Construction is a field with numerous specialties and specialists. As such, most construction projects require that the owner or developer assemble a team to ensure that people with the correct specialized knowledge and skill are available to complete the project. Most significant projects have two teams; one team designs the project while the other constructs it. Sometimes the lines between the design and construction teams blur, like when some portion of the design is delegated to the constructor.
For building projects, the design team is commonly assembled by the architect, while the construction team is assembled by the general contractor. Commonly, some, if not all, of the design team members are consultants to the architect. Architects know enough about the other disciplines like structural, mechanical and geotechnincal engineering, land surveying and interior design to be able to effectively engage those consultants and integrate their services into the overall design of the project. Similarly, general contractors have experience in subcontracting parts of the work that they do not self-perform and integrating the work of their subcontractors into the project. Continue reading “Your Building Project Needs an Architect”
The media coverage of a structural disaster is subject to a sort of “fog of war”. In the immediate aftermath, answers are hard to come by. Eye-witness and second-hand accounts, public records and other fragments of information are reported as news organizations receive them. Outside of trade and design professional publications, few media outlets have reporters specializing in construction and the built environment. As a result, reporting on structural failures is often poorly contextualized, contains misnomers and is framed by existing narratives like local government incompetence, “crumbling infrastructure” and effects of climate change, which may be more confusing than clarifying. Continue reading “Thinking About Structural Disasters”
“Geostrucutral engineering” is a term that has become increasingly common in the specialty foundation construction community in the past 10 to 15 years. Like too many terms in architecture, engineering and construction, it does not appear to have a consensus definition and may describe different things in different contexts.
If you search for geostructural engineering on the internet you would likely find marketing of particular collections of engineering services or perhaps an internal practice within a large multi-discipline firm. Some firms use “geostructural engineering” to mean geotechnical design, especially when advanced analytical tools are used. This appears to be a response to the use of “geotechnical engineering” to mean soil sampling and testing for engineering purposes without design services or even input into the design of a project. Other firms market services to construction contractors, including design and instrumentation and monitoring as “geostructural”.
Neither usage provides a clear meaning to the moniker, which leaves a lot of ambiguity as to what comprises the practice of geostructural engineering, how it is different from its parent geotechnical and structural disciplines, or other specialties therein, and the qualifications and body of knowledge required for geostructural engineers. Continue reading “What is Geostructural Engineering?”
Engineers and architects are sometimes asked by their clients if a conservative approach to design can be taken to reduce or eliminate the cost of professional services, especially the costs of specialists, advanced analysis and design methods, and explorations of existing structures and subsurface conditions. Ideally, the prime design professional, whether an architect, civil engineer or structural engineer, should understand what services add value to the project. Indeed sometimes the project is best served by making conservative assumptions or design decisions. For example, for wood-frame single-family dwellings and other light structures, it is often appropriate to design shallow foundations based on a minimal investigation and presumptive bearing capacity values in the code. Likewise, for relatively limited structural alterations, the impact of encountering unexpected conditions may not be enough to justify pre-construction exploratory demolition. In both cases, the incremental cost of investigation would not be expected to produce a commensurate benefit to the project and would represent a poor return on investment. The same logic applies to specialty professional services. All design decisions have trade-offs associated with them, but arbitrary conservatism in lieu of appropriate professional services is a misguided and in some cases, a risky strategy. Continue reading “Conservatism Cannot Substitute for Appropriate Services”
Strong demand for real estate purchases and renovation of existing buildings has resulted in a lot of recent calls for structural or foundation condition assessments. These engagements vary in scope depending on the purpose and the conditions to be assessed, but they typically involve a site visit followed by the issue of a report. Sometimes they are intended to assist the buyer of a property with due diligence either in response to an issue raised by an inspector or as a stand-alone structural condition survey. Sometimes they are to aid a seller in responding to a buyer’s concerns. Sometimes the purpose is to evaluate the cause of distress and to develop remedial options. And sometimes they function as feasibility studies for additions and other major alterations. Whatever the motivation, a portion of the increase in condition assessment calls has come from inexperienced prospects, some of whom have wildly unrealistic expectations. On multiple occasions, either during the initial call or after receiving the proposal, I have heard prospective clients express their assumption that the assessment they requested would require “just an hour or two” of professional services.
This assumption is wrong, of course, and reflects a common misunderstanding about how structural engineers solve problems. Much of the public, as well too many architects, civil engineers and contractors believe that structural engineers design from memory, like the general contractor on your favorite home improvement program who always knows what is and is not “code”. They expect the structural engineer to be able to look at a structure and make a pronouncement as to its adequacy on the spot like the contractor on television. Some do not understand the purpose of structural engineers at all since contractors supposedly have the same knowledge, but they can build the building as well.
Temporary structures are part of the means and methods of construction and can serve a variety of purposes. Some temporary structures are directly employed in the construction of a project; others provide access to work or protect works or the public from construction hazards.
The conventional wisdom in the construction industry is that temporary structures, regardless of purpose, are means and methods of construction and are the sole responsibility of the construction contractor. This responsibility extends to their design. Consequently, many construction industry stakeholders give little thought to how and by whom temporary structures are designed. ‘Let the contractor figure it out’ is a common attitude. However, this approach is too simple. While there are good reasons for the contractor to have responsibility for temporary structures, project stakeholders, including owners and their design professionals should recognize that they may have an interest in who designs the temporary structures used on their projects. Continue reading “Why Consulting Engineers Should Design Temporary Structures”
Ordinary construction projects usually follow some variant of one of two delivery methods: design-bid-build or design-build. In the design-bid-build delivery method, the owner retains design professionals to prepare construction documents, some form of competitive bidding process takes place, and the successful contractor builds the work. Most commercial building projects and a lot of public building and infrastructure projects use design-bid-build. In design-build, the owner, sometimes with the assistance of their design professionals negotiate an agreement with a constructor to design and build the project based on the owner’s performance criteria. The design-build method often reduces the duration of the project because construction can begin before the design is completed. It works well when the owner’s requirements can be well-defined and the details of the design are less important. Infrastructure projects, especially in the private sector, and home-building often uses design-build.
Despite the challenges presented by this strange, pandemic-impacted year, 2020 was a record-setting year for Richard J. Driscoll, Consulting Engineer (RJDCE), but also required resilience and adaptability.
The Year in Review
After record years in 2018 and 2019, RJDCE set records for proposals issued, new projects, hit rate, billings and revenue in 2020. Structural condition assessments, including forensic investigations, design for structural alterations, and claims/litigation support represented much of the practice’s work for the year. One highlight of the year was RJDCE’s involvement in the renovation of City Hall in Lebanon, New Hampshire for which RJDCE provided design of underpinning, sheeting and bracing, waterproofing and subslab drainage.
In populated areas, underground utilities are the lifeblood of the community. These utilities require periodic maintenance, expansions and replacement. Therefore, underground utility construction is common in cities, suburbs and rural villages alike.
Most people notice underground utility construction because of the traffic problems they may cause. However, if you are familiar with geotechnical or geostructural construction, you may have noticed poor or inconsistent risk management practices in the underground utility construction sector. Utility construction is not subject to the same type of codes and standards as buildings or transportation structures. Instead, the work may be governed primarily by the utility owner’s standards. Since the sophistication of utility owners can vary widely between a small-town water department and a major operator like ConEd or DC Water, the agency standards may vary widely from one owner to the next. Continue reading “Reducing Risk to Adjacent Properties from Underground Utility Construction”
A common application of underpinning is maintaining the stability of the foundations for adjacent structures during excavation on urban sites. If the excavation is deeper than the foundation depth for an adjacent structure, then the soil below the foundation could fail as the excavation proceeds, potentially causing the structure to collapse. Increasing the depth of an existing basement or cellar often requires underpinning to avoid similar foundation failures.
In these circumstances, concrete pier underpinning is typically employed. This technique became popular during subways construction in New York early in the twentieth century. The piers are constructed in a carefully staged sequence whereby a sheeted hand-excavated pit is advanced to the required depyh below a short segment of the existing foundation and is filled with concrete upon completion to create a pier. After load is transferred to the new pier, work can begin on an adjacent pier. Work continues until the entire foundation is resupported below the bottom of the excavation for the new structure. Then, excavation for the new structure can begin. In addition to transmitting loads to below the bottom of the excavation, the underpinning retains soil below the structure preventing soil below the building from being undermined.
While pier underpinning is common and well understood, it is a relatively expensive and high-risk type of construction. Sometimes adverse subsurface or site conditions, including access constraints, make pier underpinning difficult. This sometimes leads project stakeholders to seek alternatives. So what are the alternatives? Continue reading “What are the Alternatives to Pier Underpinning?”