Building construction- Masonry construction 25.2 questions and answers (verified for accuracy)

signs of pre 33 construction are? seismic upgrades, concrete caps on top of parapit walls, bond beams wherever trusses contact the exterior bearing walls, rater tie plates wherever floor joists or roof rafters (in those buildings with flat roofs) contact the exterior bearing walls. Other indicators are presence of sand lime mortar and "king rows" aka "header courses" placed usually every 7-11 row of stretcher course. Other features are thick walls resulting in recessed doors and windows and lentils over the doors and window openings Why is sand lime mortar dangerous? contains no concrete, and has lost its adhesion ability over time. Sand lime mortar scrapes away easily, and if determined sand lime mortar its automatically pre 33 Do seismic upgrades increase the buildings fire resistance? no, they only help with earthquakes. Some of these seismic upgrades actually make it more dangerous ( fire cuts) why are fire cuts in floor joist and rafters dangerous? theoretycally when the joist would collapse it would prevent the wall from coming down with the floor joist. But when the floor joist fail it causes enough force to push the walls outwards. what do rafter tie plates do? reinforce the connection between exterior bearing walls and the ends of floor joists or roof rafters. They decrease the risk that the exterior bearing walls will peel away from the building in a earthquake, resulting in roof and floor collapse. Where do you find rafter ties? They occur at REGULAR intervals along nearly the entire length of the bearing walls, at the same height the floor and or roof system connect to the bearing walls. danger to rafter ties? because of the strength of connection between the exterior bearing walls and the floor and roof system an inward collapse of exterior bearing walls is more likely how to distinguish tie ride and turnbuckles? same plate as rafter ties, but they occur at irregular intervals in the bearing walls and will almost always be located at heights other than floor or roof levels tie rods and turnbuckles are indicators that? building as already begun to collapse, unless associated with true bowstring truss or a lamella style roof "taxpayer" type construction residential units over commercial or mercantile occupancies in taxpayer construction, large windows in the front have large I beams supporting weight of wall above it, its important to? apply water to beam to cool to prevent collapse in taxpayer construction, the window with a beam is supported by two or most posts or columns which cause it to collapse outward in a 90degree angle instead of curtain fall which is normally related to masonry. This changes collapse zones, making you work from the flank positions . pre collapse indicators? creaking, rumbling sounds, cracked or bulging walls, cracks which continue to grow, water or smoke escaping through cracks, twisted or warped columns or beams, floor joist or roof rafters pulling out of their attachments, floors sagging/ pulling away from walls if collapse indications found? operations must be ceases until shoring can be placed If risky roof on a ribbed arch truss, where can you ventilate? place openings on "hip" sections on both ends if truss begins to fail? travel perpendicular to the truss back towards their escape route rather than towards the sidewall why are bowstring truss high risk? unprotected steal on the tie rode and turnbuckle. Failure time of approx 10 min. Should ventilate at hip sections Frank Brannigan rule? 10-20 percent of roof is damaged in a fire you should expect a complete roof collapse If a building has an arched roof without hip sections at each end it is normally a ? lamella roof reinforced blocks are every in reinforced masonry are usually every third cell true firewalls have? a parapet that extends at least two feet above the roof surface and one foot out from any sidewalls if the sidewalls are of combustible construction. They are required to be built to withstand collapse on pne side of the wall without affecting the structural stability of the structure on the other side Fire division walls? subdivide an occupancy into seperate fire zones, from foundation to roof, but lack parapet walls above the roofline or sidewall extensions. strength in these walls allow fire personnel to make defensive stands build up roofing fire ( on corrugated sheet metal roofs) should be suspected if large amount of smoke for little fire found. must apply water to roof. if tar droplets stops when water put on roof should suspect built up roofing fire what do you cut lightweight concrete roof with? carbide tipped blade on partner saw 3rd generation of tilt up structure roof secures the walls in place and the walls secure the roof in place. If either fails so does the other, like a massive house of cards If on panelized roof place ladder? 8 ft from any corner, should place the weight of ladder against a beam or purlin Anchor metal device use to hold down the ends of trusses or heavy timber members at the walls arch a curved structural member spanning an opening and serving as a support for the wall or the other weight above the opening bar joist a metal beam which is a parallel chord truss consisting of bar stock as a web member and angle iron for top and bottom chords Bowstring Truss a truss whose upper chords are curved or bowed and whose lower chord is straight, and does consist of a tie rod and turnbuckle assembly Chord Main members of trusses as distinguished from diagonals Course a horizontal layer of masonry. May be stretcher or header course Draft Curtain a noncombstible partition extending down from the ceiling to act as a barrier to the flow of heat Dropped ceiling A ceiling, which is hung or braced below, its supporting structure Fire cut an angled cut made at the end of a joist or wood beam, which is inserted into a masonry wall Fire wall a fire rated wall within a structure or between structures to impede the spread of fire. True firewalls have a parapet, which extends above the roofline and extend horizonatally beyond the exterior walls far enough to stop fire from extending horizontally from one subdivision or unit of the building to another. A fire rated, automatic closing door, must protect any opening in a firewall. Such closure mechanism may be fusible link / counterweight, or electro-magnetic type. True firewalls are also designed to withstand collapse on either side without affecting the structure integrity of the other side of the wall. Header A brick laid at right angles to the length of the wall in masonry construction (header coarse). In wood frame construction, the beam spanning over a door or window opening. Lateral Load A force applied to the side of a structural member Ledger Board a board nailed to studs or bolted to concrete wall slabs to support joist or rafters. Also known as a ribbon board Lintel A support for masonry over an opening, usually made of steel angles or other rolled shapes singularly or in combination. Similar to a "header" in wood frame construction Masonry The use of bricks, stones, concrete blocks or other units for construction Monolithic Consisting of one piece of stone or stone like material such as concrete. In monolithic frames, the frame is strong enough to withstand the loss of one structural element without causing failure of the structure. The resultant load is transferred to the other structural elements around the one that failed Mortar a mixture for bonding masonry units, usually of Portland cement, sand, lime and water. In pre 1933 masonry construction, little, if any cement was used Ordinary construction Construction using masonry walls, with other structural elements wholly or partly of wood Panel Points Points where the load of roof panels are transferred to trusses Parallel chord truss a truss whose upper and lower chords are parallel Parapet A low wall at the edge of a roof Party wall a bearing wall separating and supporting two adjacent buildings. While this wall can be used to make a defensive stand when fighting fire, it is not designed to with stand collapse, nor are openings protecting by fire rated assemblies as they are in a true firewall