Allegheny County Fire Academy

HOW THEY FAIL: GUSSET PLATES Behind the failure of many engineered structural elements lies the very instrument designed to hold them together. Engineered woo...d products, for the most part are composite structural elements, which rely on two or more separate materials to achieve strength and ultimately carry a design load. Many fire service professionals recognize Gusset plates in the field to readily identify that of such an engineered, or, lightweight structural element. We must discuss the dangers of these connections in a wood truss system, and the lessons learned that will provide a glimpse into experience based observations instead of relying on test methods within a controlled environment. Let’s take a look A Metal Plate Connector or Gusset Plate hails originally from Fort Lauderdale, FL in 1958. Originally dubbed Grip Plate for Truss they are a metal plate made of light gauge steel that is hydraulically pressed on one side forming small spikes or teeth on the other side. The teeth of the metal plate connector are about 1/4 to 3/8 inch. The plates are then secured by hand at first to truss members, and are then passed on to be secured by a hydraulic press. There is an allowance of a 1/8 max space between web and chord members. Experience has shown us that the weakest part of a wood truss is the connection, or panel point. This is where web members and chords meet by, you guessed it, the connection via a metal plate connector. They penetrate the wood fibers as previously said 1/4 to 3/8 inch. This connection is limited to the premise that there is no mishandling of the truss during transport and installation. Should a truss undergo a significant impact to the panel point and the penetrations are dislodged they cannot be set back in appropriately. It has been observed on one occasion that the metal plate connector that was dislodged was re secured with a inch steel staple. Metal Plate Connectors are made from galvanized light gauge cold formed steel. This type of steel experiences buckling and warping at 800 degrees. Following a recent fire, we looked at the conditions of a parallel chord wood truss floor system in the daylight. It was during this evaluation of structural integrity that we could draw certain conclusions based on real events. The Metal Plate Connectors were the weakest link in the truss system. Littered throughout the debris was hundreds of metal plate connectors, almost if it had been raining gusset plates. Fire damage to the trusses were significant. Charred trusses released the bottom chord once the metal plate connector dislodged and fell. The remaining metal plate connectors did not stay buried into the wood, they pulled away during the shifting of the floor system after multiple trusses had collapsed. On the contrary to many opinions including this authors, the metal plate connectors did not peel back, or warp, or bend. Once the wood surrounding and embedded into the plate connector burned, the plate fell off in one straight piece, and released its members, precipitating other plate failures. The rust on the galvanized plate indicates to us that it was superheated, ultimately deglazing the zinc coating. This is evidence to us of its conductive heat transmission into the wood. This supports the narrative of induced pyrolytic decomposition of the wood fibers of the truss from the metal plate connector’s teeth. Because the teeth of the metal plate connector were superheated and therefore conductively transmitted heat into the penetration, the teeth loosened and ultimately allowed the plate to fall. This disputes the theory that heat is reflected off of the plate, therefore benefiting the panel point. As you can see in the video provided, the top chord of the truss remained secured to the bottom of the second floor decking, due it its nailing from above. You can see a significant 10-12 inch deflection of the floor as well, with no structural integrity underneath. This also proves that due to massive tensile forces upon the bottom chord of the truss via fire damage, the metal plate connectors could not support the compression from above therefore releasing the plate, evidenced by teeth bent all in one direction. The trusses were found only ten minutes into the fire, and when communicated members evacuated the second floor, they opened a wall between the first and second floors and extinguished fire in the trussloft on one side of the house. What’s astonishing is that the post fire assessment showed this allowed the truss members to retain integrity, with little damage to the system, however once the heated metal plate connectors were quenched, there were a number of plates that pulled from their connection. Luckily, members were not on the second floor for long. Had the loading of multiple firefighters continued, including the static loading of water, it is obvious the floor would have collapsed completely. The trusses were free burning throughout the trussloft, and the first floor at times only had a haze, this is very dangerous. The Gypsum board prevented firefighters from seeing that structural compromise was so significant. It is truly a lesson learned. There are many factors that ultimately lead to the collapse of structural elements. Connections within engineered wood materials are the precipitating factor to the majority of such instances. Will a truss always collapse in 5-10 minutes, NO. But that’s not always what we are worried about. We should be concerned with the weakening of materials and connections such as with the metal plate connector that can mask a compromised structural system such as a truss floor, where the only precipitating factor needed to complete the collapse process is.us.

There has been a good bit of talk recently about balloon frame construction on some fire service related building construction social media sites. It fits in go...od with my previous posts about row houses. . In these images we see a house that was part of a row. The B exposure house was removed for some reason and a stucco or Dryvit style covering was placed over the party wall which is now an exterior wall. . Eventually it collapsed due likely to time, rot, workmanship and our ever-faithful friend gravity. A frustration for the building’s owners (Well maybe, who are they anyway, it’s hard to tell anymore, do they even know? Do they even care?). But it gave us a great opportunity to see a whole wall of balloon frame construction and some of the issues with it. . These images show two floors of balloon frame and one floor of some sort of platform construction. (Chime in if you have thoughts on the 3rd floors official construction type). . We can barely see the opening from the cellar into this space, but we can more clearly see the significant opening into the second-floor joist space. We can also see openings into the first and second floor cornices and the mansard void on the third floor. . The issue as always is that all of these voids are interconnected and allow for rapid fire extension vertically and horizontally on several levels. With these spaces being constructed of wood there is plenty of opportunity for preheating and significant, rapid fire spread. . Francis Brannigan, in his book Building Construction For The Fire Service, credits Augustine Taylor in 1833 for developing and using balloon frame construction for the first time. Because it was a lighter style of framing than was familiar, people said it would ‘blow away like a balloon.’ . The name stuck and so did this type of construction for roughly 100 years. There are plenty of these building remaining in their original or in some sort of modified or renovated state. Get out there and check them out, they can get you during a fire for sure! See more

Below is a list of classes offered in February. Please register ASAP if you are interested. https://www.alleghenycounty.us/WorkArea/linkit.aspx

Deadline extended!! We have extended our deadline until January 1,2021. If you are interested in a career with us please go to our website and take a look!

From Administrator Cook - Pennsylvania State Fire Academy COVID Update #10

The holidays are just around the corner! Check out the video below for safety tips you and your family should be following to stay safe this holiday season.

https://www.firefighterclosecalls.com/spectacular-conditio/

UPDATE: On December 29, 2020 at approximately 6:07 p.m., United States Marshals assigned to the West Virginia, Northern Office, Mountain State Fugitive Task For...ce captured Koby Francis at an apartment complex in Clarksburg, West Virginia. Francis will be housed at the North Central Regional Jail and Correctional Facility in Doddridge County, WV to await extradition. ORIGINAL POST: Allegheny County Police are searching for 22-year-old Koby Lee Francis of McKeesport. Francis shot a McKeesport officer shortly after 4 PM today and will be charged with criminal attempt (homicide), escape, flight to avoid apprehension, aggravated assault, and violation of the Uniform Firearms Act. Koby Francis is described as a black male, 6’2 tall with a thin build, having black hair and black eyes. He was last seen wearing a black hoodie, camouflage pants and black shoes with white soles. Anyone seeing him should contact 9-1-1 immediately. He is considered armed and dangerous. On December 20 at approximately 2:55 p.m., Francis entered the McKeesport Police station. He was served with a Protection from Abuse (PFA) order, after which he left the station. At 3:59 p.m., McKeesport Police were called to the 1500 block of Yester Square for a report of a PFA violation. When officers arrived, they observed Francis seated in a vehicle outside of the residence, a violation of the PFA order. Officers took Francis into custody at 4:04 p.m., seizing a firearm from the vehicle as well. Francis was combative upon arrest and during the transport to the McKeesport Police station. He kicked out a window of the car while being transported. Upon arrival at the station, the officer opened the door of the vehicle to remove the subject. When the door opened, Francis had a second firearm and shot the officer three times in the neck and torso. At 4:18 p.m., the McKeesport officer went on air and said that he had been shot. Video captured a minute later is of the subject fleeing on foot, still wearing handcuffs. Francis had been handcuffed with his arms behind him, but the video reflects that the handcuffs are now in front of him. The 32-year-old officer, a four-year veteran of the force, is in stable condition at a local trauma center. No other information, including his name, is being released at this time. The Allegheny County Police Department (ACPD) has assumed the investigation into the attempted homicide of the officer. The search for the subject continues at this time. In addition to the McKeesport Police Department and the ACPD, additional support has been provided by the surrounding municipal police departments, the Allegheny County Sheriff’s Office, the PA State Police, the Attorney General’s Office, the Pittsburgh Bureau of Police and federal agencies including ATF and the US Marshal’s Office. Anyone with information concerning this incident is asked to call the Allegheny County Police Tip Line at 1-833-ALL-TIPS (1-833-255-8477); callers can remain anonymous. The department can also be reached via its social media sites.

https://indd.adobe.com//80c0266e-82cc-4cc4-93db-5e1883a65e

The Allegheny County Fire Academy (ACFA) strives to provide the highest level of fire, rescue, hazardous materials and terrorism training to emergency service personnel and private industry emergency response teams. The courses and field exercises are designed to replicate real emergencies to ensure they have competent and prepared emergency response organizations. To learn more and see the 2021 training schedule, visit https://www.alleghenycounty.us///firefighter-training.aspx

Make it a fall back tradition! Change your clocks + change your alarm batteries this weekend. Working smoke alarms and carbon monoxide detectors save lives. M...ore tips: Install smoke alarms in every sleeping room, outside each separate sleeping area, and on every level of the home. A smoke alarm should be on the ceiling or high on a wall. Test all smoke alarms at least once a month by pressing the test button. It is best to use interconnected smoke alarms. When one smoke alarm sounds, they all sound. People who are hard-of-hearing or deaf can use alarms with strobe lights and bed shakers. Learn more: https://bit.ly/3mIscq5. #BeFireSafePA

https://youtu.be/lFqeBsMtXng

Talking about reading smoke, what would you teach your Probie about - Volume - Velocity - Density - Color... VOLUME - Large volumes of smoke generally indicate a larger fire. Volume sets the stage for Velocity. VELOCITY - Observe the speed of the smoke exiting the structure. The faster the speed of smoke the greater the pressure and the greater size of the fire. Velocity can indicate the volume and or heat of the fire. DENSITY - Smoke is generally denser, closer to the seat of the fire. Density can indicate the likelihood of an event (flashover, smoke explosion). It can also indicate the stage or degree of the fire. COLOR - Various products produce different colors of smoke. Take in mind though - it may not always indicate the true combustible burning. Some common agreements are Wood and Papers = Gray Smoke Hydrocarbons, Plastics = Black Smoke Nitrogen Oxides = Brown/Copper Smoke Steam = White Smoke Comment with anything else you'd like to add! . . Tag @trainyourprobie and use #trainyourprobie with your training and fire scene photos to be featured. Follow Us On FACEBOOK- Train Your Probie TWITTER- @trainyourprobie INSTAGRAM- @trainyourprobie #trainyourprobie #firefit #firetruck #firedepartment #fireman #firefighters #ems #firefighter #firefighting #technicalrescue #paramedic #firehouse #femalefirefighter #firedept #iaff #feuerwehr #crossfit #airborne #tacticalathlete #pompier #medic #hazmat #ambulance #bomberos #fdny #police #firerescue #wildland #firefighterfitness