Causes of Structural Failure
Bowstring trusses were used as the primary roof structural element from the 1920's through the early 1950's. Glued laminated beams replaced the wood trusses in the early 1950's, and are still a primary element in industrial and commercial buildings today. Tapered Steel Girders with rafters or a panelized roof deck were also very common in the mid 1950's and 1960's. There are many factors, which contribute to structural failures in these members. Some of the most common causes of horizontal framing members such as glued-laminated beam, roof trusses, purlins and rafter failures are:
Note: Because of
the large number of failures in these types of members over
the years, the current Uniform Building Code has reduced the
allowable values for fiber stress in bending in lumber, and
has introduced a volume factor. This new criteria provides
for a more accurate assessment of the true capacity of the
material used in glued laminated beams and wood roof
trusses, both in evaluating the capacity of an existing
member, and in sizing a new member.
Structural engineering is required for the repair of roof trusses, glued laminated beams and other horizontal framing members. The design and repair methods often vary, depending upon the individual condition or application. Broken beams can generally be repaired in place to carry full design loads, while overstressed members can be strengthened to support additional existing imposed loads.
SPS utilizes a variety of techniques to maintain a structurally sound, physically practical, and economically affordable repair. These techniques include the use of post-tensioning systems utilizing steel tension rods or high strength cables designed to increase the bending strength and the shear strength of the beam. Installation of shear dowels in epoxy-filled holes, installed vertically within.
On-site structural repair offers a number of advantages:
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Our Post-Tension System enables roof trusses and glued laminated beams to accommodate loads greater than the original design capacity. Structural reinforcement and repair can:
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