Iano's backfill

BIM On the Construction Site

BIM, Beyond Clash Detection (www.constructech.com, March 29, 2011) provides an interesting discussion of recent trends in the intergation of building information modeling (BIM) with the construction process. Of particular interet to this author is the role of BIM in increasing the organization and efficiency of subtrade work, an aspect of building construction that lags behind many other industries.

Modular Schools

Back To School in Los Angeles,The Architect's Newspaper, 2/7/2011, reports on the Los Angeles Unified School District's recent selection of a modular, prefabricated system of building parts for the future design of schools ranging in size from 6000 to 30,000 sf in size. Using designs from local firms Hodgetts+Fung, Swift Lee Office, and Gonzalez Goodale, four or five facilities will be built, with more to follow if the initial results are satisfactory. The designs are purported to be inexpensive and quick to construct, easy to maintain, and--of course--sustainable.

Houses Fabricated to Order

Custom-Made House (MIT Spectrum, Winter 2011) reports on MIT Professor Larry Sass's efforts to industrialize the automated production of custom housing. In Sass's vision, prospective home owners would choose from house design options online. A computer driven process would then fabricate components to be delivered to the construction site. These precision-fitted could be assemblied without the need for nails or other mechanical fastners.

Related info:

• MIT Digital Design and Fabrication Group

The Delivery of Design and Construction Services

AGC-AIA Dispute Represents Deeper AEC/O Rifts (Cadalyst, Oct 25, 2007) discusses how changes in methods of project delivery, such as building information modeling, are leading to changes in the traditional roles of the designer and builder--changes that do not always come easily.

The upcoming 5th Edition of Fundamentals of Building Construction (due Fall of 2008) will have an expanded discussion of the roles of the building and construction manager in the construction of buildings.

More Info
Building Futures Council
The AGC's BIM Initiatives and the Contractor's Guide to BIM (AEC Bytes)

More Really Small Houses

HELP Is on the Way (Dwell Magazine, Feb/Mar 2006) describes  Architect Carib Daniel Martin and builder Rob Bragans' disaster relief  HELP (Housing Every Last Person) Housing  prototype.

Martin and Bragans' housing system is intended as a mass produced emergency housing system, and was designed in response to the plight of thousands of Gulf Coast residents left homeless by the hurricane disasters of 2005.

Digital Building Modeling & Facilities Design

Build It First Digitally (ENR, October 10, 2005) describes General Motors Corporation's use of 3-d digital modeling to fundamentally change the design and construction of two manufacturing facilities: the 2.4 million square foot Lansing Delta Township vehicle assembly plant and the 442,000 square foot addition to the Global V6 engine plant in Flint, Michigan.

In the case of the Flint plant, benefits attributed to the new techniques include a 24-week reduction in the typical 85-week construction schedule, completion of construction 5 weeks ahead of schedule, and zero change orders for building component interface conflicts (i.e., conflicts between piping, ductwork, structure, and other such elements). Michael Neville, vice president and project principal at Ghafari Associates, the architectural/engineering technology integrator on the project states, "In 26 years I have never seen a project run with more collaboration and be so simple."

According to ENR, the design process worked as follows: At the end of each week, updated design data was delivered from design subcontractors to the technology integrator. Over the weekend, this data was integrated into the shared building model, and collision detection routines were run to identify physical conflicts between elements. On Mondays, the design team would meet to review and resolve conflicts. (In initial runs, as many as 3000 collisions were detected.) Once design was complete and all conflicts resolved, the building model was "locked" and all parties agreed to construct the building according to the design model.

Other impacts of a building information model-centric design process included:

• Loosening of GM's traditionally rigid design software standards to accomodate the specialized building information modeling tools used on the project
• Elimination of paper progress submissions at 30%, 60%, and 90% design completion
• Use of the building model for the development of $5.5 million in value engineering savings at 90% completion of design
• Gains in construction efficiency with greater reliance on off-site prefabrication of assemblies, reduced construction waste, and reductions in on-site worker forces

Moving forward with future projects, GM predicts savings of 3% to 5% per project through elimination of systems interference alone, not including additional savings due to reduced construction time.

For more on related topics, see other articles in this site's Innovations In Building Design & Delivery category.

Portable, Inflatable Concrete Shelter

Need a Building? Just Add Water (Wired News, March 15, 2005) reports on the "Concrete Canvas", a portable, inflatable concrete shelter developed by UK Royal College of Art-Imperial College Masters students Peter Brewin and William Crawford. Brewin and Crawford's key development is a patent-applied-for, cement-impregnated fabric bonded to an inner inflatable membrane. In its portable form, the total package consists of folded fabric stored within a sealed plastic sack weighing 230 kilograms (507 lb).

Once delivered to the site, the structure can be erected by a single individual. The sack is filled with water--the sack being sized to ensure the proper water/cement ratio--and then inflated. After a twelve-hour setting period, the structure is ready for occupation and provides 16 square meters (172 square feet) of floor space.

Applications envisioned for the Concrete Canvas include emergency shelters for disaster recovery operations, aid agency activities, etc. Since the shelter can be delivered sterile, it can also support surgical operations not otherwise feasible in remote settings.

Innovations in Project Design & Delivery

The following surveys some recent articles covering trends in design and construction innovation. This author's overall impression: "one step forward, one step backward...":

Innovation In Design
Why Is Europe Winning? (Architecture, 02/2005) argues that cultural and professional differences between the US and Europe conspire to discourage innovation in building technology in the US relative to building design overseas. This provocative article points to factors such as:

• Differences in attitudes toward teamwork and cooperation
• European culture's greater respect for the work of its designers and engineers
• The litigiousness of the US business environment
• The confrontational relationships between the various parties to construction common in US project delivery methods
• Poor craftsmanship in the US building industry
• The higher proportion of building owner/occupiers in the European construction market

Among other ideas, the article makes a case for the use of the British quantity surveyor system in US construction. In one cited case, a quantity surveyor was hired by Rice University in Houston to analyze a project that was budgeted at $16.5 million but bid at $32 million. Based on the quantity surveyor's work, whose fees where roughly $25,000, the bid was reduced to $19 million.

The article ends on a pessimistic note, claiming that evidence points to a decrease in innovation on both sides of the Atlantic due to competitive and economic pressures.

No Easy Stamp of Approval (ENR, February 21, 2005) discusses the challenges in gaining code approval of innovative performance based designs when the codes themselves continue to rely on--and code officials continue to place their trust in--prescriptive methods. In theory, building designers and engineers have two options for complying with building code requirements: either meet the precise, prescriptive requirements of the the code, or, submit alternative, performance-based designs that can achieve the objectives of the code while relying on alternative methods. In practice, gaining regulatory approval of untested designs based on innovative and complex technical models is often an uphill battle.

[Author's comment: Performance-based approaches are most likely to be considered for large projects where the potential savings in construction cost or added value to be gained from improved building performance are sufficient to compensate for the added expense inherent in the development of such designs.]

The article leads off with the following response from San Diego building officials to structural engineers Magnessun Klemencic Associates (MKA), regarding their proposed structural design for a 460-foot tall San Diego highrise:

"Given the serious concerns we have regarding a structure of this height not have a dual lateral force-resisting system, we recommend against the designers proceeding with their proposed [performance-based] design. Instead, we suggest the designers follow code-prescribed methods."

In contrast, MKA's proposed alternative, performance-based design for the 450-foot tall IDX tower in Seattle, met with building department approval, and has been occupied since 2003. These two examples illustrate the difficulties and uncertainties that designers may face in taking such approaches.

This article goes on to discuss recent developments in the use of performance-based design for structural and fire-safety engineering, standards for the development of performance-based design, methodologies for the review of performance-based designs by regulatory authorities or peer-based committees, and the prognosis for future growth in the reliance on performance-based methods.

Intelligent Modeling
The Commoner's CATIA (Architecture, 12/2004) reports on Gehry Technologies recent release of its Digital Project software, a customized version of Dassault Systemes' CATIA 3-D Modeling software. According to the article, Gehry Technologies aims to provide a product that is both more useful to the architectural designer, and more affordable.

Go Direct-To-Fabrication, and Cut Out the Middleman, a related sidebar in the same issue, discusses trends toward the use of CAD/CAM applications to allow the direct translation of design models to fabrication processes. At the Fabrication conference, co-sponsored by the AIA and the Association for Computer-Aided Design in Architecture (ACADIA), participants could get hands-on practice with parametric CAD technology by SmartGeometry Group, as well as Bentley System's Microstration GenerativeComponents software outputting scale models directly to a laser cutter by Universal Laser Systems, a 3-D printer by Z Corporation, or a three-axis router by Techno-Isel.

Why building information modeling isn't working...yet (Architecture Record, 09.04) argues that while the concept that architects should rely on intelligent 3-d models of their work is at least 25 years old, it still isn't ready for prime time. This commentary piece is written by Ken Sanders, FAIA, a well-known prognosticator on the application of information systems in architectural practice.

Sanders argues first that the construction of buildings does not necessarily lend itself readily to the types of design and manufacturing processes used in the automobile or aerospace industries:

• Buildings are not easily transported from place of manufacture to point of sale.
• Buildings are constructed within a complex tangle of varying local and regional codes, regulations, and standards.
• Building construction cannot amortize design costs over large economies of scale as with mass-produced items.
• Buildings are rarely produced using an integrated design-build process.

Next, Sanders goes on to make the point that technology is not the key prerequisite to accelerating the trend toward use of building information modeling (BIM). Rather the key is more meaningful partnerships between the various parties to construction--the owners, designers, and builders. Without fundamental changes in these relationships, the potential value of BIM cannot be realized. Finally, the article concludes with a discussion of practical steps that can be initiated by the design and construction professions to further these goals.

Standards
AGC addresses document software interoperability (The Construction Specifier, December 2004) describes the Associated General Contractors of America's collaboration with Fiatech, a non-profit technical consortium, to develop XML standards for the enabling interoperability among construction management documents and systems. This news item also states that according to the National Institute of Standards and Technology, a lack of information interoperability costs general contractors $1 billion annually.

Congress Halts Metric Conversion Plans (Masonry Construction, February 2005) reports that the US Congress recently passed legislation stopping federal procurement policy that would have compelled the concrete masonry industry to manufacturer concrete masonry units to "hard" metric sizes for use in construction of federal facilities. According to the article, detractors claim that the change in size amounts to only a fraction of inch, but would require expensive retooling by most masonry manufacturers, and would lead to confusion in the marketplace as the newly-sized units would be visually indistinguishable from, but incompatible with, non-metric units.

Teamwork
The notions of teamwork and effective communicaiton as keys to technical success runs as a thread through much of the above. This sentiment is echoed by the editorial Paris Accident Shows the Need for More Team Building and the companion article, Airport Roof Failure Blamed on Process, (both in ENR, February 21, 2005):

"It seems that the industry must learn its harshest lessons...from disasters rather than in a measured way in classrooms, offices and labs. The partial collapse of the 640-meter long concourse at Paris Charles de Gaulle airport last May 23 should send a signal that there is a need for change in the French design process. The rest of the construction world should pay attention to the underlying principals of teamwork."

In this author's opinion, the more technically challenging the project, the more its success depends on the quality of the communication and collaboration among the parties involved in its design and construction.

Calatrava's Turtle Bay Sundial Bridge

What price beauty? According to Metropolis Magazine (Buying The Bridge, November 2004) the final cost for Santiago Calatrava's footbridge over the Sacramento River for the town of Redding, California was $23.5 million, far above the original $3 to $5 million budgeted for the project.

The bridge connects the city's Turtle Bay Museum with parkland on the river's opposite shore. The bridge's 700 foot long by 23 foot wide deck is supported by a sculptural, inclined steel pylon and 14 cable stays. The steel pylon was fabricated in Vancouver, Washington and shipped to the site in sections weighing 30 to 40 tons each. In order to minimize the bridge's environmental impact, it avoids setting foot in the river or even casting shadows into the river's sensitive salmon spawning grounds. Yet the pylon does function as a sun dial, casting its shadow onto the large plaza formed at its base.

According to Modern Steel Construction's Sun Sculpture (October 2004), the project was not just a financial challenge for the client, but also a constructional challenge. The project required approximately 500 construction drawings to be completed by the construction team based on preliminary design drawings provided by Calatrava. This documentation work included:

• 3-d modeling of the original design
• Sophisticated mathematical adjustment of the 3-d model providing cambering to counteract dead and live loads on the structure
• Development of detailed descriptions of each of more than 1200 steel plates, including different angle cuts on each edge in preparation for full-penetration welding to adjacent plates
• Preparation of several scale models and an animation to assist with visualization of the bridge and its construction sequencing

Complicating this work was the fact that the pylon is a double-walled structure, with the non-parallel inner and outer walls. Detailing took almost 2 years to complete.

Developments In Low-Cost Residential Construction

ICF Homes
Concrete Homes Continue to Rule The Roost in Lubbock, Concrete Homes Newsletter, May/June 2004, describes the City of Lubbock, Texas's ongoing efforts to replace substandard and deteriorating homes with new homes built with insulating concrete form (ICF) construction.

The replacement program is part of the city's Affordable Housing Reconstruction Program, which receives funding from federal, state, and private sources. According to the article, ICF constructed homes have proven so energy efficient and disaster resistant that the city no longer accepts bids for conventional wood-frame constructed homes.

NAHB Demonstration Homes
Houses M.A.D.E. for research, Fine Homebuilding, July 2004, describes the National Association of Home Builder's (NAHB) four demonstration houses constructed using materials and methods highlighted in NAHB's 1999 Builder's Guide to Marketable, Affordable, Durable, Entry-Level Homes to Last (MADE).

Innovations demonstrated in these projects include:

• precast concrete foundation walls
• advanced framing methods
• maintenance-free siding and roofing materials
• air-admittance valves (mechanical venting ports used in a plumbing system to eliminate conventional pipe venting)
• CPVC plastic water piping
• standing seam metal roofs
• high-efficiency floor plans

Prefabricated Homes
Factory-Built Houses, Fine Homebuilding, June/July 2004, compares pros, cons, and costs of three types of prefabricated home construction technologies: panelized, modular, and structurally insulated panels (SIPs).

For each technology, this full-length article describes the basic systems involved, describes the building process with first-hand accounts and annotated photographs, and provides brief lists of pros and cons. The challenges in attempting to create apples-to-apples cost comparisons between the three technologies are also discussed. Some bottom-line conclusions include:

• Panelized construction offers shortened construction time with few if any limitations on design flexibility.
• Modular construction offers the shortest construction time and greatest potential costs savings, but is more limited in design flexibility. (Except for connecting plumbing, electric, and laying carpet, a house can be erected in as little as one day.)
• SIPs construction offers high energy efficiency and high structural strength, but at higher costs than the other systems featured in this article.

More Info
_For additional articles on Lubbock's ICF home building program see Lubbock emerges as frontrunner in concrete home construction, and Rebuilding a Community with Strong, Energy Efficient, Affordable Homes.
_More information on MADE homes is available at Results from the Field: MADE Project Path Field Evaluation Site.
_For more articles on this site related to innovative construction technologies see this site's innovations in project design & delivery category. For another example of modular construction aspiring to quality design and environmental friendliness not previously mentioned on this site, see also The Glidehouse by mkarchitecture.