very valuable.
Types of Deficiencies/Disorders
The checklist is given below showing the classification of deficiencies/disorders that can come in very useful to the engineer or his client during the inspection.
The deficiencies or disorders can be broadly classified as follows:
|Sr. No.||Types of Deficiency/Disorder||Problem at Present||Problem at a later stage|
|1||Functional||The structure fails to perform its intended function e.g. seepage, leaking in water tank, walls, roof or water supply/drainage system.||Corrosion of steel, spalling of concrete, and reduction in durability and failure or collapse of the structure.|
|2||Structural||Single or more structural members not performing structurally e.g. a beam deflecting excessively||Develop cracks, moisture and another chemical ingress, corrosion of steel spalling of concrete, and reduction in durability and subsequent failure or collapse.|
|3||Minor||Shrinkage, expansion/contraction cracks||Ingress of moisture and other chemicals, corrosion of steel spalling of concrete and reduction in durability, and subsequent failure or collapse.|
|4||Chronic||Crushing of a member, disintegration of a member||Dangerous for structural stability as failure can occur within a short period.|
|5||Stabilized||The defect does not progress e.g. Domant cracks between RCC framework & masonry, settlement cracks due to foundations.||This disorder does not progress. After initial settlement/cracking further settlement stops and formation stabilizes. If the concrete element has cracked then they have to be sealed using proper sealant, otherwise, deterioration or failure can occur as stated above.|
|6||Progressive||Defect goes on increasing in magnitude with time e.g. Active cracks due to poor founding strata, deflection under increasing load, creep deflection.||This disorder is dangerous to the stability and life of the structure and therefore root cause needs to be identified to arrest the same. Otherwise, deterioration of failure can occur as stated above.|
Distresses and Their Causes
The engineer now has to identify the type of distress/damage and the cause of this defect, so that he is able to suggest further investigations and/or remedial measures accordingly. This identification can be done by visual inspection or detailed testing and analysis.
Distress in concrete structures can be due to one cause or a combination of causes. The latter is generally observed to be more prevalent. Therefore each and every cause has to be identified for a proper appraisal. Some causes generally observed are listed below:
- Underestimations of loads, deflections, shear forces, and moments.
- Overestimation of material strength and concrete strength.
- Overestimation of stiffness.
- Environmental conditions, for durability, neglected wrongly, specifying concrete grade, maximum water to cement ratio, and minimum cement content.
- Poor detailing especially at beam/column junctions.
- Faulty analyses.
- Earthquake and wind force not considered at all or inadequately considered.
- No thought given to the constructability of the structure at the time of design.
- Poor quality cement (low strength, lump formation, adulteration, inadequately stored).
- Poor quality steel (purchased from unauthorized re-rolling mills).
- Contaminated water (presence of chemicals and other impurities).
- Contaminated aggregates (presence of organic impurities, clay, and silt, and stone dust).
- Alkali aggregate reaction.
- Choice of type of cement and aggregates not suitable to the environment.
- Inadequate control and poor practice on batching, mixing, transporting, placing, compacting, finishing, and curing of concrete mainly leading to cold joints, honeycombs, air entrapment, segregation, and poor strength.
- Inadequate cover of concrete to steel reinforcement.
- Use of poor quality cover blocks.
- Poor formwork and staging.
- Poor preparation of construction joints.
- Moisture and chloride attack.
- Sulfate attack.
- Acid and other chemical attacks.
- Thermal variations, hot and cold cycles.
- Moisture movements, wet and dry cycles.
- Freeze and thaw cycles.
- Cyclones and hurricanes.
- Abrasion, wear, and tear.
- Loading and unloading cycles.
- Failure of load-bearing soil strata.
- Soil consolidation.
- Variation in moisture content.
- Slope instability.
- Soil shrinkage and swelling.
- Settlement due to cavities, vibrations, excavations close to the foundation.
- Soil erosion.
- Ground movement or liquefaction of soil.
- Reckless structural modification or alternation.
- Blasts and sabotages.
- Poor or no maintenance.
- Installation of additional load beyond the capacity of the structure.
Structural Appraising Engineer has to identify Several Defects or Damages in Structures
Due to several reasons stated above the structure gets damaged and deteriorates and needs maintenance or repair. The structural appraising engineer has to clearly identify these defects and their possible causes, suggest investigations if necessary, and recommend remedial or corrective measures. Brief details are tabulated below.
|Sr. No||Visible Defect||Possible Causes||Investigation Suggested|
|1||Rust on surface.||Iron compounds in aggregates, nails/wires left in formwork.||Chemical analysis of samples.|
|2||Rust stains on surface.||Of binding wires, corrosion of reinforcement steel.||Check cover and carbonation of concrete.|
|3||Cracking of concrete cover, exposure of reinforcement and spalling of concrete.||Corrosion of reinforcement and other steel due to moisture and chloride ingress, frost attack, and poor quality of concrete (low density, high porosity, and high water to cement ratio).||Check cover, test for chlorides and carbonation, check reinforcement adequacy.|
|4||Surface crazing.||Mix too wet and poor curing.||Check concrete mix and construction method used.|
|5||Random diagonal cracking, lateral cracking at equal spacing.||Inadequate protection against shrinkage, over-rich or over wet and non-cohesive concrete mixes.||Check reinforcement, spacing of joint, analyze maples of concrete.|
|6||Repetitive vertical or horizontal cracks.||Joint spacing too large, shrinkage, link corrosion.||Examine joint details/spacing. Check concrete sample and aggregates used.|
|7||Wet and damp spots, deteriorated applied finishes without cracking.||Honeycombs dye to poor placement or concrete mix, poor compaction, or water stopper missing.||Check concrete after recovering applied finishes, check to detail of joints, check for water stopper, test and analyze concrete.|
|8||Checks at intervals.||Restrained shrinkage, reinforcement too near the surface, corrosion of reinforcement steel, moisture movements.||Check to space of joints, check the distribution of reinforcement, concrete sample.|
|9||Water penetration through cracks.||Faulty movement joints, faulty or missing water stopper, inadequate or improperly constructed joint, inadequate reinforcement.||Check concrete at joints, check water bars, and reinforcement details.|
|10||Rust stains below mortar covering of external prestressing.||Tendon corrosion, poor grouting of tendons.||Check locations/extent of corrosion.|
|11||Map cracking.||Alkali-silica reaction, early drying out conditions, over-rich mixes, over compaction, and poor curing.||Check concrete constituents, petrographic analysis.|
|12||Surface abrasion.||Excessive wear.||Check abrasive loading. Check the quality of the concrete surface and check the history of usage.|
|13||Cracking of spalling with or without staining (generally parallel to the direction of reinforcement steel).||Corrosion of reinforcement steel or prestressing tendons, corrosion of encased steel, alkali-silica reaction, restrained by reinforcement.||Check the condition of embedded steel, check cover, carbonation, chloride content, check the presence of alkali-silica reaction.|
|14||Deflection.||Shrinkage aggregate, premature removal of formwork, overloading.||Analysis of concrete samples, design checks.|
|15||Local settlements along with diagonal cracks on footings.||Poor subgrade compaction, inadequate reinforcement, ground movement due to water/erosion/mining/shrinkage clays, peat, or other causes.||Investigate foundation design and substrata.|
|16||Vertical or slightly inclined cracks on sides and soffit on central part of RCC beams.||If less than 0.3mm: Normal If wider than 0.5mm: Overload, excessive shrinkage of the slab, premature removal of props.||Check design, compare actual load with design load, check span/depth ratios with codal requirements, check temperature gradient.|
|17||Diagonally inclined cracks in beams, generally at or close to the supports.||Overloading, inadequate beam depth, inadequately provided reinforcement to prevent shear.||Check actual shear resistance against codal allowance.|
|18||Vertical cracks in RCC beams at regular intervals.||Shrinkage around stirrups.||—|
|19||Helical cracks in RCC beam face and extending around the section perimeters.||Torsional shear stresses.||Check actual torsional resistance against codal requirements.|
|20||Excessive deflection of RCC beams.||Inadequate depth, over-loading, formwork defect, inadequate or displaced reinforcement, shrinkable aggregate, materials defective or deteriorated, bond failure between reinforcement and concrete.||Check span/depth ratio with codal requirements, compare actual and theoretical deflections, check loading history, cover meter check, and test concrete, check for defects in construction.|
|21||Prestressed concrete beams with excessive deflection, excessive hanging, loose or defective anchorage segment separation, grout disturbance and distribution not proper, segmental shear cracks.||Overloading, overstressing or poor concrete, tendon, fracture, inadequate prestress, displaced tendons, material defective or deteriorated.||Check deflection, and stresses against actual load, check conditions of all tendons, check design, check cover by the cover meter.|
|22||Bowing of prestressed columns.||Distortion during erection, concrete creep or concrete shrinkage, tendon fractures, defective material, or material deterioration.||Check loading conditions, check design & construction defects, check cover by cover meter, check tendon condition at any fracture.|
|23||Excessive deflection in slabs and/or heaving of tiles or cracking of tiles on the top surface.||Inadequate depth, over-loading, for long period, defective formwork, inadequate or displaced steel reinforcement, materials defective or deteriorated, lack of continuity.||Check span/depth ratios with code requirements, compare actual and theoretical deflections, check loading history, check cover by cover mater, and check for shrinkable aggregates.|
|24||Cracking of slab and/or finishes over supports.||Plastic and drying shrinkage cracks, slab designed as simply supported but constructed as continuous or with fixed supports, inadequate top reinforcement in continuously designed slabs, excessive support moment relaxation, inadequate top steel at supports, top steel displaced.||Check design, check construction defects & cover by the cover meter.|
|25||Spalling of corbels, nibs, fins.||Corrosion of reinforcement, inaccurate positioning of top reinforcement, absence of reinforcement, expansion of reinforcement if present combined with elastic shortening/shrinkage of the concrete frame.||Check cover by cover meter, check cover against codal requirements, check the condition of embedded steel, check actual against design loading, check the adequacy of movement joints in panel walls, estimate thermal movements.|
|Sr. No.||Visible Defect||Possible Causes||Investigation Suggested|
|1||Wall out of plumb.||Foundation movement. |
Lack of lateral restraint movement of floors.
Horizontal forces not considered in the design. Cutting of horizontal chases. Sulfate attack on the surface. Crushing of masonry on one face.
Spread of pitched roof.
|Foundation and subsoil investigation, check the presence of the large tree, drainage, etc. |
Check lateral ties.
Check roof spread.
Check construction, chemical tests.
In a long building with no internal cross-walls: Check plumb of columns.
Check lateral tying and restraint.
|2||Vertical fractures, tapering cracks, diagonal cracks, following vertical and horizontal masonry joints.||Foundation movement, slippage of ground, overloads due to roof spread, cutting of vertical chases, sulfate attack on mortar, thermal movement, and previous structural alterations.||Check foundation design sub-soil, drainage, trees in the vicinity. |
Check roof design, check construction, and identify chases.
Check joint movements. Check previous records.
|3||Parallel horizontal cracks.||Movement due to corrosion of embedded steel.||Check the condition of embedded steel, reinforcement, tiles, etc.|
|4||Parallel vertical cracks.||Overloading, thermal movement, drying shrinkage.||Check design, check joint movement and monitor them.|
|5||Horizontal/vertical constant width cracks especially between RCC work and masonry work and adjacent to corners in masonry.||Thermal expansion and contraction.||Check adequacy of joint provision, check for the mechanical bond between RCC frame and masonry.|
|6||Diagonal cracks at corners of opening.||Overloading due to inadequate length of concrete lintel or sill, oversized opening, and insufficient spacing of opening.||Check lintel/sill sizes and design, check to load.|
|7||Oscillation under intermittent load.||Inadequate stiffness, inadequate lateral resistance, oscillating machinery, weak bed joints.||Check design and construction details, check details of bed joints.|
|8||Vertical displacement of walls.||The ground settlement, overloading, moment of supporting structure.||Check soil bearing capacity, check load, check design/construction.|
|9||Damp patches on surfaces of wall.||Inefficient or no damp proof course, moisture ingress, inefficient joints in masonry.||Check construction and masonry details.|
|10||Pealing of plaster.||Poor mix, inadequate mechanical load, application of dry surface.||Check construction.|
|11||Efflorescence.||Poor quality of bricks, moisture ingress, leakage, chemical attack, and inadequate or no damp proof course.||Check construction and masonry details.|
|12||Cracks in plaster.||Poor quality mix, too much water, silty sand, poor or no curing, confined shrinkage, temperature variations, and frost action.||Check construction and specifications.|
Sampling and Testing Process for Structural Appraisal
Sampling and testing are a part of the appraisal process. However, in many cases visual survey, the study of drawings and data, and discussion with various agencies will provide enough material for proper analysis. In such cases, there may not be any need for sampling and testing.
Generally, testing is necessary for assisting the appraiser to confirm his visual observations or to give an idea of the extent of deterioration or loss of strength that may have occurred during the service life of the entire structure or its structural members.
There will no need for sampling and testing when –
- The structure is clearly in sound condition without defects and the physical dimensions found in the survey confirm the stability of the structure for future use.
- There is no requirement to evaluate the latent problems as deterioration or defect is obvious and testing will not help the appraiser in any way.
There may be need for testing when –
- The brief requires assessment of the future life of the structure or the brief requires checking the structure both before and after repairs to ascertain satisfactory completion of repairs.
- The presence of deteriorated or deleterious material is suspected and therefore it is necessary to determine the correct cause so that preventive measures for the future can be recommended.
Testing is required to –
- Determine the extent and depth of identified defects.
- To determine the quality and/or strength of materials in place.
- To identify the mechanism responsible for apparent deterioration.
- To ascertain the susceptibility of future deterioration.
The selection of number of tests and their locations will vary from case to case and would be decided by the apprising engineer based on his experience and taking into consideration the following:
- The likely variation in material properties in the different parts of the structure.
- The extent of the problem at critical locations.
- The chances of possible error or variations due to site conditions and test procedures.
- The fact that different techniques may measure concrete properties with varying accuracy. It may be necessary to select different tests on the same member together data at various depths/thickness for the sake of accuracy and interpretation.
- The chances of identical tests producing results that are not directly comparable.
Structural Appraisal Process
This process is essentially done in three stages.
A preliminary, broad assessment o apparent physical condition, robustness, and strength of the structure have to be done. If these checks give satisfactory results then no further investigations will be necessary. If the results are not satisfactory and indicate a dangerous situation then it is important that some temporary safety measures are suggested and investigation carried out further.
A complete assessment including numerical checks together with checks on stability and integrity of the whole structure as well as that of each member will have to be carried out. Working stresses will have to be calculated using reinforced service load and conventional design methods. This often gives a better idea of the margin of safety.
If the above stages do not give conclusive results, in-depth study and analysis are a must. Such more precise knowledge of loads and material strength will be necessary either by test or measurements or by other investigations.
Structural Appraisal Report
Every structural appraisal must have a report as its end. This is what the client wants and pays for. The size of the appraisal is generally irrelevant to the care and diligence required to prepare a report. It should be clearly pointed out that the report has been prepared for the client and that no third party should rely on it in any way. The engineer shall have no liability to any third party does seek to rely on it. It may be noted that even if an appraisal has been undertaken free, it will still carry liability.
The report should have the following:
- Clarity and simplicity.
- Technical accuracy and careful drafting.
- All answers to the brief.
- Continuity and logical steps and conclusions.
- Clearly defined engineer’s responsibilities giving clearly who authorized inspection, the terms of reference and the various limitations such as physical, administrative, financial, and political.
- Clearly recorded observed facts and hypothetic interpretations are clearly distinguishable from each other.
- Cover the important background information which will even allow a stranger to the building to become aware of the full situation by reading the report.
- Discuss the accuracy and limitation of the methods or tests employed and the real significance of the findings.
- Conclusions drawn in the report should be firm, reasoned engineering judgment reached after careful consideration of the information gathered during the appraisal.
- Conclusions should be without the use of vague generalities.
- Recommendations, if required by the brief, may include appropriate engineering solutions clearly giving disadvantages and advantages leaving the final choice to the client.
- Include if necessary that recommendation advice from other building experts be sought.
- Include no comments or advice beyond the field of expertise of the author.
- The client’s comments or amendments can be incorporated in the report as long as the report remains a true and fair record of the engineer’s appraisal and continues to satisfy all the criteria outlined in the appraisal.
- Highlights of any unsafe structural conditions either to the users or to the general public must be brought out in the report or brought to the notice of the clients immediately.
- Include photographs to clearly illustrate the findings of the appraisal.
- Avoid the use of excessive photographs. Typical defects only should be illustrated together with general informative photographs of the building.
- Photographs showing a general view of the structure as well as details.
- Details on their own are often meaningless and confusing.
- Include all detailed technical information produced by the appraiser, including test results. In order to avoid unwieldy documents, such information should be given in appendixes but summarized in the main report.
Structural Appraisal Report Format
It is essential that a set format for reports is followed. To give some guidelines the report can be subdivided as follows.
- Title giving brief details of the structure, its locations, names of the client, and the appraising engineer.
- Synopsis giving brief summary of the problem, the investigations carried out including significant features, the principal conclusions, and recommendations including any important reservations and/or exclusions. Should be written after the report and must not contain anything which is not mentioned in the report.
- List of Contents is essential for reports longer than four pages.
- Terms of reference (brief) should cover the entire scope of work and the agreement between the clients and the engineer. References of all letters with their dates, names, and status of signatories must be covered. Telephonic conversation and minutes of the meeting which has resulted in changes to the brief must also be recorded.
- Documents examined must be recorded staining the source from whom these were made available. Documents that would have been useful but were not obtained should also be listed together with reasons for their non-availability.
- Description of the structure should give a very clear picture of what the engineer was investigating and should cover the history of its construction, subsequent additions/alternations along with past and present use. It should be brief and pictorial perhaps referring to the drawings and photographs in the report.
- Inspections made by various experts must be recorded with their names, dates, and observations along with the names of the client’s representatives present during the inspection. Any limitation on the effectiveness of the inspection due to circumstances beyond the engineer’s control must be recorded e.g. certain occupants will not permit inspection in their flats, scaffolds not made available or found to be too expensive, and/or ladders impractical, etc.
- Additional oral information should also be summarized with the names of the informers, description of information, and dates. The engineer’s assessment of the credibility of these statements should also be recorded.
- Sampling and testing should be covered in detail giving the nature and number of samples taken, the location from where they were taken, names of the testers and observers. It is important that mechanical tests and chemical analysis are carried out by reputable independent laboratories. As there are very few reliable laboratories, selection of the laboratory should be done with extreme caution.
- Calculation checks, which are made during the appraisal, must be covered in the report. Only typical calculations need to be included in the appendix of the report. There is no need to cover all calculations in the report. Any parameters that have had to be assumed or deduced should be given in the report. Conclusions drawn for the calculations should be stated and findings summarized.
- Discussion of evidence is the item under which one discusses the importance of each of the findings described in the earlier parts of the report. Any uncertainties remaining after the investigation & any need for further checks should be stated here.
- Conclusions should be firm and reasoned judgments reached after careful assessments of the information obtained. It is advisable to discuss briefly the accuracy and limitations of the methods employed and the true significance of the findings. Every conclusion should be based on matters covered in the early sections of the report. If discussions have been well written, the reader should at this stage have arrived at the correct conclusions unaided. This section needs therefore only contain brief paragraphs in simple language giving answers to each question raised in the brief.
- Recommendations should cover a brief description of the course of action and repair methods that are available to the client as a logical follow-up to the conclusions. The recommendations should be in clear, plain language, intelligible to the lay reader. This is absolutely important, as the implementation well have to be decided by the client, mostly laypeople, hence technical jargon should be avoided.