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BIM, Autodesk Revit, Construction

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  • Building Information Modeling

    BIM for Contractors

    Jinyue Zhang @ University of Toronto 29/07/2013 BIM for Contractors 1

    Agenda Types of construction firms

    Information related to contractors from BIM

    Processes to develop a building model for contractors

    Design error detection and clash detection

    Quantity take-off and cost estimating

    Construction analysis and planning

    BIM and other management applications

    Offsite fabrication

    Use of BIM onsite

    Contract and organization changes

    29/07/2013 BIM for Contractors 2

    Types of construction firms A fragmented market

    Average firm size is 9 employees. 91.6% construction firms hire less than 19 employees. 61.6% construction employees work in small firms (less then 19

    people).

    The majority of construction firms fall in the specialty trade category (mainly small subcontractors)

    29/07/2013 BIM for Contractors 3

    Types of construction firms General contractors

    Self-perform + subcontract Construction management +

    subcontract everything

    Home builders Act as developers

    (client+contractor) Buy a land, apply for zoning

    changes, plan and construct infrastructures, design and build the home, then sell it

    Subcontractors Specialize in one area of type of work Selected by GC based on competitive bids or long-established

    collaboration

    Fabricators Produce a range of standard products and custom items, mainly offsite

    Design builders Assume responsibility for both design and construction Serve as the single point of responsibility for the entire project

  • 29/07/2013 BIM for Contractors 4

    The changing business practices The old days

    Drawings and specifications (hardcopy or softcopy) as the starting point

    Even architects used 2D or 3D CAD systems Quantity take-off in a manual approach

    Time-consuming, tedious, error-prone As a result, not much technical analysis until the very late phase

    of design Cost estimate, schedule, constructability

    The methodology is beginning to change Recognized value of BIM Early involvement of contractors, even fabricators Building models from architects to contractors

    At least, for adding detailed information about cost and schedule For construction planning, coordination, fabrication, procurement,

    etc.

    29/07/2013 BIM for Contractors 5

    Agenda Types of construction firms

    Information related to contractors from BIM

    Processes to develop a building model for contractors

    Design error detection and clash detection

    Quantity take-off and cost estimating

    Construction analysis and planning

    BIM and other management applications

    Offsite fabrication

    Use of BIM onsite

    Contract and organization changes

    29/07/2013 BIM for Contractors 6

    Information related to contractors from BIM Detailed building information

    An accurate 3D model to provide graphic views and to extract quantity and component property information

    Temporary components Equipment, formwork, and others for sequencing and planning

    Specifications associated with each component Cross-link to textual specifications for procurement, installation

    and commissioning

    Analysis data related to performance levels and project requirements Structural loads, heating and cooling loads, targeted luminance

    levels, etc. for procurement, fabrication, and MEP detailing

    Design and construction status To track and validate the progress of components relative to

    design, procurement, installing, and testing.

    Information related to operation for BOT contract29/07/2013 BIM for Contractors 7

    Agenda Types of construction firms

    Information related to contractors from BIM

    Processes to develop a building model for contractors

    Design error detection and clash detection

    Quantity take-off and cost estimating

    Construction analysis and planning

    BIM and other management applications

    Offsite fabrication

    Use of BIM onsite

    Contract and organization changes

  • 29/07/2013 BIM for Contractors 8

    A contractors building model from scratch Contractors to add additional, construction-specific

    information Either from 2D drawings or from a 3D geometric model

    Two levels of building models 3D only, no parametric components, for visual representation:

    clash detection, constructability review, visualization, and 4D sequencing

    Hybrid 3D/parametric model, for analysis and detailing

    29/07/2013 BIM for Contractors 9

    A contractors building model from BIM For non-BIM components

    Convert 2D drawing to BIM components in shared models Be very careful for model updates

    Changes made outside the model Version tracking

    29/07/2013 BIM for Contractors 10

    Agenda Types of construction firms

    Information related to contractors from BIM

    Processes to develop a building model for contractors

    Design error detection and clash detection

    Quantity take-off and cost estimating

    Construction analysis and planning

    BIM and other management applications

    Offsite fabrication

    Use of BIM onsite

    Contract and organization changes

    29/07/2013 BIM for Contractors 11

    Detection of clashes and design errors Type of clash

    hard clash: objects occupy the same space soft clash or clearance clash: objects are too close for

    adequate access, insulation, safety, maintenance, etc.

    The old days Overlay individual system drawings on a light table

    With CADD Overlay CAD layers in a 2D CAD system

    The drawbacks Visually and manually identify potential conflicts Slow, costly, error-prone (may overlook) Depend on the use of up-to-date drawings

  • Three different types of clash detection By visual check

    By checking physical spaces

    By rules

    29/07/2013 BIM for Contractors 12

    Building service system walk through

    29/07/2013 BIM for Contractors 13

    29/07/2013 BIM for Contractors 14

    Clash detection with 3D models and BIM 3D geometric models and BIM, are they different?

    3D geometric models: no semantics BIM: different levels of semantics and details

    Clash detection with 3D geometry Often return a large number of meaningless clashes

    A wall abutting another wall A pipe cutting through a wall

    Not good on non-solid objects Only detect clashes between surfaces

    Clash detection with BIM 3D geometry-based clash detection with semantics Selectively check clashes between specified systems

    For example, mechanical system and plumbing system Combined with rules to perform detection for soft clashes

    For example, the clearance between mechanical components and the subfloor is less than two feet

    29/07/2013 BIM for Contractors 15

    Requirements on BIM for clash detection A building model with an appropriate level of

    detail Have sufficient details for pipelines, ducts, structural

    components (concrete or steel), etc. Subcontractors to participate in the model

    development process as early as possible

    Multi-discipline coordination is desired Face-to-face meeting or Web conferencing Building models and different views to be displayed in

    front of each design team Agreed-upon-changes to be entered into the building

    model prior to the next clash detection run Dont ignore any minor change it may cause clashes

  • 29/07/2013 BIM for Contractors 16

    Two types of clash detection tools Clash detection within BIM design tools

    Available in most BIM authoring tools Allow quick clash detection during design

    Separate BIM integration tools to perform clash detection Used by contractors to integrate multiple design models Sophisticated to identify more types of soft and hard clashes Workflow is likely to be one way and not bidirectional

    Any identified clashes cannot be fixed immediately because the integrated model have no bidirectional path connected with the original models

    Examples Autodesks Navisworks Manage package Solibri Model Checker

    29/07/2013 BIM for Contractors 17

    Solibri Model Checker

    29/07/2013 BIM for Contractors 18

    Agenda Types of construction firms

    Information related to contractors from BIM

    Processes to develop a building model for contractors

    Design error detection and clash detection

    Quantity take-off and cost estimating

    Construction analysis and planning

    BIM and other management applications

    Offsite fabrication

    Use of BIM onsite

    Contract and organization changes

    29/07/2013 BIM for Contractors 19

    Quantity take-off and cost estimating Cost estimating in early design

    Cannot wait until the end of design work to get an estimate Parametric cost estimate: an approximate value in early design

    stage Based on major building parameters

    Parking garage: number of parking spaces Commercial building: number and area of each type of commercial

    space, number of floors, quality level of material A manual process: no definition about object types in some 3D

    sketching tools

    Cost estimating during design development Move the early design model into BIM software Capable to extract counts of components, area and volume of

    spaces, material quantities Define building models with appropriate level of detail

    Rebar in concrete footings or studs in walls Require early participation of GC and trade contractors

  • 29/07/2013 BIM for Contractors 20

    BIM not to replace estimators

    An estimators role Extract counts and measurements Assess conditi