South African Institution of Civil Engineering Institution of Structural Engineers

Standard for structural engineering services

Contents 1

Scope ............................................................................................................................................. 1

2

Definitions ....................................................................................................................................... 1

3

Requirements.................................................................................................................................. 2 3.1

General .................................................................................................................................... 2

3.2

Design of structures ................................................................................................................. 3

3.2.1

General ........................................................................................................................3

3.2.2

Design information ........................................................................................................5

3.2.3

Production information ...................................................................................................6

3.2.4

Manufacture, fabrication and construction information ......................................................6

3.2.5

Construction, repair or conducting of remedial works .......................................................6

3.2.6

Record information ........................................................................................................6

3.3

Checking of another structural engineer’s design ..................................................................... 7

3.4

Condition assessments ............................................................................................................ 7

3.5

Use of structural engineering software ..................................................................................... 8

3.6

Certification .............................................................................................................................. 8

Form 1: Structural System Certificate for structural works subject to the National Building Regulations .... 9 Form 2: Certification of Alternative Solutions (Regulation Z4(1)(b)(ii) of National Building Regulations) .. 10 Form 3: Structural works not subject to the National Building Regulations .............................................. 11

Standard for structural engineering services 1

Scope

This standard establishes requirements for structural engineers who perform services relating to the determination or confirmation of the structural safety and structural serviceability performance of structures during their working life. This standard covers rational designs, rational assessments, technical inspections, condition assessments or independent checking of designs (or any combination thereof) of structures other than a barrier constructed to retain water, in order to raise its level or reduce or prevent flooding. . NOTE: Structures include buildings, walls, bridges, water retaining structures including: swimming pools, masts, towers, silos, frameworks, and other similar structures in their construction or alteration, to ensure structural safety and structural serviceability performance during their working life.

2

Definitions

For the purposes of this standard the following terms and definitions apply. actions: an assembly of concentrated or distributed mechanical forces acting on a structure, or the cause of deformations imposed on the structure or constrained in it client: the person who makes use of the services of a structural engineer condition assessment: the evaluation of the present condition of a system or a part thereof in relation to its behavior in use to fulfill current and future required functions design life: period of time for which the structure as a whole or a component thereof performs above the specified level of structural safety and serviceability performance design working life: design life assumed for the whole structure international standard: standard that is adopted by an international standardising / standards organisation load: value of force corresponding to an action manufacture, fabrication and construction information: information produced by or on behalf of the contractor or constructor, based on the production information which enables manufacture, fabrication or construction to take place maintenance: combination of all technical and associated administrative actions during an item's service life with the aim of retaining it in a state in which it can perform its required functions maintenance schedule: series of actions and time intervals between these actions to maintain the levels of structural safety and serviceability performance of the whole structure over its design working life national standard: standard that is adopted by a national standards body production information: the detailing, performance definition, specification, sizing and positioning of all systems and components enabling either construction (where the contractor is able to build directly from the information prepared), or the production of manufacturing and installation information for construction

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rational assessment: an assessment of the adequacy of the performance of a design for a proposed, or the adequacy of an existing, structural system or part thereof including, as necessary, a process of reasoning, calculation and consideration of accepted analytical principles, based on a combination of deductions from available information, research and data, appropriate testing and service experience rational design: any design involving a process of reasoning and calculation based on the use of an international or national standard or other suitable document structural durability: capability of a structure or any component to satisfy, with planned maintenance, the structural design performance requirements over a specified period of time under the influence of the environmental actions, or a result of a self-ageing process structural engineer: a professional engineer or a professional engineering technologist registered in terms of the Engineering Profession Act of 2000 (Act No. 46 of 2000) and who is capable of: a)

communicating the environment within which structural engineering is practiced;

b)

producing viable structural solutions, within the scope of a design brief, taking account of structural stability, durability, aesthetics and cost;

c)

determining and documenting the form and size of principal structural elements for a proposed structure;

d)

specifying and co-ordinating the use of primary structural materials; and

e)

communicating construction techniques and sequencing for structural engineering

structural safety performance: behaviour of structures under possible actions related to human lives structural serviceability performance: behaviour of a structure for normal use under all expected actions that might affect the occupants and the functioning of the structure structural system: a system of constructional elements and components of a structure which is provided to resist the loads acting upon it and to transfer such loads to the ground upon which such structure is founded structure: organised combination of connected parts designed to provide some measure of rigidity, or a construction works having such an arrangement suitable: capable of fulfilling or having fulfilled the intended function or fit for its intended purpose.

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Requirements

3.1

General

3.1.1 Structural engineers shall, with an appropriate degree of reliability, determine in accordance with the provisions of this standard that the whole structure or any of its parts for which they are responsible: a)

maintains strength and stability under all actions likely to occur during the structure’s design working life;

b)

performs within established parameters under all expected actions for normal use in terms of: 1)

local damage, including cracking;

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c)

2)

deformation; and

3)

vibration; and

fulfils its intended safety and serviceability performance in the environment in which it is located over its design working life when subject to its intended use taking into account the: 1)

external and internal environmental agents (including those associated with microclimates that can arise with structures);

2)

maintenance schedule and specified component design life; and

3)

changes in form or properties.

3.1.2 Structural engineers shall in providing a professional service: a)

take reasonable care to ensure the quality and safety of all structural engineering work entrusted to them and adopt a balanced, disciplined and comprehensive approach to problem solving; and

b)

observe all applicable legislation and statutes;

c)

take all reasonable steps to: 1) 2)

understand and define the brief with the client; and ensure that the client understands the scope and limitations of the service to be provided;

d)

accept personal responsibility for their work and work performed under their supervision or direction;

e)

take reasonable steps to ensure that anyone working under their authority is both competent to carry out the assigned tasks and likewise accepts personal responsibility for their work;

f)

affix their name and any relevant registration number to all production information and record information of the structure or part thereof for which they have assumed responsibility and sign such information; and

g)

if called upon by an owner of a structure within a period of 10 years after completion of the structure or part thereof, produce the design information and record information.

3.2

Design of structures

3.2.1

General

Structural engineers when designing structures shall: a)

establish the design working life of structure as a whole and parts thereof and the associated maintenance strategy in consultation with the client or owner taking into account any legislative requirements in this regard;

b)

review all structural design concepts to determine that the structural concepts are complete, consistent and in general compliance with any relevant and appropriate or applicable national or international standards;

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c)

consider the risk of the structure being subjected to abnormal loads during its design working life and where there is a significant risk of such loads occurring, take the effects of the such loads into account in the design;

d)

not include anything in the design of the structure necessitating the use of dangerous procedures or materials hazardous to the health and safety of persons, which could be avoided by modifying the design or by substituting materials;

e)

ensure that the assumptions made and the level of reliability of rational designs or rational assessments are such that a peer review of the structural system or part thereof would arrive at a similar conclusion;

f)

ensure that the basic assumptions made in the software used in the analysis and design of structures or parts thereof (such as adequate lateral restraints) are actually fulfilled in reality;

g)

check their work, either using another method or by engaging another structural engineer to do so; and

h)

take into account the hazards relating to any subsequent maintenance of the relevant structure and make provision in the design where possible for that work to be performed safely.

NOTE 1: ISO 10845-3:2009, Houses – Description of performance: Part 3: Structural durability, indicates how three different maintenance strategies can provide acceptable performance over the design working life of a structure as illustrated below: Performance level

strategy 1 (no maintenance) strategy 2 (with repair) strategy 3 (with maintenance)

Target performance Time Design working life

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NOTE 2: ISO 15686-1:2000, Buildings and constructed assets — Service life planning — Part 1: General principles, suggests the following minimum design lives of buildings in years based on their accessibility for maintenance: Design working life of building

Inaccessible or structural components

Components where replacement is expensive or difficult (including below ground drainage)

Major replacement components

Building services

Unlimited

Unlimited

100

40

25

150

150

100

40

25

100

100

100

40

25

60

60

60

40

25

25

25

25

25

25

15

15

15

15

15

10

10

10

10

10

Easy to replace components may have design lives of 3 to 6 years An unlimited design working life may rarely be used as it significantly reduces design options NOTE 3: The consequences of failure also need to be considered when developing a brief for design working life. The consequences of failure can be categorised as indicated below (see ISO 15686-1:2000): Category

3.2.2

Consequence

Example

1

Danger to life

Sudden collapse of structure

2

Risk of injury

Loose stair tread

3

Danger to health

Serious damp penetration

4

Costly repair

Extensive scaffolding required

5

Costly because repeated

Window hardware replacement

6

Interruption of building use

Handling failure

7

Security compromised

Broken door latch

8

No exceptional problems

Replacement of light fixtures

Design information

3.2.2.1 Structural engineers shall ensure that design information is prepared to support all rational designs and, where relevant, rational assessments. Copies of calculations and inputs and relevant outputs of any computer analysis shall be filed as well as description of the software used, the design assumptions that are made, the loads that were applied, the design criteria and the relevant geotechnical information upon which the design is based. 3.2.2.2 Structural engineers shall file the following together with associated design information: a)

a foundation loading schedule which states the magnitude and direction of all foundation loads for each specific load case and indicates the load factors that have been applied; and

b)

test results, certificates of material strengths and other relevant data.

NOTE: The Joint Structural Division’s Code of Guide to Good Practice for Structural Engineering provides guidance of the preparation of design calculations.

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3.2.3 Production information 3.2.3.1 Structural engineers shall ensure that adequate production information is prepared to enable the structure to be constructed in a manner that design intent is met. Such information shall unambiguously indicate the locations, sizes and connections of the structural elements in sufficient detail to enable, as relevant, their fabrication, construction or assembly in a reasonable sequence by a competent constructor familiar with the techniques of construction for the specified structural materials. It shall also indicate the quality of the components and where necessary all member forces which are required for the design of end connections. 3.2.3.2 Structural engineers shall ensure that constructors are provided with suitable structural specifications for all structural materials. Such specification shall include requirements for materials, workmanship, fabrication, quality control, tolerances, inspection and testing. 3.3.3.3 Structural engineers shall where necessary, ensure that the constructor is provided with relevant information for temporary works, construction activities and sequencing and geotechnical information to ensure its safe construction. 3.3.3.4 Structural engineers shall ensure that any revisions, updates or new versions of production information issued to constructors for fabrication or construction purposes are identified by a unique number or other form of designation.

3.2.4

Manufacture, fabrication and construction information

3.2.4.1 Structural engineers shall review any construction or erection method statements relating to the structural system provided by the constructor and promptly communicate in writing to the constructor one of the following: a)

acceptance of the statement;

b)

qualified acceptance of the statement citing the actions that need to be taken to achieve acceptance of the statement; or

c)

rejection of the statement citing the reasons for such rejection so that a revised statement can be submitted.

3.2.4.2 Structural engineers, shall in respect of designs which incorporate structural steelwork or structural timber, ensure that any connection detail and drawings prepared by a fabricator are reviewed to ensure that the design has been correctly interpreted and that design intent is met.

3.2.5

Construction, repair or conducting of remedial works

The structural engineer shall in relation to the construction, repair or conducting of remedial works of the structural system, or part thereof, conduct inspections at such intervals as may be necessary in accordance with accepted practice to satisfy himself or herself that the design is being correctly interpreted and the work is being executed generally in accordance with the designs, appropriate construction techniques and good practice, excluding the detailed supervision and day-to-day inspection.

3.2.6

Record information

3.2.6.1 The structural engineer shall ensure that the record information of the structures for which they are responsible contains information on the following as relevant: a)

the design life and maintenance schedule;

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b)

the design standards that were applied;

c)

the loads which the structure was designed to withstand;

d)

the key geotechnical parameters used in the design;

e)

the basic engineering properties of the construction materials that were used; and

f)

the construction standards that were used.

3.2.6.2 The record information shall include any certificates issues in terms of 3.6.

3.3 Checking of another structural engineer’s design 3.3.1 A structural engineer who checks the work of another structural engineer should subject to the consent of the client inform such engineer of their appointment and, if possible, all those responsible for the original design so that they are able to freely discuss and resolve all pertinent matters. 3.3.2 If the checking engineer finds a problem in a design which he or she is unable to resolve, the reason why it is a problem shall be clearly stated and the client advised accordingly. 3.3.3 The checking engineer should obtain another opinion if the original design is considered to be seriously at fault.

3.4

Condition assessments

3.4.1 Condition assessments may comprise one or more of the following activities, as relevant: a)

technical inspection to evaluate the state of, or to assess the maintenance needs of the structure as a whole or a part thereof including as necessary: 1) 2) 3)

4) 5) 6) 7)

visual inspection;. the reviewing of asset management plans to identify relevant information; the gathering of information from maintenance records and communicating with maintenance personnel and users to understand the complexity of the structure to be assessed and any maintenance issues; the capturing of visual images on electronic or other media; physical measurements of components; non-destructive testing; and collection or confirmation of asset data;

b)

determining actions to mitigate any immediate risk until remedial works (or other actions) can be taken to address problems;

c)

the drafting of specification for repairs and remedial works;

d)

the assessment of the stability of the structure as a whole or a part thereof; or

e)

re-certification of the structural safety performance or serviceability performance of the structures assessed, particularly where the usage has changed or may change and the structure requires a fresh analysis.

3.4.2 The structural engineer undertaking a condition assessment shall promptly notify the client and owner of the structure of any structural condition that he or she may encounter, which could compromise the safety of users of the structure. 7

3.4.3 The structural engineer shall draft a report on the findings of his or her assessment in such a manner that its content is understandable to non-structural engineers. Such a report shall, as necessary, include any recommended actions and associated time frames for executing and completing such actions. It shall also document the evidence and rationale for arriving at the findings in such a manner that a review by another structural engineer can result in similar findings and recommendations. NOTE: The Government Immoveable Asset Management Act of 2007 (Act No. 19 of 2007) requires that an asset management plan developed by the custodian includes a condition assessment of immoveable assets.

3.5 Use of structural engineering software 3.5.1 Structural engineers should only use structural engineering software in the analysis and design of structures or parts thereof that have been independently validated or have been obtained from a software supplier that has in place a quality assurance program and has evidence of software validation that substantiates the veracity of the outputs. 3.5.2 Structural engineers in making use of structural engineering software in the analysis and design of structures shall ensure that: a)

the software is used within the limitations stated by the software developer and the modelling techniques upon which the software is based;

b)

the applied actions are correctly determined and modelled;

c)

the dimensions of members and layouts are consistent with the construction drawings;

d)

parameter settings and selections including member sizes, member properties, connections between members, supports and restraints, appropriately and reliably model the behaviour and expected performance of the structure, the member sizes, properties and connections between members; and

e)

account is taken of any construction actions, construction techniques or sequences in construction in the modelling of the structure.

3.5.3 Structural engineers should conduct an independent check of the output of software programs to determine that the structure, as modelled is in equilibrium.

3.6

Certification

3.6.1 A structural engineer, when required to do so, certify compliance with legislative requirements when called upon to do so. NOTE: Structural engineers are required by legislation to: • certify the structural system of a building or home in terms of the National Building Regulations and Building Standards Act 103 of 1977 or the Housing Consumers Protection Measures Act 95 of 1998, respectively; • report in terms of the Sectional Titles Act 95 of 1986 on the general physical condition of building with specific reference to any defects in the buildings and the services and facilities relating thereto; and • inspect a completed structure prior to its commissioning and issue a completion certificate to the contractor and conduct an annual inspection of a completed structure in accordance with the provisions of the Construction Regulations issued in terms of the Occupational Health and Safety Regulations of 1993

3.6.2 A structural engineer shall provide a certificate of completion whenever a new structure is constructed or altered using Form 1, Form 2 or Form 3, as relevant, and include such information in the record information.

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Form 1: Structural System Certificate for structural works subject to the National Building Regulations (Provide if a rational design or rational assessment of the structure is required in terms of Regulations A(1)(3), A23(4) or the structural aspects of Parts J, H, K, L or M of the National Building Regulations is satisfied by means of a rational design or rational assessment i.e. not solely in terms of the rules contained in Parts J, H, K, L or M of SANS 10400)

Project title Project number Buildings and associated site works covered by certificate (describe) Occupancy / Building classification(s)

(see Regulation A20)

I hereby certify as required by Section 14(2)(a) of the National Building Regulations and Building Standards Act, 1977 (Act No. 103 of 1977) that the structural system for which I am responsible has, to the best of my knowledge, been designed and constructed / erected / installed satisfies the requirements of the National Building Regulations and is in accordance with the production information that was issued to the contractor to enable construction or the production of manufacturing and installation information for construction. I furthermore confirm the following: 1

Key geotechnical parameters used in the design

(State)

2

Design and construction of structural elements

(Delete elements which do not apply, provide separate tabulations for each element)

Roof / Walls / Floors / Staircases / Foundations / Facades Design standard applied Loads (outline) Basic engineering properties of structural materials Construction standards applied Tests (state type, frequency, range of results and comment on implications of non-compliances) Critical assumptions, if any

3

Design carried out by other competent persons in terms of Regulation A19(8)

I confirm that the design of the following elements of the structural system were carried out under my direction by the following other competent persons in terms of Regulation A19(8): (Complete if parts of the system were designed by others) Element

.............................

Name

Date

Professional registration no

........

Signature of Approved Competent Person responsible for the structural system in its entirety (Regulation A19(7) and A19(8)

Name . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Professional registration number: . . . . . . . . . . . . . . . . . . . . . . . . . . . . Registration council: ECSA (Insert number)

9

Form 2: Certification of Alternative Solutions (Regulation Z4(1)(b)(ii) of National Building Regulations) (Provide if Regulation AZ4 is satisfied by reliably demonstrating, or predicting with certainty, to the satisfaction of the appropriate local authority, that an adopted building solution has an equivalent or superior performance to a solution that complies with the requirements of the relevant part of SANS 10400.)

Project title Project number Buildings covered by certificate (describe) Aspect of building covered by alternative solution Occupancy / Building classification(s)

(see Regulation A20)

I hereby certify that the performance of the solution for (describe) has an equivalent or superior performance to a solution that complies with the requirements of SANS 10400(insert part of SANS 10400)

My reasons for such certification is that (outline motivation for statement)

.............................

Date

........

Signature of Competent Person responsible for preparing a Submission to the Local Authority in terms of Regulation AZ4

Name . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Professional registration number: . . . . . . . . . . . . . . . . . . . . . . . . . . . . Registration council: . . . . . . . . . . . . . . . . . . (Insert number)

10

Form 3: Structural works not subject to the National Building Regulations (delete that which does not apply and complete where such works are not covered by National Building Regulations)

Project title Project number Works covered by certificate (describe)

I hereby certify that the works for which I am responsible has, to the best of my knowledge been designed and constructed / erected / installed in accordance with all statutory requirements and is generally in accordance with the production information that was issued to the contractor to enable construction or the production of manufacturing and installation information for construction.

I furthermore confirm that the design and construction of such work were in accordance with the following: Design standard applied Critical design parameters Basic engineering properties of materials / type of materials Construction standards applied Tests (state type, frequency, range of results and comment on implications of non-compliances) Critical assumptions, if any

Signature of professional responsible for the design of the structure

Name . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Professional registration number: . . . . . . . . . . . . . . . . . . . . . . . . . . . . Registration council: ECSA (Insert number)

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