What features help a building withstand an earthquake

what features help a building withstand an earthquake

These 7 quake-resistant buildings are designed to withstand the next big shockwave

During an earthquake or high winds, the pendulum counteracts the buildings movements. In , during Typhoon Soudelor, Taipei was blitzed with winds of miles per hour and even a gust. Nov 20, How to design earthquake proof buildings. A bottleneck that most structural engineers face when designing buildings in earthquake-prone areas is the vagueness of just how earthquake-proof the prospective structure should be; this is because earthquakes vary in magnitude and causes, ranging from deep openings in the earths surface to severe disturbances across a fault line.

The San Fernando earthquake also known as the Sylmar earthquake occurred in the early morning of February 9 in the foothills of the San Gabriel Mountains in southern California. The unanticipated thrust earthquake had a magnitude of 6. The event was one in a series that affected Los Angeles county in the late 20th century.

Damage was locally severe in the northern San Fernando Valley and surface faulting was extensive to the south of the epicenter in the mountains, as well as urban settings along city streets and neighborhoods. Uplift and other effects affected private homes and businesses. The event affected a number of health-care facilities in SylmarSan Fernandoand other densely populated areas north of central Los Angeles.

The Olive View Medical Center and Veterans Hospital both experienced very heavy damage, and buildings collapsed at both sites, causing the majority of deaths that occurred. The buildings at both facilities were constructed with mixed styles, but engineers were unable what is a contractor license number thoroughly study the buildings' responses because they were not outfitted with instruments for recording strong ground motionand this prompted the Veterans Administration to later install seismometers at its high-risk sites.

Other sites throughout the Los Angeles area had been instrumented as a result of local ordinances, and an unprecedented amount of strong motion data was recorded, more so than any other event up until that time. The success in this area spurred the initiation of California's Strong Motion Instrumentation Program. Transportation around the Los Angeles area was severely afflicted with roadway failures and the partial collapse of several major freeway interchanges. The near total failure of the Lower Van Norman Dam resulted in the evacuation of tens of thousands of what to buy at wholefoods residents, though an earlier decision to maintain the water at a lower level may have contributed to saving the dam from being overtopped.

Schools were affected, as they had been during the Long Beach earthquakebut this time amended construction styles improved the outcome for the thousands of school buildings in the Los Angeles area. Another result of the event involved the hundreds of various types of landslides that were documented in the San Gabriel Mountains. As had happened following other earthquakes in California, legislation related to building codes was once again revised, with laws that specifically addressed the construction of homes or businesses near known active fault zones.

The San Gabriel Mountains are a The domain of the ranges stretches from the Channel Islands offshore to the Little San Bernardino Mountainsmiles km to the east. The frontal fault system at the base of the San Gabriel Mountains extends from the San Jacinto Fault Zone in the east to offshore Malibu in the west, and is defined primarily by moderate to shallow north- dipping faults, with a conservative vertical displacement estimated at 4,5, feet 1,1, m.

Paleomagnetic evidence has shown that the western Transverse Ranges were formed as the Pacific Plate moved northward relative to the North American Plate. As the plate shifted to the north, a portion of the terrane that was once parallel with the coast was rotated in a clockwise manner, which what are the factors of 664 it positioned in its eastwest orientation.

The Transverse Ranges form the perimeter of a series of basins that begins with the Santa Barbara Channel on the west end. A small number of damaging events have occurred, with three in Santa Barbara, and and two in the San Fernando Valley andthough other faults in the basin that have high Quaternary slip rates have not produced any large earthquakes.

The San Fernando earthquake what can non members buy on club penguin on February 9,at am Pacific Standard Time UTC with a strong ground motion duration of about 12 seconds as recorded by seismometers, [10] although the whole event was reported to have lasted about 60 seconds.

Considerable damage was seen in localized portions of the valley and also in the foothills of the San Gabriel Mountains above the fault block. The fault that was responsible for the movement was not one that how to use us ip address in india been considered a threat, and this highlighted the urgency to identify other similar faults in the Los Angeles metropolitan area.

The shaking surpassed building code requirements and exceeded what engineers had prepared for, and although most dwellings in the valley had been built in the prior two decades, even modern earthquake-resistant structures sustained serious damage. Several key attributes of the event were shared with the Northridge earthquakeconsidering both were brought about by thrust faults in the mountains north of Los Angeles, and each resulting earthquake being similar in magnitude, though no surface rupture occurred in Since both occurred in urban and industrial areas and resulted in significant economic impairment, each event drew critical observation from planning authorities, and has been thoroughly studied in the scientific communities.

Additional breaks occurred farther to the east that were in a more scattered fashion, while the western portion of the most affected area had less pronounced scarps, especially the detached Mission Wells segment. Although the complete Sierra Madre Fault Zone had previously been mapped and classified by name into its constituent faults, the clusters of fault breaks provided a natural way to identify and refer to each section. As categorized during the intensive studies immediately following the earthquake, they were labeled the Mission Wells segment, Sylmar segment, Tujunga segment, Foothills area, and the Veterans fault.

All segments shared the common elements of thrust faulting with a component of left-lateral slip, a general eastwest strikeand a northward dip, but they were not unified with regard to their connection to the associated underlying bedrock.

The initial surveyors of the extensive faulting in the valley, foothills, and mountains reported only tectonic faulting, while excluding fissures and what makes a good t shirt features that arose from the effects of compaction and landslides.

In the vicinity of the Sylmar Fault segment, there was a low possibility of landslides due to a lack of elevation change, but in the foothills and mountainous area a large amount of landslides occurred and more work was necessary to eliminate the possibility of misidentifying a feature. Along the hill fronts of the Tujunga segment, some ambiguous formations were present because some scarps may have had influence from downhill motion, but for the most part they were tectonic in nature. In repeated measurements how to give yourself a buzz cut the different fault breaks, the what features help a building withstand an earthquake remained consistent, leading to the belief that most of the slip had occurred during the mainshock.

While lateral, transverse, and vertical motions were all observed, the largest individual component of movement was 5 ft 3 in 1. The largest cumulative amount of slip of 6 feet 7 inches 2. Analysis revealed that the earthquake triggered over 1, landslides.

Highly shattered rock was also documented along the ridge tops, and rockfalls which continued for several what features help a building withstand an earthquake were the result of both the initial shock and the aftershocks. Few of the slides that were logged from the air were also observed from the ground. The greatest number of slides were centered to the southwest of the mainshock epicenter and close to the areas where surface faulting took place.

The slides ranged from 49 feet 15 m in length, and could be further categorized as rock fallssoil falls, debris slides, avalanches, and slumps. The most frequently encountered type of slide was the surficial less than 3 feet 0.

In earlythe San Fernando Valley was the scene of a dense network of strong-motion seismometers, which provided a total of seismograms. This made the earthquake the most documented event, at the time, in terms of strong-motion seismology ; by comparison, the Alaska earthquake did not provide any strong motion records. Part of the reason there were so many stations to capture the event was a ordinance that required newly constructed buildings in Beverly Hills and Los Angeles over six stories in height to be outfitted with three of the instruments.

This stipulation ultimately found its way into the Uniform Building Code as an appendix several years later. One hundred seventy-five of the recordings came from these buildings, another 30 were on hydraulic structuresand the remainder were from ground-based installations near faults, including an array of the units across the San Andreas Fault. The instrument that was installed at the Pacoima Dam recorded a peak horizontal acceleration of 1. The extraordinarily high acceleration was just one part of the picture, considering that duration and frequency of shaking also play a role in how much damage can occur.

The accelerometer was mounted on a concrete platform on a how much does it cost to get at shirt printed ridge just what are the two chambers of congress one of the arch dam 's abutments. Cracks formed in the rocks and a rock slide came within 15 feet 4.

As a result of what was considered a fortunate accident, the machine kept recording for six minutes until it ran out of paper and provided scientists with additional data on 30 of the initial aftershocks. The areas that were affected by the strongest shaking were the outlying communities north of Los Angeles that are bounded by the northern edge of the San Fernando Valley at the base of the San Gabriel Mountains.

The unincorporated districts of NewhallSaugusand Solemint Junction had moderate damage, even to newer buildings. The area where the heaviest effects were present was limited by geographical features on the three remaining margins, with the Santa Susana Mountains on the west, the Santa Monica Mountains and the Los Angeles River to the south, and along the Verdugo Mountains to the east.

Loss of life that was directly attributable to the earthquake amounted to 58 a number of heart attacks and other health-related deaths were not included in this figure. Most deaths occurred at the Veterans and Olive View hospital complexes, and the rest were located at private residences, the highway overpass collapses, and a ceiling collapse at the Midnight Mission in downtown Los Angeles.

The damage was greatest near and well north of the surface faulting, and at the foot of the mountains. The hospital buildings, the freeway overpasses, and the Sylmar Juvenile Hall were on coarse alluvium that overlay thousands of feet of loosely consolidated sedimentary material. In the city of San Fernando, underground water, sewer, and gas systems suffered breaks too numerous to count, and some sections were so badly damaged that they were abandoned.

Ground displacement damaged sidewalks and roads, with cracks in the more rigid asphalt and concrete often exceeding the width of the shift in the underlying soil. Accentuated damage near alluvium had been documented during the investigation of the effects of the Santa Rosa earthquakes. A band of similarly intense damage further away near Ventura Boulevard at the southern end of the valley was also identified as having been related to soil type.

Federal, county, and private hospitals suffered varying degrees of damage, with four major facilities in the San Fernando Valley suffering structural damage, how to tell bumblebee from carpenter bee two of those collapsing. Nursing homes also were affected. The one-story Foothill Nursing Home sat very close to a section of the fault that broke the surface and was raised up three feet higher than the street.

Scarps ran along the sidewalk and across the property. The building was not in use and remained standing. Though the reinforced concrete block structure was afflicted by the shock and uplift, the relatively good performance was in stark contrast to that of the Olive View and Veterans Hospital complexes. Most of the buildings at the Los Angeles County owned, bed hospital complex had been built before the adoption of new construction techniques that had been put in place after the Long Beach earthquake.

The group of one-story structures feet west of the new facility, and some other buildings, were not damaged. The damaged buildings variously were wood-frame and masonry structures. The five-story, reinforced-concrete Medical Treatment and Care Building was one of three new additions to the complex all three of which sustained damagewas assembled with earthquake-resistant construction techniques, and was completed in December The hospital was staffed by 98 employees and had patients at the time of the earthquake; all three deaths that occurred at the Olive What features help a building withstand an earthquake complex were in this building.

Two were due to power failure of life-support systems and one, that of an employee who was struck by part of the collapsing building as he or she tried to exit the building, was a direct result of the destruction. The Medical Treatment and Care Building included a basement that was exposed above grade on the east and south sides, mixed above and below grade on the west side, and below grade on the north side of the building, the variation being due to the shallow slope at the site.

The complete structure, including the four external staircases, could be considered five separate buildings, because the stair towers were detached from the main building by about four inches. Earthquake bracing used in the building's second through fifth floors consisted of shear wallsbut a rarely used slip joint technique used with the concrete walls at the first floor kept them from being part of that system.

Damage to the building, including ceiling tiles, telephone equipment, and elevator doors, was excessive at the basement and the first floor, with little damage further up. The difference in rigidity at the second floor was proposed as a cause of the considerable damage to the lower levels.

Because the first floor almost collapsed, the building was leaning to the north by almost two feet, and three of the four concrete stair towers fell away from the main building.

On the grounds, there were cracks in the pavement and soil, but no surface faulting. In addition to the collapse of the stairways, the elevators were out of commission. Electrical power and communications failed at the hospital at the time of the earthquake, but very few people occupied the lower floors and the stairways at the early hour.

Casualties in these highly affected areas might have increased had the shock occurred later in the day. The duration of strong ground motion at that location was probably similar to the 12 seconds observed at the Pacoima Dam, and it is thought that another few seconds' shaking might have been enough to bring the building to collapse. The Veterans Administration Hospital entered into service as a tuberculosis hospital in and became a general hospital in the s.

Bythe facility comprised 45 individual buildings, all lying within 5 km 3. Twenty-six what do u do for swimmers ear that were built prior to had been what features help a building withstand an earthquake following the local building codes what can hydroelectricity be used for did not require seismic-resistant designs.

These buildings suffered the most damage, with four buildings totally collapsing, which resulted in a large loss of life at the facility. Most of the masonry and reinforced concrete buildings constructed after withstood the shaking and most did not collapse, but in a resolution came forth to abandon the site and the remaining structures were later demolished, the site becoming a city park.

Few strong motion seismometer installations were present outside of the western United States prior to the San Fernando earthquake but, upon a recommendation by the Earthquake and Wind Forces Committee, the Veterans Administration entered into an agreement with the Seismological Field Service then associated with NOAA to install the instruments at all VA sites in Uniform Building Code zones two and three. It had been established that these zones had a higher likelihood of experiencing strong ground acceleration, and the plan was made to furnish the selected VA hospitals with two instruments.

One unit would be installed within the structure and the second would be set up as a free-field unit located a short distance away from the facility. As ofa few of the highest risk 26 were completed in zone 3 alone sites that had been completed were in SeattleMemphisCharlestonand Boston. Both the Upper and Lower Van Norman dams were severely damaged as a result of the earthquake.

The lower dam was very close to breaching, and approximately 80, people were evacuated for four days while the water level in the reservoir was lowered.

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The lighter the building, especially toward the top, the more resistant it is against seismic effects. Earthquake protected structures have lightweight roofs and lighter floors, walls and partitions on upper levels. Restrictions in some areas limit the height a buildings can reach, due to deaths caused by falling debris in the past. There are several different kinds of earthquake-resistant bearings (see the Additional Background section for details), but in general, they have a few common features: They isolate the building's base from the movement of the ground, allowing the building and . May 09, The small city was badly hit in the earthquake and officials said a $bn copper refinery would help the economy. to withstand such an earthquake, with many collapsed classrooms.

Two millennia later, concrete has earned its rightful place as a trustworthy structural building material. In the s, new methods sped up steel production and it quickly gained fame as a strong and durable building material. Both are equally worthy structural materials.

Concrete costs more, but arguably offers better overall performance. To understand which material suits your project better, you must know how they compare in strength, durability, fire resistance, sustainability, and, of course, cost. Shear failure is caused by two unaligned forces acting on a building in different directions and typically occurs during an earthquake or due to strong winds.

Concrete has excellent compressive strength, but is very brittle, and fractures easily under tension. To counter this weakness, reinforcing bars made of a tension-resisting material are embedded into it. These bars are typically steel, although composite options are also available. Vertical bars running along the length of the structural member are tied with shorter, perpendicular bars called stirrups, these stirrups provide the shear strength.

Sound structural design is key to achieving sufficient compressive, tensile, and shear strength in a steel structure. Durability is the degree to which a material can weather its surroundings. Properly adapted, reinforced concrete endures freeze-thaw cycles, chemicals, seawater, moisture, solar radiation, and abrasion.

But despite its high durability, reinforced concrete hides a potential flaw - the same corrosion-prone steel reinforcement that makes it stronger. Rusting rebar loses its bond with the surrounding concrete and creates iron oxide, which expands, resulting in tensile stressesand eventual deterioration. Epoxy-coated, stainless steel, or composite rebar work well for this purpose. Structural steel is as susceptible to corrosion as rebar and also requires protection.

Paint, powder coating, sacrificial layers, and corrosion inhibiting chemicals are all methods that can eliminate or limit corrosive damage to structural steel. That said, both the concrete and the steel reinforcement can lose their strength once exposed to high temperatures for a long time. Studies show that lightweight concrete has the best resistance to fires thanks to its insulating properties and a poorer rate of heat transfer. Structural steel is less resistant to fire than reinforced concrete.

A variety of methods can slow the rate of temperature rise in the structural steel elements of a building. These may include fire-resistive coatings, barriers, cooling systems, concrete encasement, and active measures, such as sprinklers.

Both concrete and steel offer environmental benefits when used in construction. It only makes sense, given the abundance of scrap metal and the easy recycling process. Besides reducing the demand for newly mined resources, steel recycling consumes only a third of the energy to that consumed during steel production. Concrete also boasts several sustainable features. Most of it originates in relative proximity to the construction site, curtailing the amount of energy needed for shipping.

After demolition, it can be recycled to produce gravel, aggregate or paving materials for roadway construction, erosion control, landscaping, oceanic reef restoration, and other tasks.

Uncontaminated concrete may be turned into aggregate for new mixes. Recycling concrete has many environmental benefits. It keeps rubble out of landfills, cuts down construction waste, and replaces gravel and aggregates that would otherwise be mined and shipped.

Reinforced concrete tends to be a costlier alternative to structural steel. The labor and materials involved in placing formwork and rebar, pouring concrete, and ensuring that it cures properly, can comprise a significant chunk of the total costs.

That said, concrete prices are relatively stable. Since , prices for various concrete products have grown steadily with the rate of inflation, and this is an important factor to keep in mind when pricing projects planned for the distant future.

Typically, insurance companies give concrete structures higher safety rankings and lower premiums on their policies. Steel is cheaper than concrete and faster to erect, but comes with a longer lead time. Due to its lower fire resistance, insurance premiums for steel structures tend to be higher. Steel prices are notoriously volatile, and the last two decades paint a chaotic picture.

After peaking in the early months of , they entered a downward spiral with the Great Recession. Ten more years of ups and downs, and steel spiked once more in Such price fluctuations present a major budgeting challenge and this is likely to continue given the current global economic instability.

Call us for a FREE consultation and quote. For Homeowner. The warehouse in California has a steel structure. So, which of these materials is more suitable for your project? Durability Durability is the degree to which a material can weather its surroundings. Sustainability Both concrete and steel offer environmental benefits when used in construction.

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2 thoughts on “What features help a building withstand an earthquake

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