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  • Lessons Learned fromLessons Learned from Structural Engineers Learning g g

    the Hard Way

    for SEAoT State ConferenceSEAoT State Conference

    September 28, 2012

    Presented by Davy Beicker PE RMTPresented by Davy Beicker, PE, RMT

  • Lesson 1:P f b i t d W d TPrefabricated Wood Trusses

    Project Description: Roof framing using prefabricated 4x2 wood g g p

    trusses 24 inches on center.

  • Lesson 1:P f b i t d W d TPrefabricated Wood Trusses

    Structural Engineer of Record Involvement: Provided design requirements for trussesg q Provided layout of trusses Checked specialty engineers design calculationsp y g g Checked to see that Fabricator was certified by

    TPI Visited the site to check construction of the

    trusses

  • Lesson 1:P f b i t d W d TPrefabricated Wood Trusses

    Specialty Engineer Involvement: Provided truss design calculations g Provided layout of trusses Fabricator was certified by TPIy Provided the first set of truss repair plans

  • Lesson 1:P f b i t d W d TPrefabricated Wood Trusses

    What was Discovered? During a visit to the site, the Structural Engineer g g

    noticed some truss members were damaged and he thought needed repair.

    SE requested another engineer review the structural condition of the trusses and design a

    i f h d d ditirepair for each damaged condition.

  • Lesson 1:P f b i t d W d TPrefabricated Wood Trusses

    What was Discovered? At first, the fabricators engineer designed some g g

    repairs but then would not come to the site to check if the repairs were performed. (He was th t f t t)the out-of town expert)

    A local engineer was then hired to inspect the repairs.

  • Lesson 1:P f b i t d W d TPrefabricated Wood Trusses

    What Else was Discovered? Truss metal connection plates were poorly p p y

    installed on the trusses. Some (around 500) missed the truss member.

  • Lesson 1:P f b i t d W d TPrefabricated Wood Trusses

    Plates missed panel pointsPlates missed panel points

    Knot good

  • Lesson 1:P f b i t d W d TPrefabricated Wood Trusses

    What Else was Discovered? Broken and Knotty boards were used. y

  • Lesson 1:P f b i t d W d TPrefabricated Wood Trusses

  • Lesson 1:P f b i t d W d TPrefabricated Wood Trusses

  • Lesson 1:P f b i t d W d TPrefabricated Wood Trusses

    What Else was Discovered? Heavy sprinkler pipes were hung from the wrong y p p p g g

    place of the truss.

  • Lesson 1:P f b i t d W d TPrefabricated Wood Trusses

  • Lesson 1:P f b i t d W d TPrefabricated Wood Trusses

    What Else was Discovered? A roof hatch opening was not framed out.p g

  • Lesson 1:P f b i t d W d TPrefabricated Wood Trusses

    What Did We Learn? SER site observations are important. p SER needs to know what he is looking for. Special inspections would not have discovered p p

    any of this.

    End of Lesson 1

  • Lesson 1:P f b i t d W d TPrefabricated Wood Trusses

    Questions?

  • Olmos Dam 1998Take unexpected loads seriously

  • Lesson 2:B ilt W d TBuilt-up Wood Trusses

    Project Description: The homeowner wanted an unusual shape truss p

    he found in a magazine. The truss builder insisted that the truss and connections be d i d b i d t th l k fdesigned by an engineer due to the lack of a continuous bottom chord.

  • Lesson 2:B ilt W d TBuilt-up Wood Trusses

  • Lesson 2:B ilt W d TBuilt-up Wood Trusses

    The Engineer designed the 40 ft trusses using RISA with concealed steel plates between the wood members. The truss builder built them in his shop and then sent them to the site.

  • Lesson 2:B ilt W d TBuilt-up Wood Trusses

  • Lesson 2:B ilt W d TBuilt-up Wood Trusses

    After the trusses were erected, the erecter noticed about a 1 inch sag in all the trusses. The engineer visited the site (120 miles round trip). Someone had added a notch in(120 miles round trip). Someone had added a notch in the top chord of the trusses. The engineer believed the reduced size of the compression top chord accounted for some of the unexpected amount of deflection.some of the unexpected amount of deflection.

  • Lesson 2:B ilt W d TBuilt-up Wood Trusses

  • Lesson 2:B ilt W d TBuilt-up Wood Trusses

    The roof joists were installed and the trusses sagged an additional inch. The engineer visited the site again and took more measurements and reviewed the trusstook more measurements and reviewed the truss construction, erection and his design closer. He hired his engineer buddy to check his design. (because that is what an engineer buddy does)what an engineer buddy does)

  • Lesson 2:B ilt W d TBuilt-up Wood Trusses

  • Lesson 2:B ilt W d TBuilt-up Wood Trusses

    His buddy engineer confirmed that the design was not the problem. Something was apparently not built right. The engineer prepared plans to repair the truss by addingengineer prepared plans to repair the truss by adding new exterior steel plates, additional bolts and epoxy filling bolt holes and ridge beam gaps.

  • Lesson 2:B ilt W d TBuilt-up Wood Trusses

  • Lesson 2:B ilt W d TBuilt-up Wood Trusses

    The new plates were fabricated and sent to the site. The engineer visited the site again to review the repairs. At this site visit he learned that all the bolt holes were overthis site visit he learned that all the bolt holes were over-bored 1/8 inch bigger than the bolt diameter in both the wood members and the steel plates rather than 1/16.

    The schedule was getting behind and the homeowner was getting more and more upsetgetting more and more upset.

  • Lesson 2:B ilt W d TBuilt-up Wood Trusses

    The engineer also discovered that the bolts used did not have enough thread and couldnt be tightened The bolts would spin in the holestightened. The bolts would spin in the holes. Since the plates added an additional inch of thickness they could be reused.thickness they could be reused.

  • Lesson 2:B ilt W d TBuilt-up Wood Trusses

    The bolts were removed, the new plates were added, the trusses were shored into position, the holes were epoxy-filled the same bolts were tightened because the newfilled, the same bolts were tightened because the new side plates helped the thread problem. Shores were removed and the trusses held in place.

  • Lesson 2:B ilt W d TBuilt-up Wood Trusses

    The homeowner was not thrilled about the exterior plates but decided they were acceptable.

    The home builder, the engineer and truss builder were lucky there was not a lawsuit. The homeowner was an attorneythere was not a lawsuit. The homeowner was an attorney but diligent and proactive work by everyone to get the problem resolved prevented the situation from escalating.

  • Lesson 2:B ilt W d TBuilt-up Wood Trusses

    Some Lessons Learned:Look at all possibilities that could have an impact on your

    d i D t f t b t thi lik id bdesign. Dont forget about things like a ridge beam.

    Think about adding camber in the designThink about adding camber in the design.

    Find out if your owner is a snake lawyer. y y

  • Lesson 2:B ilt W d TBuilt-up Wood Trusses

    The Bigger Lesson Learned:Be diligent when there is a problem and work to solve it first,

    th b t tti id if it i t d tthen worry about getting paid if it is not due to your errors. Even if you are right, everyone gets named in a lawsuit and the only winners are the lawyers. y y

    The owner did not pay any for all the extra pain and ff i b th i th b ildsuffering by the engineer or the builder.

    The home builder is still the engineers clientThe home builder is still the engineer s client.

  • Lesson 2:B ilt W d TBuilt-up Wood Trusses

    Special Inspections may have avoided the problem with the oversize holes and wrong length bolts.

  • Lesson 2:B ilt W d TBuilt-up Wood Trusses

    SEAoT provides a great resource to meet other engineers. An outside design check by an engineer you trust and you know is competent can be beneficial if everythingyou know is competent can be beneficial if everything goes South.

    If there is a problem with your design, you have an ally in being pro-active on a repair. The engineer let everyone know that he retained another engineer to review hisknow that he retained another engineer to review his design. This kept others from finding an engineer that may not be interested in resolving the situation.

    End of Lesson 2

  • Lesson 2:B ilt W d TBuilt-up Wood Trusses

    Questions?

  • R B li (St ll ) i t t l i h i lRay Breslin (Stallone) is a structural engineer who is wrongly convicted of a crime. Breslin designed a variety of high tech buildings and was a top structural engineer. After Breslin was wrongly convicted, he was sent to serve his sentence in a o g y co cted, e as se t to se e s se te ce amaximum security prison of his own design. During his time in prison, Breslin has analyzed every high security prison and gained significant survival skills, but faces his biggest challenge in trying to break out of an ultimate high tech prison that he himself designedbreak out of an ultimate high-tech prison that he himself designed to be escape-proof.

  • Lesson 3:Tilt W ll P l E b d Pl tTilt Wall Panel Embed Plates

    Embed plates have to fit in the wall panel along with all the reinforcing steel.

  • Lesson 3:Tilt W ll P l E b d Pl tTilt Wall Panel Embed Plates

  • Lesson 3:Tilt W ll P l E b d Pl tTilt Wall Panel Embed Plates

  • Lesson 3:Tilt W ll P l E b d Pl tTilt Wall Panel Embed Plates

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