The Role of Structural Inspectors
Structural inspectors for seismic retrofit are not exactly the same as structural engineers and are sometimes confused, although they share certain common tasks. While some contractors want structural inspectors to have engineering backgrounds, many inspectors get their training on the job. The state where the inspection takes place defines the qualifications for structural inspectors.
Checking the Foundation and Floors
Looking for cracks and other problems with a building’s foundation, floor, walls, ceiling and roof characterize the main role of a structural inspector. His or her goal is to identify structural issues associated with aging or perhaps poor installation. The inspector’s job is to be objective and to assess the health of the property from its foundation to the roof to determine if retrofit work is needed.
The inspection process begins with studying the foundation and checking to see how the structure connects with it and whether or not it’s securely bolted down. It’s imperative that the building is built on a solid foundation to avoid movement, which can lead to cracks throughout the structure.
When the ground floor is not level, it’s an indicator of vertical movement. Soft soil can also cause movement. A building with pillars or concrete steps that has experienced vertical movement may show cracks in the respective structures. Separation cracking is a type of cracking that reveals which direction the structure is moving. When the main part of a building begins pulling away, it’s a sign that retrofit is necessary.
Looking for Cracks Throughout the Building
Structural inspectors look for cracks throughout the building, but particularly around doors and windows, which are the weakest points in a foundation. Vertical cracking in the drywall or when the baseboard becomes detached from the wall also indicate movement in the foundation. Meanwhile, a sagging roof indicates structural movement.
Determining Retrofit Work
The inspector takes notes that will become part of a detailed report for the building owner. After analyzing the entire building, the contractor determines what type of retrofit work is needed to make the building safer for occupants.
Several retrofit strategies based on the building’s existing structure are used to strengthen it to withstand seismic activity. Concrete Tilt-Up and Reinforced Masonry (CMU) are buildings which may need roof to wall anchors and continuity ties so that the roof does not fall apart during a strong earthquake. Un-reinforced Masonry (URM) is a type of building that needs roof to wall connectors, continuity ties and a new plywood overlay for the roofing.
Soft-story buildings typically have an open first floor, comprising of a garage with apartment or office units on top. These buildings can be extremely vulnerable during a quake. Sometimes it takes steel framing or concrete footing to strengthen these structures.
Retrofit specifications begin to take shape following a thorough structural inspection of a building. Contact us at Saunders Construction to learn more about making your building safer so that your tenants feel more at ease and are protected from natural disasters.