Innovative Materials and Techniques for Seismic Retrofitting
In the ever-evolving field of civil engineering, the drive to enhance and protect our built environment against natural calamities, particularly earthquakes, is of paramount importance. Innovative materials and techniques for seismic retrofitting have become a hot topic among engineers and scientists alike - and for good reason! These advancements not only promise increased safety but also ensure the longevity of structures in seismic zones. Firstly, let's dive into some of the groundbreaking materials that have been making waves (no pun intended) in the industry. Shape Memory Alloys (SMAs) are one such innovation that has caught many an engineer's eye. These alloys have this unique ability; when they're deformed during an earthquake, they can return to their original shape afterwards. It’s like magic - but it’s science! However, as with all new technologies, there are challenges to overcome – cost being a significant one. Another impressive material is Engineered Cementitious Composites (ECCs), also known as bendable concrete. This composite doesn't just crack under stress; instead, it stretches and bends, which can be incredibly useful during seismic events where rigidity often leads to failure. Yet again though (and it's quite a common theme here), affordability
read more →
Should I retrofit my house?
Share on social: if you live in one of the 16 states with the highest earthquake risk , it’s important to protect your investment and earthquake-proof your home. Houses built before 2000 don’t usually meet current seismic building standards. Unless you own a newly-constructed property, it’s a good idea to get your home retrofitted before an earthquake has a chance to strike. over the past few decades, there have been a number of devastating earthquakes across the world that have caused major structural damage to cities, homes, and individuals. Organizations such as earthquake country alliance have emerged in an effort to help protect people and property from earthquake damage. What is a cripple wall? Download pdf file10a. Anchorage for joists supported on concrete interior application 73. 69 kb download pdf file10b. Anchorage for joists supported on concrete interior or exterior application 57. 9 kb download pdf file11. Cripple wall bracing with plywood on exterior face of cripple studs 27. 92 kb download pdf file12. Single top plate splice 20. 56 kb download pdf file2a. Cripple wall section - parallel joists drawing 108. 51 kb download pdf file2b. Cripple wall section - parallel joists 128. 69 kb download pdf file3. Cripple wall
read more →
What About Older Buildings?
What About Older Buildin gs? These are structures that in crease resistance to the impact of an earthquake. Among the different methods are external post-tensioned metal straps that use precast concrete or the more conspicuous retrofittin g on the buildin g itself, in the form or massive columns or structures. This method is normally used on historical or older buildin gs that do not allow major in ternal refurbishments. The rostrevor house in wellin gton, new zealand uses this method to alleviate the effect of the 30,000 earthquakes of all magnitudes that the country experiences in each year. Can We Make These Buildin gs Safe? Seismic strengthenin g, seismic retrofittin g , and energy dissipation systems represent cuttin g-edge design strategies that have been successfully implemented to enhance the seismic resilience of numerous buildin gs. These in terventions are especially critical in earthquake-prone areas, where the structural in tegrity of buildin gs plays a pivotal role in ensurin g the safety and security of their occupants. Seismic strengthenin g in volves rein forcin g a buildin g’s existin g structure to withstand the forces exerted durin g an earthquake, min imizin g potential damage and reducin g the risk of collapse. Techniques can in clude the addition of steel braces and shear walls to provide additional lateral strength, base isolators to
read more →
Reinforced and unreinforced masonry
Experience from christchurch and overseas has shown that the failure of earthquake-prone buildings, or parts, can endanger lives. Thirty-nine people lost their lives when unreinforced masonry buildings failed during the christchurch earthquake on 22 february 2011. Earthquake risk reduction is a priority in new zealand. New zealand has had a progressive approach to improving standards for new buildings and earthquake-resistant design since design standards for buildings were first introduced into new zealand in 1935, following the napier earthquake. Advancements in the knowledge of seismicity, material properties and the response of buildings in earthquake shaking has resulted in progressive refinements to requirements for the design and detail of buildings. As a capstone to several mid-america earthquake center (mae center) projects, a full-scale two story unreinforced masonry (urm) building was tested following the application of several retrofit techniques, which included the use of fiber reinforced polymer (frp) overlays, near surface mounted (nsm) rods, vertical unbonded post-tensioning, and joist anchors. The test structure was composed of four urm walls, flexible timber diaphragms and interior stud walls, and was designed and built following construction practices consistent with those used in mid-america prior to 1950. Initial testing subjected both the roof diaphragm and in-plane
read more →
Shear failure within floor diaphragm
Diaphragms: floors and roofs can be used as rigid horizontal planes, or diaphragms, to transfer lateral forces to vertical resisting elements such as walls or frames. Shear walls: strategically located stiffened walls are shear walls and are capable of transferring lateral forces from floors and roofs to the foundation. Braced frames: vertical frames that transfer lateral loads from floors and roofs to foundations. Like shear walls, braced frames are designed to take lateral loads but are used where shear walls are impractical. Moment-resistant frames: column/beam joints in moment-resistant frames are designed to take both shear and bending thereby eliminating the space limitations of solid shear walls or braced frames. Foundation upgrades: strengthening the building’s foundation is fundamental to seismic retrofitting. This may involve adding new foundation elements or reinforcing existing ones to improve load-bearing capacity. Bracing systems: installing bracing systems, such as shear walls or diagonal braces, helps distribute seismic forces throughout the structure, preventing concentrated stress points that can lead to failure. Soft-story retrofits: multifamily buildings often have soft stories, typically ground floors with large openings like parking garages. Retrofitting these areas involves adding structural elements to enhance lateral stability. Damping systems: adding damping systems, such as base isolators or energy dissipation
read more →