If not a “return to normal” or the arrival of a “new normal”, 2021 brought another busy and record-setting year for Richard J. Driscoll, Consulting Engineer (RJDCE). The year was characterized by more regularity and fewer notable milestones. However, it set the stage for continued progress and perhaps some greater advancements in 2022. Continue reading “2021 Year in Review”
It is early in the investigation, of course, and as I have said before, it is not useful to attempt to draw conclusions immediately after a failure. Publicly available information is likely incomplete, may include imprecise or inaccurate information (there are slight discrepancies as to the time of the incident and early reporting identified the building as being three stories) and important details can get lost in the reporting process. More will be learned as the destroyed building is disassembled and removed. More yet will be learned in the course of the litigation that will inevitably follow. I do not have any answers, but I have a lot of questions. Continue reading “Should a Building Blow Down During Construction?”
To the uninitiated, a lot of everyday building construction with wood framing and concrete foundations looks pretty similar. However, from a structural engineering design perspective, they could be quite different. Light commercial and multifamily buildings, as well as some custom homes, are more complex and subject to greater load demands and code requirements than simple one- and two-family homes built using traditional practices documented in the residential code. It is normal for the construction documents for these projects to include structural engineering drawings to communicate to the contractor how engineered structural components and systems fit together.
In the residential and light commercial construction sector, some contractors do not seem to know what to do with structural drawings. The apparent similarity of these buildings to residential construction results in certain contractors attempting to serve both market segments, without understanding how they are different. Not knowing what they are taking on, they can be less expensive than their commercial/multi-family counterparts and are more likely to secure projects with inexperienced owners. This doesn’t always end well. Continue reading “Will Your Contractor Read the Drawings?”
Most excavations for building and bridge foundations, utility installation, site grading and other applications are made on relatively open sites with few constraints. These excavations are usually kept stable by cutting the sides on a stable. The geotechnical design of these temporary slopes is usually nothing more than conforming to prescriptive regulations from the Occupational Safety and Health Administration, which are applicable for depths of up to 20 feet.
Sloping the sides of an excavation effectively expands its footprint and site conditions may restrict the limits of the excavation on one or more sides. In developed areas, excavation limits are often restricted by property lines, utilities, contaminants, remnants of past structures and existing structures. When the depth of an excavation exceeds a nominal depth, and cutting the sides of the excavation at a safe slope is not practicable, the excavation sides must be supported structurally.
The presence of nearby existing in-service structures greatly increases the risk and technical difficulty of excavation. The most obvious example of this is excavating a basement on an urban lot with adjacent building foundations on the property lines bearing on soil above the bottom of the excavation. Underpinning of the adjacent structures is the norm in this scenario. However, nearby existing structures can present other difficulties that are less obvious and are unfamiliar to many in the construction industry. Continue reading “Unfamiliar Risks Excavating Near Existing Structures”
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.