Quality Assurance for Structural Engineering Firms

Transcription

1 Quality Assurance for Structural Engineering Firms Tips, Techniques & Strategies by Clifford Schwinger, P.E. The Harman Group, Structural Engineers King of Prussia, Pa. What we ll be covering* Quality Assurance Programs Quality Assurance Review procedures, tips and techniques. Structural Engineers Association of Ohio Annual Conference Presentation 9/12/13 Advantages of a QA Program The Quality Assurance Program documents procedures and standards used to facilitate design and to facilitate documentation of design. Quality Assurance is a mindset. Better design Better drawings More efficient design process Fewer mistakes Fewer RFI s / change orders Increased profit Why is a QA Program important? Fast schedules More changes during design Less experienced engineers detailing/coordinating projects Computer analysis Complex Codes RFI s / Change Orders Lost art of structural drafting Communication issues The need to be proactive 20 years ago A QA manager available to answer questions. A single QA review prior to drawings going out for bid. That process no longer works* 1

2 Today s QA process Advantages of a QA program Formal processes and procedures Ongoing QA Multiple formal QA reviews More efficient design process Less re7design More efficient QA review process Fewer mistakes on the contract documents Fewer RFI s and change orders Better training process for young engineers QA program facilitates and monitors, Selection of structural system Analysis Design and detailing Documentation of design Construction Administration The Quality Assurance Program Two useful publications Who is responsible for Quality Assurance? CASE Document 962 D, A Guideline Addressing Coordination and Completeness of Structural Construction Documents, 2003, Council of American Structural Engineers. Contractor s Guide to Change Orders, Andrew Civitello, Jr., Second Edition, 2002, Prentice Hall Everyone The attitude, He/she will find my mistakes when they review the drawings is unacceptable. The attitude, I don t make mistakes and I don t need anyone to review my drawings is dangerous. A successful QA program requires teamwork and communication. Asking questions should be encouraged. 2

3 QA Manager requirements: Components of a QA program 15 years experience (minimum) Detail oriented Good communicator Not afraid of confrontation Staff training Design standards CAD & BIM standards Project Delivery System Knowledge Base QA reviews / involvement of QA manager Staff training Some lunchtime seminar topics Formal training seminars on topics required to provide engineers the skills and knowledge needed to become more productive. Mentoring of young engineers Connection design Slabs on metal deck Joists Window washing davits AISC Lessons learned Bracing Diaphragm design Communication skills Structural drafting Load Paths Seismic design Wind tunnel studies Vibration Expansion Joints Concrete mix design Post7installed anchors Braced Frames Shop drawing review Validating computer analysis Design standards CAD & BIM standards In7house design guides, office standards and checklists for all topics related to structural design. CAD / drafting / detailing procedures Typical details go7by drawings BIM procedures & protocols Modeling standards 3

4 Project Delivery System Checklists and procedures: Project startup Schematic design Design development Contract documents Construction Administration The PDS is the roadmap that engineers follow to successfully take a project from beginning to end. The PDS eliminates re7invention of the wheel on each project. Knowledge Base Server7based database of all knowledge related to structural engineering. Similar to Wikipedia Contains knowledge not just information Contains checklists, design guides, seminar notes Involvement of QA manager Ongoing Quality Assurance Establishing and maintaining design and drafting standards Answering technical questions Staff training Review of framing plans & details before going to CAD Maintaining involvement and familiarity on all projects ( Ongoing QA ) via scheduled meetings for all projects. Performing QA reviews Maintaining familiarity with all projects as they progress through design Proactive approach to catch problems early Ongoing QA is key to enhancing efficiency & productivity The Quality Assurance Review Strategies & tactics Quality Assurance Reviews In7house reviews conducted to verify that design and documentation is in conformance with procedures, practices and standards mandated by the QA program. 4

5 Purpose of the QA review Ongoing QA makes QA reviews easier Redundancy Monitor effectiveness of QA program Catch mistakes before they get onto the drawings Catch mistakes early when they are easy to fix Typical QA review schedule Foundation permit Concrete bid Steel bid Addendum issues Issued For Construction Best to do these reviews before the drawings are issued not after. Primary strategic goal To verify that structures are properly designed Look at: Big picture load paths / framing efficiency Member sizes Critical connection details Constructability Secondary strategic goal To verify that drawings are complete, coordinated and correct View drawings through the eyes of a: Contractor Detailer Inspector Engineer performing peer review Building official Young engineer reviewing shop drawings Lawyer QA review tactics Look at the big picture Verify load paths Check framing sizes Validation of the analysis model Review constructability Check special connections Look for mistakes Look for the subtleties Look at the drawings through contractor s eyes. Review for clarity/consistency Look for omissions Look for little little things Look for big little things Coordination w/ other consultants 5

6 Look at the big picture Engineers immersed in projects can miss obvious mistakes. Load paths Connections Inefficient framing Wrong loads used Missing loads (snow drift, folding partitions, etc.) Problems with model Wrong R factor Missing or improper expansion joint layout Global stability subtleties Local stability and bracing subtleties What did the computer analysis miss? Verify load paths Any unrealistic load paths? Loads jumping in/out of shear walls / braced frames? Beware of the infinitely rigid diaphragm? Any loads on the structure not in the computer model? Example: Forces must resolve at ends of sloping columns. Example:Unrealistic distribution of lateral loads between lateral load resisting elements. Example: Questionable braced frame forces (due to infinitely rigid diaphragm in computer model). Example: Floor diaphragm not strong or stiff enough to brace the columns. 6

7 Example:floor diaphragm cut off from braced frame Example: computer software ignoring drag strut force. Check framing (gravity & lateral) Example:floor diaphragm must be manually designed. Check: Typical framing to verify the analysis model Major load carrying members Wind and seismic loads Unique framing not in computer model Always show reactions on framing plans Here s why, Makes QA review easier Load paths are easier to follow Mistakes are easier to find (computer mistakes) Forces designer to think about the connections Reduces cost because fabricator details connection for actual required strength not an arbitrary & usually overly conservative strength. Things requiring special attention Elevators Escalators Facades Davits Stairs Monumental stairs Hangers Theater rigging Trusses Transfer girders Folding partitions Special hang points Rooftop MEP loads Heavy hung piping Special loads on joists Horizontal loads from rigging Catwalks Expansion joints Unusual framing 7

8 Validation of the analysis model Review constructability Steel buildings: Will the pieces fit together? Can connections be economically designed and detailed? Concrete buildings: Is formwork economical and repetitive? Can reinforcing steel be easily installed? (Just because an FEM analysis says it works, does not mean it can be built.) Check connections Critical connections Unusual connections Connections w/ complex geometry Connections w/ large reactions Look for problems due to design changes Example: Seemingly small changes in slab edge location during design drastically affect punching shear capacity in flat plate floor slab Example: Slab opening added near column; girder shifted to avoid opening; girder now connecting to beam but beam and beam reaction not revised. Look for mistakes Wrong reactions Members too small Improper framing configurations Insufficient or missing reinforcing steel Punching shear problems Missing structural integrity reinforcing steel Missing sections and details Mistakes in sections and details Mistakes in computer model Invalid assumptions made in computer model Insufficient diaphragm strength / missing diaphragm connections 8

9 Example: Carelessness can result in objects obscuring important text. Errors like these can cause structural failures. Example: Spandrels at openings are unbraced and take lateral wind loads. Design accordingly. Facade braces and kickers can t be used to brace facade at stair openings. Look for the subtleties Column splices at inappropriate locations (mid7 height of 80 unbraced height). Framing through steps in floor slabs Floors diaphragms w/ insufficient strength/stiffness to brace columns Incorrect assumptions made in computer model Things not checked in the computer analysis The infinitely rigid diaphragm Global stability ( islands of instability ) Load path subtleties Circular framing Example: special column splices required in tall unbraced columns Example: floor diaphragms need sufficient strength & stiffness to brace columns Look at the drawings through the eyes of a contractor Envision you are building the structure and it is the first time you ve seen the drawings Is everything shown that will allow contractor to build structure without having to guess or issue RFI s? Is every foot of the building perimeter covered by a section? Is everything clearly indicated? Are there any lines on the plans that make no sense? Any missing lines? Is there any conflicting information? Can the drawings be interpreted by someone who is not an engineer? Search the drawings for potential change orders 9

10 Review for clarity & consistency Look for omissions Look for conflicts between framing plans and sections/details. Inconsistencies with framing Group similar beams Consistency = simplicity = economy Drafting inconsistencies Are sections and details cut in a uniform manner? Missing things are the hardest to find Missing, Reactions Section / details Dimensions and elevations Sizes Reinforcing steel Look for the little little things Look for the BIG little things Small drafting errors can cause structural failures. Spelling mistakes are embarrassing 7especially words like momint, sheer and engeneer. Coordination w/ architectural drawings Dimensions & slab edges Facade sections, details and support requirements Column locations Slab openings (next slide) Headroom clearances Slab elevations, slopes, depressions and steps Floor plans (verify design loads) Stairs, elevators, escalators Rooftop screen walls, MEP penthouse, parapets*. Example: Slab opening cutting off load path to edge column; opening not shown on structural drawings. 10

11 Coordination with other consultants (MEP) Example: Duct and pipe penetrations through beams MEP coordination Heavy piping & equipment loads Large ducts (headroom interference with framing) Beam web penetrations Slab embedded electrical conduit Below grade utilities Example: slab7embedded electrical conduit. Ongoing challenges Understanding software limitations Manually verifying computer analysis Architectural and MEP changes after structural design is completed. Changes during construction that slip through the cracks of the QA process. Climbing the BIM learning curve Improving communication skills Summary The six parts of a QA program, Project Deliver System Design standards Drawing & modeling standards Knowledge base Training for engineers Multiple and ongoing QA reviews during design QA reviews serve two purposes, Redundancy Monitor effectiveness of QA program. QA is a continual process (ongoing QA) Quality Assurance is everyone s responsibility Success requires teamwork and communication! Thank you! Questions? Clifford Schwinger, P.E. cschwinger@harmangroup.com Phone: