Forensic Engineers and Consultants

Tag Archive: design safety analysis

  1. Installation of Structural Sheathing on Wood-Framed Structures

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    The facts presented in this blog lead to an interesting story.  During the heyday of the residential construction boom in coastal South Carolina circa 2005, many General Contractors were forced to go out-of-state to find framers and other subcontractors due to the demand creating a local labor shortage.  It turned out that the state of Texas had excess capacity and availability of framers and carpenters. Many Texas framing crews came to South Carolina to satisfy the shortage.  It soon became apparent that the Texas crews, many of which were from inland locations, were accustomed to installing 4’x8’ exterior wall sheathing with the long dimension vertical, i.e., parallel to the studs.  It is especially important and required that the long dimension be oriented perpendicular to the studs.  Laboratory testing has shown that (more…)

  2. Types of and Techniques for Reinforced Concrete Masonry Block Construction

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    Construction using concrete masonry blocks or units (CMU) is ubiquitous in the United States today, and in fact in the whole modern world.  CMU blockwork is a very versatile and relatively economical building material.  It is naturally strong in compression, but with reinforced, grout-filled cells, it can also withstand large shear, bending, and tensile loads imparted by lateral wind or seismic events.  In this article, I will discuss the various types of CMU designs, as well as terminology, construction techniques, and application uses.

    The design of CMU is typically comprised of hollow concrete “face shells” with (more…)

  3. Structural Issues with Coastal Residential Foundations

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    From corrosion to site drainage, coastal regions present a host of unique and challenging issues for homebuilders and residential property owners alike.  In this article, issues specific to coastal residential foundation installation and in-service function will be addressed.  “Coastal residential” will refer to single-family homes within AE or VE tidal flood zones for the purposes herein.  These locations typically exist in areas with close proximity to saltmarsh or beachfront, or on barrier sea islands.  Per FEMA, in AE zones, the elevation of the first finished floor must be above the flood elevation for the building site.  In VE zones, the elevation of the lowest horizontal structural member must be above the flood elevation for the site.  Most building jurisdictions also require a minimum of (1) foot of freeboard, or additional space, between the flood elevation and these building features.  As a result of these requirements, coastal residential structures must be supported by either crawl-space or elevated “drive-under” style foundations.  It should be noted that wall-type foundations are prohibited in VE zones, and structures within these zones are required to be supported by monolithic elements such as columns, piers, or piles.  Slab-on-grade type foundations are not permitted in flood zones where the foundation will exist within the flood plain. (more…)

  4. Stress Corrosion Cracking of Stainless Steel in Marine Environments

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    Stress corrosion cracking involves the slow growth of small, often microscopic, cracks through a metal part in a corrosive environment.  The cracking can continue to the point that the part fails suddenly and unexpectedly even though it still appears new and in good condition.

    My first experience with stress corrosion cracking happened in the Charleston harbor when the stainless steel rudder suddenly separated from a sailboat during moderate winds. What had been a pleasant evening sail turned instantly into being in a difficult to control boat in the middle of the busy shipping channel. The rudder remained attached only (more…)

  5. The Role of Interlocking Guards in Injury Prevention

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    In the three-part series on the CE mark, we scratched the surface of some of the requirements an equipment manufacturer must meet in order to earn this designation. Part three of the series dealt with some of the requirements for the design of a guard.  One of the items for consideration with the design of a guard is the frequency that someone will need to access the area protected by the guard.  If access is needed on a routine basis, often defined as more than once per shift, the guard needs to be designed to be movable instead of fixed.  Movable is defined as able to be opened without the use of tools.  Otherwise the frustration and time requirements of obtaining tools and removing a fixed guard will often lead to the guard being discarded. (more…)

  6. Don’t Get Burned With Your Gas Grill!

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    If there is one thing Americans can agree upon, it is the enjoyment that comes from an outdoor barbeque.  Whether a summertime cookout or a fall BBQ to watch a football game, we all love the fun and fellowship that comes from sharing a meal that was prepared outdoors on a grill or smoker.  In fact, 64% of Americans own a grill or smoker.  The great majority of these are LP fueled gas grills with comparatively few natural gas fired grills.  These products can be enjoyed safely when designed, installed, and used in a proper manner.  However, given the grill’s use of flammable fuel gas and high temperatures, the potential exists for things to go wrong and result in burn injuries or uncontained fires that spread to the surroundings. (more…)

  7. What’s Behind That CE Mark Part Three, Machine Guard Requirements

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    In the first blog in this series, we discussed the story behind the CE mark, the Machinery Directive, and the associated requirements regarding the design, production, and sale of machinery bearing the mark. The second blog discussed a cornerstone of safer machine design, the risk assessment. This installment will discuss another crucial piece of the safety puzzle, machine guard design. (more…)

  8. Working on the Waves While Working the Waves…

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    The rumors of my pending retirement have been greatly exaggerated…..

    Ever since I heard about The Great Loop I have wanted to cruise it (www.greatloop.org).  To successfully complete the Loop, one needs to have 3 things: adequate equipment, adequate time, and adequate health. I had the first and third.  To secure the second, I had floated the idea of a two-year sabbatical.  A year to complete any existing cases and a year to execute The Great Loop.

    With the arrival of COVID-19, our firm went to remote work. (more…)

  9. The CE Mark and What Should It Mean to You? Part Two

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    In the previous blog (Part One) we discussed the backstory behind the two stylized letters CE and what it means to the design of machinery bearing the mark.   We outlined some of the requirements of the “Machinery Directive” (MD) which include what are known as “Essential Health and Safety Requirements.” The Essential Health and Safety Requirements incorporate an iterative risk reduction process during design that takes into account (more…)

  10. Shedding Some Light on Fluorescent Light Fixture Fires

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    Lighting systems in buildings and other structures have undergone changes over the years.  Many of these changes have occurred as manufacturers have developed more efficient lighting methods.  Lighting loads can represent the largest category of electrical load in many buildings, thus improved lighting efficiency may significantly lower your power bill and can lengthen time between lamp changes. (more…)

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