THE STRUCTURAL materials of a building — whether it is made of wood, conerele, brick or masonry. steel or combinations of these - along with the reinforcing methods described in the fast “Quake Tips.” are significant factors in determin- ing the resistance to earthquake damage. QUAKE TIPS By Ross Peter72an Wood Frame Building By far, the most common build- ing type for single-family residences and low-rise commercial and apart- ment buildings (1-3 storey) on the North Shore is wood frame con- struction. Carefully designed and constructed, wood frame buildings have the greatest resistance to carth- quake damage of any type because of the lightness and Nexibility of the material and the resilience of the box frame components. The Jightness of wood means that the building's inertial load (when it resists the ground move- ment) is small, and as a result there is less tendency for it to move. The flexibility of wood and the box frame components gives the sup- porting elements (stud walls, columns) the ability to deform enough to avoid breaking or discon- necting. Because wood frame buildings are not as easily damaged by an earthquake, they are better able to withstand aftershocks; a feature not shared by more easily damaged building types such as brick or con- crete. Like other building types, wood frame buildings need a strong or sta- ble site, adequately connected foun- dation, adequate shear wall bracing and connected building elements, as required by the building code. Wood frame buildings with stucco walls or masonry veneer may lose these outer coverings if they are not well attached. Properly attached, Wood withstands quakes stugeo at least may increase the diagonal or racking strength of a wood frame building. Brick veneers have had a high failure rate in earth- quakes elsewhere because of poor mortar quality us well as poor con- nections to the wall, Because of the great weight of the brick or block masonry, inertial forces are high during an earthquake which can cause structural damage to the frame as well as the toss of facing. Even otherwise well-designed and well-built wood frame buildings can fail if their basic shear wall strength has been compromised by the creation of large openings for windows or garage doors. Most of the building faifures in the San Francisco Marina District in the 1989 earthquake were the result of such effects, Unreinforced Masonry Building Fortunately, there are few un- reinforced masonry buildings on the North Shore. These building types have a notoriously high failure rate in earthquakes, usually because they have little flexibility and once the building wall distorts much bey-.nd vertical, the mortar will fail, the bricks or blocks will break apart and the walls will collapse. When this happens, only an internal frame con- struction will keep the entire build- ing from collapsing. Importantly, several North Shore buildings which appear to be of unreinforced brick construction are actually wood or concrete frame buildings, with brick veneer of infill. Such buildings, including some of the older school buildings, may- survive quite well structurally in an earthquake although they could lose some of the brick veneer or infill. Filling the hollow centres of con- crete blocks with reinforcing steel and concrete can create a solid shear wall with considerable resistance to earthquake motion. The Northridge Calitornia earthquake in 1994 resulted in a collapse of many unre- The Opening of our new factory/showroom at 977 West Ist Street in North Vancouver. Here you will see the FLEXWOOD CUSTOM SLEEP SYSTEM, a revolutionary new custom designed European style bed engineered to provide lifelong comfort and healthful sleep. Like most bed systems, the FLEXWOOD CUSTOM SLEEP SYSTEM consists of two parts - the base and mattress - but here all similarities enci! We invite you to our factory /showroorn so you can see for yourself the comfort and quality of the FLEXWOOD CUSTOM SLEEP SYSTEM. LEXWOO ee =STOSS ahi 7 SSN TEND inforeed block walls. Siznif-icuntly, many walls with reinforcing steel ‘appeared to survive quite well, Reinforced Concrete Buildings Most large buildings on the North Shore, including high rise apartinents, office and commerciil buiidings, are of reinforced concrete coustruction, More recent: buildings with “ductile concrete” construction are highly earthquake resistant because of the Mexibility of the con- erete columns and other load bear- ing elements which will bend with- out fracturing. Because of the modu- lar type construction, it is critical that components of these buildings be adequately ded together, Some failures of these types of buildings in California were the result of improper joining of building com- ponents. A general rule might be that the newer the building, the See Steel page 19 That's because new DuPont Approved STAIVMASTER Plus™ offers longer-lasting stain and soil resistance—even after repeated professional cleaning. 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