Professional Engineers Providing Structural Engineering Services In Buildings

Transcription

1 GUIDELINE Professional Engineers Providing Structural Engineering Services In Buildings 1995 Published by Association of Professional Engineers of Ontario Revised 12/11/98

2 CONTENTS INTRODUCTION...3 PART A. PROFESSIONAL RELATIONSHIPS AND SCOPE OF WORK...3 PART B. DESIGN AND CONSTRUCTION...4 Phase 1. Preliminary Design...4 Phase 2. Final Plans and Specifications...4 Phase 3. General Review During Construction...7 PART C. OFFICE PROCEDURES...8 PART D. OTHER SERVICES RELATED TO STRUCTURAL ENGINEERING IN BUILDINGS...9 APPENDIX A. R.R.O REGULATION 941, SECTION

3 INTRODUCTION This Professional Engineers Ontario guideline covers the services offered by engineers with respect to structural engineering work in buildings, which include preliminary design, preparation of final plans and specifications, and general review during construction. Fees for these services are listed in the PEO guideline, Schedule of Suggested Fees for Engineering Services. Fees less than those recommended in the schedule of suggested fees may not be adequate to serve clients best interests. Engineers use technical knowledge and experience to provide clients with effective, functional and economical designs, and budgetary constraints on engineering fees will generally lead to increased overall construction costs. This guideline should be read in conjunction with the foreword common to all PEO guidelines. PART A. PROFESSIONAL RELATIONSHIPS AND SCOPE OF WORK Client/Owner-The person or organization who has commissioned the work and retains the prime consultant. The client/owner is usually responsible for retaining the geotechnical engineer to conduct a soils investigation. Prime Consultant-The person or organization responsible for coordinating the building design and liaison with the client and contractor. As necessary, prime consultants are also responsible for ensuring coordination between all design professionals, including architectural, structural, mechanical, electrical engineers and other specialists. Structural Engineer-The person or organization responsible for the structural integrity of the building as a whole. Structural engineers perform structural analysis and design calculations to meet building code and project requirements. They also prepare drawings indicating the location and quantities of materials, and specifications indicating the quality of materials and required performance of structural systems. (Note: In certain types of projects, the structural engineer may also be the prime consultant.) Contractor-The person, firm or corporation contracting with the client to provide labour, materials and equipment for the execution of the work. Contractors are responsible for coordinating and supervising subtrades, and maintaining quality control and construction procedures. Temporary Works-Temporary works are installations required to provide interim access, protection, support or services for works and materials during the construction of permanent works. Unless included in structural engineers scope of work, contractors rather than structural engineers are responsible for temporary works. Contractors may be required by legislation or specifications to retain professional engineering services for certain types of temporary works. For more information, refer to PEO s Guideline for Professional Engineers - Temporary Works. Scope Of Work-When engaged to perform engineering services, structural engineers should negotiate with prime consultants or clients on the parts of the work for which they will be responsible. They may provide some or all of the basic services specified in Part B, Phases 1, 2 and 3 of this guideline. Together, all of the services specified in Part B shall be considered to be full basic services. When required by clients or prime consultants, structural engineers may also provide the additional services specified in Part D of this guideline. In buildings, some structural elements are designed by fabricators, and their engineers are responsible for those parts of the work. These services include, but are not limited to, open web steel joists, preengineered steel buildings, precast concrete and deep foundations. Structural engineers are not normally responsible for such other building components as waterproofing, protection systems for floor slabs, stairs, miscellaneous metals, nonloadbearing walls and metal stud back up to veneer walls. However, when negotiated with prime consultants or clients, structural engineers may provide these services for some projects. Professional Engineers Ontario Guideline 3

4 PART B. DESIGN AND CONSTRUCTION PHASE 1. PRELIMINARY DESIGN Structural engineers should secure a definition of the prime consultant s requirements, establish parameters governing the structural design and define design procedures. They should then prepare a preliminary design concept for the structural system based on considerations of economy, performance, capital cost, accepted safety standards and compatibility with other design elements and user requirements. While incorporating client s requirements, structural engineers should: abide by the requirements of the current applicable codes, acts and regulations, to establish loadings and other parameters governing structural design; prepare preliminary structural designs for alternative concepts, describing significant components and showing materials to be used; take into account the other design professionals requirements and provide them with the information they require, and recommend to the client what other specialized services related to the structural discipline are required for completion of the project, related to the structural discipline. It is preferable that structural engineers be engaged to prepare the terms of reference for these specialized services and comment upon the reports presented, when necessary. Structural engineers should provide prime consultants with a written report on the preferred structural system and the reasons for its recommendation. The report should describe the advantages and disadvantages of the alternatives studied, and other relevant information. Structural engineers should consult with prime consultants about proposed construction materials and techniques and their alternatives, making the short- and long-term advantages and disadvantages of each choice clear, so that prime consultants can make a decision before final plans and specifications are developed. Structural engineers should also evaluate whether new materials and proprietary products have been independently tested under conditions and loadings that correspond to those anticipated during use. Certain prime consultants may prepare all or part of the foregoing preliminary design concept. In these circumstances, structural engineers are commissioned to prepare final plans and specifications based on preliminary designs provided by prime consultants, who take responsibility for the design s relative economy and suitability for construction. PHASE 2. FINAL PLANS AND SPECIFICATIONS Structural engineers should develop a final design of the structural system, based on the approved or accepted preliminary design. The final design should include plans and specifications that will ensure that the system, if built in accordance with the plans and specifications, will be in compliance with the building codes and good engineering practice current at the time of design. In preparing final plans and specifications, structural engineers should: analyze and design the structural system in conformity with applicable codes and regulations; analyze and design each element of the system or, where elements are to be provide appropriate design criteria; designed by others, prepare legible design briefs stating the applicable codes, loads, assumptions, design criteria, calculations and computer data used for the analysis and design of the system and its components; cooperate with the other design professionals during system design, responding to their requests, taking into account their requirements, and making known to them through the prime consultant functional aspects of the system that may affect the design of their systems; cooperate in the preparation by others of cost estimates and schedules from time to time, based 4 Professional Engineers Ontario Guideline

5 upon the most accurate information available as the design develops; advise the prime consultant to ensure that elements designed by others are carried out by licensed professional engineers, according to specifications and building code requirements, and if necessary, recommend to prime consultants that an independent testing agency monitor the fabrication and installation of products and test the materials used for compliance with specifications. When clients or prime consultants have not retained an engineer to prepare a geotechnical report, structural engineers should clearly indicate on the drawings the design assumptions used to prepare foundation plan(s). They should advise prime consultants that the assumed conditions must be verified by geotechnical engineers during construction, and that the designs may have to be changed. They should also advise prime consultants that additional design and construction costs and project delays can result, when site conditions that were assumed are not actually realized. Contract drawings, prepared by or under the direct supervision of structural engineers, should clearly define the complete extent and detail of the work. The drawings should include, but not necessarily be limited to, the following. a) General items: engineer s seal, signature and date of issue; purpose of each issue; applicable design and construction codes, standards and bylaws governing the work; materials to be used, including standards and grades; design loads and criteria for manufactured components; the lateral load resiting system; provisions for future extensions, if applicable; sequence of work, if this is critical to the function of the finished structure; expansion, construction and control joint locations and details; existing structural drawings, condition surveys and special reports prepared by others, when necessary; structurally derived dimensions (generally, grid line and overall building dimensions should preferably be shown, or the architectural drawings, to avoid the duplication of dimensions and possible errors), and design criteria giving the appropriate information for all vertical and horizontal loads, designating them as live or dead and specified or factored. Drawings should also include deflection limits for fabricator designed elements, snow accumulation diagrams and wind pressures. b) Foundation plans showing: type, sizes, details and locations of foundations for columns, walls, piers, special equipment and other structural load bearing components; drainage and dewatering requirements, if critical to the structural design; assumed bearing elevation of foundations; insulation details for shallow foundations, if required; design soil or rock bearing values, with reference to pertinent geotechnical reports, and the location of existing services, foundations and site information made known to structural engineers by others, which may conflict with structural footings or foundations. In addition, where underpinning and/or shoring is specified to be designed by others, structural engi- Professional Engineers Ontario Guideline 5

6 neers should indicate on the drawings the areas to be underpinned or shored, the maximum allowable deflections and settlements, and other restrictions or criteria. When structural engineers are designing underpinning, they should indicate on the drawings adequate details and construction sequences. c) Framing plans of floors, roofs walls and ancillary structures showing. sizes and locations of all members; major member openings and framing details; reference elevations of floors or roof(s); reinforcing bar sizes and quantities for concrete members, with fabrication and placing criteria; conditions at change of elevation of the structure, conditions at intersections of different structural materials, and at interaction of structural and non-structural components; direct forces, moments, shears or torsion required for the preparation of shop and detail drawings, and standards to which detailing should conform. Structural engineers should also differentiate between live and dead and specified and factored loads, to avoid possible confusion. Connections between similar materials and materials manufactured offsite are generally designed by the supplier s engineer, to the structural engineer s approval. d) Column information showing: elevations of top and bottom of columns; member sizes; reinforcing steel details for concrete columns; proposed splice locations for structural steel and concrete columns, and column axial loads and bending moments to be resisted. e) Structural details of masonry bearing and shear walls, including details of reinforcing, support of loads, lintels and grouting procedures. f) Structural details of reinforced concrete elements, openings in members, change in floor elevations, sufficiently detailed to enable others to prepare shop drawings. g) Elevations and details of custom designed trusses, including direct forces, moments, shears and torsion to be resisted by each member. h) Subgrade preparation for slabs on grade, based on the geotechnical engineer s recommendations, and slabs on earth thickness and elevation of main slab. Drawings should also make reference to other contract drawings for such additional details as recesses, depressions, pits. i) Design loadings, details of reinforcing steel, if any, and the location and details of control and expansion joints. Structural engineers should provide the technical sections of specifications for all structural design work for which they are responsible. The specifications should cover: the scope of work; standards, codes and bylaws governing the work; submittals required; 6 Professional Engineers Ontario Guideline

7 quality control requirements; materials and tolerances; workmanship and fabrication; criteria for temporary works; field review of construction, inspection and testing; provisions for the contractor to provide notification before commencing significant segments of the work, and warranties. The specifications should make it clear that the structural engineer s review of shop drawings and inspection and testing by independent agencies are both undertaken not for the contractor s benefit, but to inform the prime consultant of the quality of the contractor s performance. Contractors shall provide their own independent quality control program. During the tendering period, structural engineers should assist prime consultants in answering questions raised by the tendering contractors and, when necessary, prepare addendum (a) to the construction documents. PHASE 3. GENERAL REVIEW DURING CONSTRUCTION 3.1 General Where required by the Building Code Act, a structural engineer, either the one who designed the structure or another qualified in structures, is required to provide general review services during construction of the structure. PEO s Performance Standard for the Review of a Building During Construction must be followed during the course of phase 3. This performance standard may be found in R. R Regulation 941 (section 78), made under the Professional Engineers Act R S , Chapter P.28, and is included in Appendix A. Before commencing office or field review duties, structural engineers should provide a written report to the prime consultant on the details and extent of the rational sampling procedures they propose to follow in their review of the contractor s performance. 3.2 Office Functions In office functions, structural engineers should: a) advise contractors on the interpretation of the structural drawings and specifications, and issue supplementary details and instructions during the construction period, as required. If an engineer other than the structural design engineer carries out the general review, then that engineer should consult the structural design engineer if and when assistance is required to interpret the drawings and specifications, or when changes to the original details are being contemplated. b) review shop drawings, including confirmation that: the submittal has been reviewed by the general contractor; shop drawings and submittals are in general compliance with the contract documents and intent of the design; proprietary structural elements and preengineered components follow contract documents for specified loadings and other criteria, and shop drawings bear the seal and signature of the engineer responsible for the design of connections, components or preengineered structures, where required by specifications. Note: Shop drawing review generally does not include detailed checking of dimensions or extensive checking of calculations. c) when requested by the prime consultant, review the construction schedule and procedures proposed by contractors and comment on the methods and sequence of work, as they relate to the structural drawings and design. Professional Engineers Ontario Guideline 7

8 d) when requested by the prime consultant, advise on the validity of charges for additions or deletions and on the issue of change orders. e) when requested, examine guarantees, warranties, bonds and other documents included in the contract for conformity with the drawings and specifications, and report findings to the prime consultant. f) when part of the agreed scope of services, prepare terms of reference covering the work of independent inspection and testing companies. Structural engineers should then review these companies reports in conjunction with their own field reviews. 3.3 Field Review During Construction Field review during construction must be conducted in accordance with R.R Regulation 941. Construction safety and procedures to achieve the completed structure are the contractor s responsibility (see PEO s Guideline for Professional Engineering Services - Temporary Works). For field review during construction, structural engineers should: a) before the work begins, establish a procedure with the prime consultant whereby the contractor is responsible for informing them of the start of each significant phase of the work, so that they can properly schedule field visits. b) make sufficient periodic visits to the site to monitor the progress of the construction or installation of a representative number of each system component. During such visits, structural engineers should apply the previously defined rational sampling procedure, or such additional sampling as may thereafter become appropriate to the work. They should prepare written reports on each visit, providing copies to the contractor, prime consultant, building department and others, as agreed to at the beginning of the construction phase. c) record deficiencies observed during each site visit and bring them to the contractor s site representative s attention. Structural engineers should record such deficiencies and discussions in their site visit reports and issue these reports to the prime consultant, chief building official and others, as agreed to at the beginning of the project. d) report in writing to the prime consultant regularly on the progress of the work and observed deficiencies and problems. During subsequent meetings with the prime consultant, structural engineers should report on the condition of previous deficiencies and problems, to assess whether the condition has been or will be made good. Where the work of trades is continually substandard to industry and code standards, they should recommend resident engineering services to prime consultants. e) when part of the agreed scope of services, review and comment on the contractor s applications for progress payments and estimate completed work in place and materials on-site, to determine payment according to the terms of the contract. f) attend job meetings where structural matters are being discussed. PART C. OFFICE PROCEDURES In office procedures, structural engineers should: a) recommend to prime consultants when specialized services are necessary, including soils investigation, vibration monitoring, model studies, material testing, inspection of shop fabrication, etc. b) organize design procedures in logical sequences, to determine vertical and lateral design loads, establish the lateral stability system and procedures to check the design, verify the validity and determine the limitations of the engineering software used in analysis and design, and ensure that modelling input and results are reliable. c) maintain an up-to-date library of codes, standards and handbooks for requirements and recommendations. Sources of publications include, but are not limited to: National Building Code of Canada and the Supplement to the National Building Code, Ontario Building Code; Canadian Standards Association; 8 Professional Engineers Ontario Guideline

9 Canadian Institute of Steel Construction; Canadian Sheet Steel Building Institute; Canadian Portland Cement Association; Canadian Wood Council, and Canadian Prestressed Concrete Institute. d) ensure that all drawings and engineering calculations are prepared under their direct supervision, when their seal will be applied to the drawings. PART D. OTHER SERVICES RELATED TO STRUCTURAL ENGINEERING IN BUILDINGS 1.0 General The following services are not part of the basic services provided by structural engineers, as specified in Part B. Structural engineers should provide the following services only if they are engaged by prime consultants or clients and they have the experience and ability required to do so. 1.1 Advisory Services Advisory services include testimony, consultation and advice, appraisals, valuations, research or other services leading to specialized conclusions and recommendations. 1.2 Feasibility Studies Feasibility studies involve preliminary engineering studies and the collation and processing of information, to recommend a plan or course of action for projects. They include exploration, gathering of topographical and other site-condition information, subsoil investigation, analysis of conditions, economic studies of capital, operating costs and other financial considerations, and similar studies on which recommendations for projects will be based. 1.3 Construction Cost Estimating Construction cost estimating services include comparative cost estimates for preliminary and final designs, as required by clients or prime consultants. Structural engineers should indicate that since actual costs are dependent on conditions beyond their control, they cannot guarantee the accuracy of such estimates. Prime consultants should engage cost consultants for cost estimating when it becomes a priority. 1.4 Surveys of Existing Structures Surveys of existing structures may include elaborate surveys or measurements, and structural evaluations of existing buildings for strength and stability. These surveys may also include the gathering of information on special existing loadings, e.g., unusual machinery or construction. 1.5 Search of Records These may include searches of such records that may be held against the property as rights, restrictions and easements, and for information concerning underground services. 1.6 Revisions to Drawings and Specifications These services include extensive revisions to drawings and specifications, due to changes originated by prime consultants or clients after the commencement of final plans and specifications. Revisions to drawings and specifications may be necessary, for example, when clients or prime consultants do not obtain a geotechnical report before the design and construction phases begin. Professional Engineers Ontario Guideline 9

10 1.7 Architectural Works Architectural works include stairs and handrails, curtain walls, miscellaneous metals, building finishes and appendages, signage, poles, decorative walls, light metal framing, and waterproofing and moisture protection. 1.8 Mechanical and Electrical Works Mechanical and electrical works include equipment supports, machine foundations and light standards. 1.9 Resident Inspection Under the general review of construction, only periodic visits to the site are provided. When more detailed monitoring of field work is considered necessary, structural engineers should be retained to provide field staff on a part- or full-time basis, as required Provision of Record Drawings Provision of record drawings includes revised or completely new drawings considered necessary to show as-built conditions. Note: It is customary for structural engineers to include in the specifications a requirement for white prints marked as- built by the contractor. Record drawings should indicate who provided the information used to prepare them, and that the structural engineer does not certify the accuracy of information provided by others Preparation of Erection and Fabrication Drawings The preparation of erection and fabrication drawings includes shop drawings for structural steel, precast concrete, reinforcing steel, structural timber and other prefabricated components, and bills of materials and quantities Models and Model Analysis Models and model analysis include the preparation of physical models and their testing Translation, Conversion and Reduction These include the translation of contractual documents into a second language, the conversion of information to other mathematical units, and the preparation of drawings for reduction of scale Alternatives These involve additional work required by structural engineers, to evaluate or incorporate alternative systems proposed by the contractor. Prepared by: Wai Cheng, P.Eng. Richard De Faria, P.Eng. Robert Halsall, P.Eng. Donald Hannigan, P.Eng. Philip Meades, P.Eng. Barrie Sarjeant, P.Eng. On Behalf of the Professional Practice Committee 10 Professional Engineers Ontario Guideline

11 EXCERPT FROM R.R.O REGULATION 941 PERFORMANCE STANDARD Section 78 - The following are prescribed as a performance standard with respect to the general review of the construction, enlargement or alteration of a building by a professional engineer as provided for in the building code made under the Building Code Act. 1. The professional engineer, with respect to the matters that are governed by the building code, shall, i. make periodic visits to the site to determine, on a rational sampling basis, whether the work is in general conformity with the plans and specifications for the building, ii. record deficiencies found during site visits and provide the client, the contractor and the owner with written reports of the deficiencies and the actions that must be taken to rectify the deficiencies, iii review the reports of independent inspection and testing companies called for in the plans and specifications and which pertain directly to the work being review, iv. interpret plans and specification when requested to do so by the client, contractor or owner, and, v. review shop drawings and samples submitted by the contractor for consistency with the intent of the plans and specifications. 2. The professional engineer shall not review work in disciplines in which the professional engineer is not qualified 3. the professional engineer may delegate one or more of the functions described in paragraph 1 to another person where it is consistent with prudent engineering practice to do so and the functions are performed under the supervision of the professional engineer. 4. In paragraph 1, plans and specifications means a plan or other document which formed the basis for the issuance of a building permit and includes all changes thereto that were authorized by the chief official as defined in the Building Code Act. O.Reg. 421/86, s. 1. Professional Engineers Ontario Guideline 11

12