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90-422: From 1998 to 2003, the building underwent a massive renovation, expansion, and seismic retrofit , in which a platform was built underneath the building, and a suspension system capable of up to 1 meter lateral travel was installed. To keep the expansion distinct from the historic building, shot peened aluminium (rather than stone) and a more modern design were used in the new construction. The Lawson Adit -

180-548: A bowl of gelatin dessert . To avoid overstressing the tube due to differential movements at each end, a sliding slip joint was included at the San Francisco terminus under the landmark Ferry Building . The engineers of the construction consortium PBTB (Parsons Brinckerhoff-Tudor-Bechtel) used the best estimates of ground motion available at the time, now known to be insufficient given modern computational analysis methods and geotechnical knowledge. Unexpected settlement of

270-469: A building as a library, for instance, may without inconsistency rejoice in all the sumptuous glories of Roman architecture or the Renaissance; the tradition of the world leads on naturally enough in this direction. But ... such delicate and highly organized motives find little place in a Mining Building, which demands a treatment, while no less beautiful, much more primitive, less elaborately developed in

360-504: A building move from its foundation or fall due to cripple wall collapse, the ductile iron pipes transporting the gas within the structure may be broken, typically at the location of threaded joints. The gas may then still be provided to the pressure regulator from higher pressure lines and so continue to flow in substantial quantities; it may then be ignited by a nearby source such as a lit pilot light or arcing electrical connection. There are two primary methods of automatically restraining

450-627: A frame-building, as often observed in recent earthquakes For reinforced concrete beam-column joints – various retrofit solutions have been proposed and tested in the past 20 years. Philosophically, the various seismic retrofit strategies discussed above can be implemented for reinforced concrete joints. Concrete or steel jacketing have been a popular retrofit technique until the advent of composite materials such as Carbon fiber-reinforced polymer (FRP). Composite materials such as carbon FRP and aramic FRP have been extensively tested for use in seismic retrofit with some success. One novel technique includes

540-464: A high probability of moving en masse , carrying entire sections of suburban development to new locations. While the most modern of house structures (well tied to monolithic concrete foundation slabs reinforced with post tensioning cables) may survive such movement largely intact, the building will no longer be in its proper location. Natural gas and propane supply pipes to structures often prove especially dangerous during and after earthquakes. Should

630-550: A horizontal mining tunnel - is directly to the east of the building. Construction of the Hearst Memorial Mining Building began in 1902, and the building was completed in 1907, with a dedication ceremony held on August 23 of that year. The $ 1.065 million construction cost was a gift of Phoebe Apperson Hearst , dedicated to the memory of her late husband, Senator George Hearst , who had made much of his fortune in mining. When construction began in 1903,

720-851: A large, deep landslide. The likelihood of landslide or soil failure may also depend upon seasonal factors, as the soil may be more stable at the beginning of a wet season than at the beginning of the dry season. Such a "two season" Mediterranean climate is seen throughout California . In some cases, the best that can be done is to reduce the entrance of water runoff from higher, stable elevations by capturing and bypassing through channels or pipes, and to drain water infiltrated directly and from subsurface springs by inserting horizontal perforated tubes. There are numerous locations in California where extensive developments have been built atop archaic landslides, which have not moved in historic times but which (if both water-saturated and shaken by an earthquake) have

810-752: A lawyer and politician from Bordeaux and Anne-Dominique Gourg (1764-1851), daughter and granddaughter of cognac merchants. He entered the Collège Sainte-Barbe as a student in 1809. He was then admitted into the second class and the Lebas-Vaudoyer workshop in the École Royale des Beaux Arts in 1819. In 1820, he was promoted to the first class. Competing for the Grand Prix, Labrouste was awarded second place (the Palais de Justice scored first) by Guillaume-Abel Blouet in 1821. In 1823, he won

900-400: A method frequently used to attach outdoor decks to existing buildings. This is seen in conditions of damp soil, especially in tropical conditions, as it leaves a dry ventilated space under the house, and in far northern conditions of permafrost (frozen mud) as it keeps the building's warmth from destabilizing the ground beneath. During an earthquake, the pylons may tip, spilling the building to

990-420: A perimeter or slab foundation are relatively safe in an earthquake, but in many structures built before 1950 the sill plate that sits between the concrete foundation and the floor diaphragm (perimeter foundation) or studwall (slab foundation) may not be sufficiently bolted in. Additionally, older attachments (without substantial corrosion-proofing) may have corroded to a point of weakness. A sideways shock can slide

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1080-442: A plain honest man and good miner. The stature and mould of his life bespoke the pioneers who gave their strength to riskful search in the hard places of the earth. He had warm heart toward his fellow men and his hand was ready to kindly deed. Taking his wealth from the hills he filched from no man's store and lessened no man's opportunity. The rooms to the south and west of the vestibule were originally administrative offices, including

1170-680: A result, the addition may have a different resonant period than the original structure, and they may easily detach from one another. The relative motion will then cause the two parts to collide, causing severe structural damage. Seismic modification will either tie the two building components rigidly together so that they behave as a single mass or it will employ dampers to expend the energy from relative motion, with appropriate allowance for this motion, such as increased spacing and sliding bridges between sections. Historic buildings, made of unreinforced masonry, may have culturally important interior detailing or murals that should not be disturbed. In this case,

1260-419: A shield through the soft bay mud, the tube was constructed on land in sections. Each section consisted of two inner train tunnels of circular cross section, a central access tunnel of rectangular cross section, and an outer oval shell encompassing the three inner tubes. The intervening space was filled with concrete. At the bottom of the bay a trench was excavated and a flat bed of crushed stone prepared to receive

1350-407: A slope, a slope failure or landslide , or in a flat area due to liquefaction of water-saturated sand and/or mud. Generally, deep pilings must be driven into stable soil (typically hard mud or sand) or to underlying bedrock or the slope must be stabilized. For buildings built atop previous landslides the practicality of retrofit may be limited by economic factors, as it is not practical to stabilize

1440-418: Is a kind of seismic vibration control , can be applied both to a newly designed building and to seismic upgrading of existing structures. Normally, excavations are made around the building and the building is separated from the foundations. Steel or reinforced concrete beams replace the connections to the foundations, while under these, the isolating pads, or base isolators, replace the material removed. While

1530-408: Is a large container of low viscosity fluid (usually water) that may be placed at locations in a structure where lateral swaying motions are significant, such as the roof, and tuned to counter the local resonant dynamic motion. During a seismic (or wind) event the fluid in the tank will slosh back and forth with the fluid motion usually directed and controlled by internal baffles – partitions that prevent

1620-407: Is done to divert snow avalanches ) or the slope above the tunnel may be stabilized in some way. Where only small- to medium-sized rocks and boulders are expected to fall, the entire slope may be covered with wire mesh, pinned down to the slope with metal rods. This is also a common modification to highway cuts where appropriate conditions exist. The safety of underwater tubes is highly dependent upon

1710-443: Is known as soft story collapse . In many buildings the ground level is designed for different uses than the upper levels. Low rise residential structures may be built over a parking garage which have large doors on one side. Hotels may have a tall ground floor to allow for a grand entrance or ballrooms. Office buildings may have retail stores on the ground floor with continuous display windows . Traditional seismic design assumes that

1800-510: Is of the classical tradition. The roof tiles are reminiscent of Spanish roofing tiles used in late (post-1790) California mission architecture. As the building's centerpiece, the center vestibule was made notable from the exterior by being made the highest point of the building's facade. Howard unified the exterior facade not by the classical elements of symmetry and hierarchy, but rather filled in voids with ornamental details. Six granite corbel sculptures created by Robert Ingersoll Aitken support

1890-486: Is the modification of existing structures to make them more resistant to seismic activity , ground motion , or soil failure due to earthquakes . With better understanding of seismic demand on structures and with recent experiences with large earthquakes near urban centers, the need of seismic retrofitting is well acknowledged. Prior to the introduction of modern seismic codes in the late 1960s for developed countries (US, Japan etc.) and late 1970s for many other parts of

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1980-610: Is to include at some upper story a large mass, constrained, but free to move within a limited range, and moving on some sort of bearing system such as an air cushion or hydraulic film. Hydraulic pistons , powered by electric pumps and accumulators, are actively driven to counter the wind forces and natural resonances. These may also, if properly designed, be effective in controlling excessive motion – with or without applied power – in an earthquake. In general, though, modern steel frame high rise buildings are not as subject to dangerous motion as are medium rise (eight to ten story ) buildings, as

2070-420: Is to surround the column with a jacket of steel plates formed and welded into a single cylinder. The space between the jacket and the column is then filled with concrete, a process called grouting. Where soil or structure conditions require such additional modification, additional pilings may be driven near the column base and concrete pads linking the pilings to the pylon are fabricated at or below ground level. In

2160-415: The 1994 Northridge earthquake brought to light the brittleness of welded steel frames, for example. The retrofit techniques outlined here are also applicable for other natural hazards such as tropical cyclones , tornadoes , and severe winds from thunderstorms . Whilst current practice of seismic retrofitting is predominantly concerned with structural improvements to reduce the seismic hazard of using

2250-403: The 1994 Northridge earthquake . Typically, where this type of problem is found, the weak story is reinforced to make it stronger than the floors above by adding shear walls or moment frames. Moment frames consisting of inverted U bents are useful in preserving lower story garage access, while a lower cost solution may be to use shear walls or trusses in several locations, which partially reduce

2340-506: The base isolation tends to restrict transmission of the ground motion to the building, it also keeps the building positioned properly over the foundation. Careful attention to detail is required where the building interfaces with the ground, especially at entrances, stairways and ramps, to ensure sufficient relative motion of those structural elements. Supplementary dampers absorb the energy of motion and convert it to heat, thus damping resonant effects in structures that are rigidly attached to

2430-413: The 1994 Northridge earthquake had a number of features that rendered it inherently susceptible to brittle fracture. Floors in wooden buildings are usually constructed upon relatively deep spans of wood, called joists , covered with a diagonal wood planking or plywood to form a subfloor upon which the finish floor surface is laid. In many structures these are all aligned in the same direction. To prevent

2520-492: The BART tube include vibratory consolidation of the tube's overfill to avoid potential liquefying of the overfill, which has now been completed. (Should the overfill fail there is a danger of portions of the tube rising from the bottom, an event which could potentially cause failure of the section connections.) Bridges have several failure modes. Many short bridge spans are statically anchored at one end and attached to rockers at

2610-522: The College of Mines, with its 247 students (or 11% of the total student population at the university) was the largest of its kind in the world. The college did not have a dedicated building, and due to the size of the college, the Hearst Memorial Mining Building was chosen as the first building under the Hearst Plan to be constructed. University architect John Galen Howard designed the building with

2700-527: The Hearst campus plan. In order to help them realize this vision, Hearst funded a trip for Howard and Christy to visit mining schools throughout the United States and Europe so that they could study standardized architectural forms for mining schools, as libraries and hospitals had realized in their own architectural evolution. Howard and Christy did not find many examples of mining colleges—the majority of

2790-810: The Medici Villa in Rome. The directors of the Académie stated in correspondence in French about the laureates that, in their studies of antiquity, they "must research the laws of proportion and reduce them to formulas to be used by masters and students in Paris." His work was the subject of "Henri Labrouste: Structure Brought to Light," the first solo exhibition in the U.S. of his work, at The Museum of Modern Art in New York City. His buildings include: For

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2880-474: The Northridge earthquake, a number of steel moment -frame buildings were found to have experienced brittle fractures of beam to column connections. Discovery of these unanticipated brittle fractures of framing connections was alarming to engineers and the building industry. Starting in the 1960s, engineers began to regard welded steel moment-frame buildings as being among the most ductile systems contained in

2970-536: The Office of the Dean. Lecture halls and the museum curator's office were on the south and east sides, respectively. In the central court to the north of the vestibule was the mining laboratory, and on the east and west ends of the laboratory were the metallurgic and research labs, a library, offices and lecture space. The 3-story-tall tower at the north end of the building was used for the crushing of dry ore. Adjacent east of

3060-476: The SAC Steel project. Under Phase II, SAC continued its extensive problem-focused study of the performance of moment resisting steel frames and connections of various configurations, with the ultimate goal of developing seismic design criteria for steel construction. As a result of these studies it is now known that the typical moment-resisting connection detail employed in steel moment frame construction prior to

3150-580: The United States in 1881, earning notability for his work in the Boston Public Library vaults in the 1890s. Howard and the Guastavino Company kept a professional correspondence prior to the construction of the mining building, and Howard hired Guastavino's workers to install the tilework. A plaque dedicated to George Hearst was placed on the north wall of the entryway, reading: This building stands as memorial to George Hearst,

3240-540: The alluvium can be amplified, just as are water waves against a sloping beach . In these special conditions, vertical accelerations up to twice the force of gravity have been measured. If a building is not secured to a well-embedded foundation it is possible for the building to be thrust from (or with) its foundations into the air, usually with severe damage upon landing. Even if it is well-founded, higher portions such as upper stories or roof structures or attached structures such as canopies and porches may become detached from

3330-458: The assistance of the Dean of the College of Mines, Professor Samuel B. Christy and Berkeley -educated architect Julia Morgan . The architects set out to create a building that harmonized classical elements with architectural innovation, building off prior examples of European and American mining building architecture, and staying true to the Beaux-Arts style that defined Howard's vision for

3420-411: The beams from tipping over onto their side, blocking is used at each end, and for additional stiffness, blocking or diagonal wood or metal bracing may be placed between beams at one or more points in their spans. At the outer edge it is typical to use a single depth of blocking and a perimeter beam overall. If the blocking or nailing is inadequate, each beam can be laid flat by the shear forces applied to

3510-422: The building code. Many engineers believed that steel moment-frame buildings were essentially invulnerable to earthquake induced damage and thought that should damage occur, it would be limited to ductile yielding of members and connections. Observation of damage sustained by buildings in the 1994 Northridge earthquake indicated that contrary to the intended behavior, in many cases, brittle fractures initiated within

3600-442: The building entirely off of the foundations or slab. Often such buildings, especially if constructed on a moderate slope, are erected on a platform connected to a perimeter foundation through low stud-walls called "cripple wall" or pin-up . This low wall structure itself may fail in shear or in its connections to itself at the corners, leading to the building moving diagonally and collapsing the low walls. The likelihood of failure of

3690-426: The building is constructed upon a single and relatively thick monolithic slab, kept in one piece by high tensile rods that are stressed after the slab has set. This poststressing places the concrete under compression – a condition under which it is extremely strong in bending and so will not crack under adverse soil conditions. Some older low-cost structures are elevated on tapered concrete pylons set into shallow pits,

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3780-440: The building. In this position they lack most of their original strength and the structure may further collapse. As part of a retrofit the blocking may be doubled, especially at the outer edges of the building. It may be appropriate to add additional nails between the sill plate of the perimeter wall erected upon the floor diaphragm, although this will require exposing the sill plate by removing interior plaster or exterior siding. As

3870-432: The buildings they visited were originally built for other purposes. Howard feared that the scant number examples to study would make his design prone to the mistakes of an architectural form early in its evolution. This problem is what inspired Howard to create an "elastic" design—the building's exterior shell would be built separate from the interior, so that the interior could be modified in the future without having to scrap

3960-471: The capacity of structural elements such as beam, column and beam-column joints. External pre-stressing has been used for structural upgrade for gravity/live loading since the 1970s. Base isolation is a collection of structural elements of a building that should substantially decouple the building's structure from the shaking ground thus protecting the building's integrity and enhancing its seismic performance . This earthquake engineering technology, which

4050-550: The connections at very low levels of plastic demand. In September 1994, The SAC joint Venture, AISC, AISI, and NIST jointly convened an international workshop in Los Angeles to coordinate the efforts of various participants and to lay the foundation for systematic investigation and resolution of the problem. In September 1995 the SAC Joint Venture entered into a contractual agreement with FEMA to conduct Phase II of

4140-526: The departmental prize and worked as a lieutenant-inspector ( sous-inspecteur ) for the director Étienne-Hippolyte Godde during the construction of the Saint-Pierre-du-Gros-Caillou parish in Paris. In 1824 Labrouste won the competition with a design of a Court of Appeals (Cour de cassation). In November, he left Paris for Italy, visiting Turin, Milan, Lodi, Piacenza, Parma, Modena, Bologna, Florence and Arezzo. In July 1835 in Paris he

4230-471: The example shown not all columns needed to be modified to gain sufficient seismic resistance for the conditions expected. (This location is about a mile from the Hayward Fault Zone .) Concrete walls are often used at the transition between elevated road fill and overpass structures. The wall is used both to retain the soil and so enable the use of a shorter span and also to transfer the weight of

4320-457: The flow of gas after an earthquake, installed on the low pressure side of the regulator, and usually downstream of the gas meter. It appears that the most secure configuration would be to use one of each of these devices in series. Unless the tunnel penetrates a fault likely to slip, the greatest danger to tunnels is a landslide blocking an entrance. Additional protection around the entrance may be applied to divert any falling material (similar as

4410-407: The frame. Examples of retrofit techniques for masonry infills include steel reinforced plasters, engineered cementitious composites , thin layers fibre-reinforced polymers (FRP), and most recently also textile-reinforced mortars (TRM). Where moist or poorly consolidated alluvial soil interfaces in a "beach like" structure against underlying firm material, seismic waves traveling through

4500-507: The function of the building. In an interview with the University of California Magazine in 1902, 5 years before the building's dedication ceremony, Howard reflects: The aim has been to give expression to the character of a College of Mining Engineering as distinguished from one of Art, Letters, or of Natural Science. The expression of belles-lettres in architecture demands a more purely classic character than that of scientific studies. Such

4590-804: The ground. In addition to adding energy dissipation capacity to the structure, supplementary damping can reduce the displacement and acceleration demand within the structures. In some cases, the threat of damage does not come from the initial shock itself, but rather from the periodic resonant motion of the structure that repeated ground motion induces. In the practical sense, supplementary dampers act similarly to Shock absorbers used in automotive suspensions . Tuned mass dampers (TMD) employ movable weights on some sort of springs. These are typically employed to reduce wind sway in very tall, light buildings. Similar designs may be employed to impart earthquake resistance in eight to ten story buildings that are prone to destructive earthquake induced resonances. A slosh tank

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4680-520: The ground. This can be overcome by using deep-bored holes to contain cast-in-place reinforced pylons, which are then secured to the floor panel at the corners of the building. Another technique is to add sufficient diagonal bracing or sections of concrete shear wall between pylons. Reinforced concrete columns typically contain large diameter vertical rebar (reinforcing bars) arranged in a ring, surrounded by lighter-gauge hoops of rebar. Upon analysis of failures due to earthquakes, it has been realized that

4770-442: The infill panels due to in and out-of-plane mechanisms, but also due to their combination, can lead to a sudden drop in capacity and hence cause global brittle failure of the structure. Even at lower intensity earthquakes, damage to infilled frames can lead to high economic losses and loss of life. To prevent masonry infill damage and failure, typical retrofit strategies aim to strengthen the infills and provide adequate connection to

4860-499: The internal structure are composed of steel beams, and continue through two floors of balconies lined with blue-green cast-iron railings housed upon steel lattice trusses. Construction details such as its bricks are intentionally exposed to communicate a brusk aesthetic. The Guastavino tiles were a proprietary feature to the domed structural system. They were designed by the Valencian architect Rafael Guastavino , who had immigrated to

4950-464: The introduction of new seismic provisions and the availability of advanced materials (e.g. fiber-reinforced polymers (FRP) , fiber reinforced concrete and high strength steel). Recently more holistic approaches to building retrofitting are being explored, including combined seismic and energy retrofitting. Such combined strategies aim to exploit cost savings by applying energy retrofitting and seismic strengthening interventions at once, hence improving

5040-405: The lower stories of a building are stronger than the upper stories; where this is not the case—if the lower story is less strong than the upper structure—the structure will not respond to earthquakes in the expected fashion. Using modern design methods, it is possible to take a weak lower story into account. Several failures of this type in one large apartment complex caused most of the fatalities in

5130-455: The lower stories that only limited shear reinforcement was required to make it earthquake resistant for this location near the Hayward fault . In other circumstances, far greater reinforcement is required. In the structure shown at right – a parking garage over shops – the placement, detailing, and painting of the reinforcement becomes itself an architectural embellishment. This collapse mode

5220-501: The lower stories. Common retrofit measures for unreinforced masonry buildings in the Western United States include the addition of steel frames, the addition of reinforced concrete walls, and in some cases, the addition of base isolation. Frequently, building additions will not be strongly connected to the existing structure, but simply placed adjacent to it, with only minor continuity in flooring, siding, and roofing. As

5310-475: The matter of detail, less influenced by the extreme classic tradition either as a canon of proportion or as an architectonic schema. The profession of mining has to do with the very body and bone of the earth; its process is a ruthless assault upon the bowels of the world, a contest with the crudest and most rudimentary forces. There is about it something essentially elementary, something primordial; and its expression in architecture must, to be true, have something of

5400-571: The motion relative to the anchorage. Suspension bridges may respond to earthquakes with a side-to-side motion exceeding that which was designed for wind gust response. Such motion can cause fragmentation of the road surface, damage to bearings, and plastic deformation or breakage of components. Devices such as hydraulic dampers or clamped sliding connections and additional diagonal reinforcement may be added. Henri Labrouste Pierre-François-Henri Labrouste ( French: [pjɛʁ fʁɑ̃swa ɑ̃ʁi labrust] ) (11 May 1801 – 24 June 1875)

5490-612: The new elements, a form is erected, and an additional layer of concrete is poured. This modification may be combined with additional footings in excavated trenches and additional support ledgers and tie-backs to retain the span on the bounding walls. In masonry structures, brick building structures have been reinforced with coatings of glass fiber and appropriate resin (epoxy or polyester). In lower floors these may be applied over entire exposed surfaces, while in upper floors this may be confined to narrow areas around window and door openings. This application provides tensile strength that stiffens

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5580-643: The other. This rocker gives vertical and transverse support while allowing the bridge span to expand and contract with temperature changes. The change in the length of the span is accommodated over a gap in the roadway by comb-like expansion joints . During severe ground motion, the rockers may jump from their tracks or be moved beyond their design limits, causing the bridge to unship from its resting point and then either become misaligned or fail completely. Motion can be constrained by adding ductile or high-strength steel restraints that are friction-clamped to beams and designed to slide under extreme stress while still limiting

5670-572: The past decade. Under the PRESS (Precast Seismic Structural Systems), a large-scale U.S./Japan joint research program, unbonded post-tensioning high strength steel tendons have been used to achieve a moment-resisting system that has self-centering capacity. An extension of the same idea for seismic retrofitting has been experimentally tested for seismic retrofit of California bridges under a Caltrans research project and for seismic retrofit of non-ductile reinforced concrete frames. Pre-stressing can increase

5760-646: The pin-up can be reduced by ensuring that the corners are well reinforced in shear and that the shear panels are well connected to each other through the corner posts. This requires structural grade sheet plywood, often treated for rot resistance. This grade of plywood is made without interior unfilled knots and with more, thinner layers than common plywood. New buildings designed to resist earthquakes will typically use OSB ( oriented strand board ), sometimes with metal joins between panels, and with well attached stucco covering to enhance its performance. In many modern tract homes, especially those built upon expansive (clay) soil

5850-652: The primary structure. Good practices in modern, earthquake-resistant structures dictate that there be good vertical connections throughout every component of the building, from undisturbed or engineered earth to foundation to sill plate to vertical studs to plate cap through each floor and continuing to the roof structure. Above the foundation and sill plate the connections are typically made using steel strap or sheet stampings, nailed to wood members using special hardened high-shear strength nails, and heavy angle stampings secured with through bolts, using large washers to prevent pull-through. Where inadequate bolts are provided between

5940-436: The resonant period of a tall and massive building is longer than the approximately one second shocks applied by an earthquake. The most common form of seismic retrofit to lower buildings is adding strength to the existing structure to resist seismic forces. The strengthening may be limited to connections between existing building elements or it may involve adding primary resisting elements such as walls or frames, particularly in

6030-540: The rude, the Cyclopean. The emotion roused must be a sense of power, rather than that of grace ... To produce a design for a Mining Building which shall in all sincerity express its purpose and at the same time harmonize with future buildings quite as sincere in the expression of their purposes--purposes in almost every case of greater amenity--this has been the aim of the architect in approaching his task in its artistic phase. Seismic retrofit Seismic retrofitting

6120-519: The seismic and thermal performance of buildings. In the past, seismic retrofit was primarily applied to achieve public safety, with engineering solutions limited by economic and political considerations. However, with the development of Performance-based earthquake engineering (PBEE), several levels of performance objectives are gradually recognised: Common seismic retrofitting techniques fall into several categories: The use of external post-tensioning for new structural systems have been developed in

6210-456: The shell or compromise the building's strength. Vents and chimneys were also built independent of the shell, as these architectural features were expected to have shorter lifespans than the exterior structure. California Hall , another Howard-designed building on the Berkeley campus was also constructed with an "elastic" interior form. Howard, reflecting upon their work after the construction

6300-445: The sill plate may be quite old and dry and substantial nails must be used, it may be necessary to pre-drill a hole for the nail in the old wood to avoid splitting. When the wall is opened for this purpose it may also be appropriate to tie vertical wall elements into the foundation using specialty connectors and bolts glued with epoxy cement into holes drilled in the foundation. Single or two-story wood-frame domestic structures built on

6390-465: The sill plates and a foundation in existing construction (or are not trusted due to possible corrosion), special clamp plates may be added, each of which is secured to the foundation using expansion bolts inserted into holes drilled in an exposed face of concrete. Other members must then be secured to the sill plates with additional fittings. One of the most difficult retrofits is that required to prevent damage due to soil failure. Soil failure can occur on

6480-521: The soil conditions through which the tunnel was constructed, the materials and reinforcements used, and the maximum predicted earthquake expected, and other factors, some of which may remain unknown under current knowledge. A tube of particular structural, seismic, economic, and political interest is the BART (Bay Area Rapid Transit) transbay tube . This tube was constructed at the bottom of San Francisco Bay through an innovative process. Rather than pushing

6570-449: The solution may be to add a number of steel, reinforced concrete, or poststressed concrete columns to the exterior. Careful attention must be paid to the connections with other members such as footings, top plates, and roof trusses. Shown here is an exterior shear reinforcement of a conventional reinforced concrete dormitory building. In this case, there was sufficient vertical strength in the building columns and sufficient shear strength in

6660-404: The span directly downward to footings in undisturbed soil. If these walls are inadequate they may crumble under the stress of an earthquake's induced ground motion. One form of retrofit is to drill numerous holes into the surface of the wall, and secure short L -shaped sections of rebar to the surface of each hole with epoxy adhesive . Additional vertical and horizontal rebar is then secured to

6750-422: The structures, it is similarly essential to reduce the hazards and losses from non-structural elements. It is also important to keep in mind that there is no such thing as an earthquake-proof structure, although seismic performance can be greatly enhanced through proper initial design or subsequent modifications. Seismic retrofit (or rehabilitation) strategies have been developed in the past few decades following

6840-701: The surrounding air. One Rincon Hill in San Francisco is a skyscraper with a rooftop slosh tank which was designed primarily to reduce the magnitude of lateral swaying motion from wind. A slosh tank is a passive tuned mass damper . In order to be effective the mass of the liquid is usually on the order of 1% to 5% of the mass it is counteracting, and often this requires a significant volume of liquid. In some cases these systems are designed to double as emergency water cisterns for fire suppression. Very tall buildings (" skyscrapers "), when built using modern lightweight materials, might sway uncomfortably (but not dangerously) in certain wind conditions. A solution to this problem

6930-408: The tank itself becoming resonant with the structure, see Slosh dynamics . The net dynamic response of the overall structure is reduced due to both the counteracting movement of mass, as well as energy dissipation or vibration damping which occurs when the fluid's kinetic energy is converted to heat by the baffles. Generally the temperature rise in the system will be minimal and is passively cooled by

7020-467: The tower was the copper and lead smelting laboratory, and adjacent west a gold and silver mill. Howard gave the building a brusque, industrial aesthetic as a complement to the softer aesthetic of the other buildings in the Hearst Plan. Howard referred to the Mining Building as " the kind, bluff brother amid a bevy of lovely sisters ". These architectural features were also intended to communicate

7110-454: The tube has reduced the amount of slip that can be accommodated without failure. These factors have resulted in the slip joint being designed too short to ensure survival of the tube under possible (perhaps even likely) large earthquakes in the region. To correct this deficiency the slip joint must be extended to allow for additional movement, a modification expected to be both expensive and technically and logistically difficult. Other retrofits to

7200-421: The tube sections. The sections were then floated into place and sunk, then joined with bolted connections to previously placed sections. An overfill was then placed atop the tube to hold it down. Once completed from San Francisco to Oakland, the tracks and electrical components were installed. The predicted response of the tube during a major earthquake was likened to be as that of a string of (cooked) spaghetti in

7290-776: The use of selective weakening of the beam and added external post-tensioning to the joint in order to achieve flexural hinging in the beam, which is more desirable in terms of seismic design. Widespread weld failures at beam-column joints of low-to-medium rise steel buildings during the Northridge 1994 earthquake for example, have shown the structural defiencies of these 'modern-designed' post-1970s welded moment-resisting connections. A subsequent SAC research project [4] has documented, tested and proposed several retrofit solutions for these welded steel moment-resisting connections. Various retrofit solutions have been developed for these welded joints – such as a) weld strengthening and b) addition of steel haunch or 'dog-bone' shape flange. Following

7380-534: The usefulness for automobile parking but still allow the space to be used for other storage. Beam-column joint connections are a common structural weakness in dealing with seismic retrofitting. Prior to the introduction of modern seismic codes in early 1970s, beam-column joints were typically non-engineered or designed. Laboratory testings have confirmed the seismic vulnerability of these poorly detailed and under-designed connections. Failure of beam-column joint connections can typically lead to catastrophic collapse of

7470-502: The wall against bending away from the side with the application. The efficient protection of an entire building requires extensive analysis and engineering to determine the appropriate locations to be treated. In reinforced concrete buildings, masonry infill walls are considered non-structural elements, but damage to infills can lead to large repair costs and change the behaviour of a structure, even leading to aforementioned soft-storey or beam-column joint shear failures. Local failure of

7560-413: The weakness was not in the vertical bars, but rather in inadequate strength and quantity of hoops. Once the integrity of the hoops is breached, the vertical rebar can flex outward, stressing the central column of concrete. The concrete then simply crumbles into small pieces, now unconstrained by the surrounding rebar. In new construction a greater amount of hoop-like structures are used. One simple retrofit

7650-415: The wooden roof brackets. According to Howard, the two male sculptures on the west signified " primal elements ", and the two on the east " eternal forces ", representative of the character of mining. The two central female sculptures provided a balancing presence, representing " the ideal art, the final flower of life--fresh, mysterious, pure--emerging from the void of chaos ". The central entrance vestibule

7740-606: The world (Turkey, China etc.), many structures were designed without adequate detailing and reinforcement for seismic protection. In view of the imminent problem, various research work has been carried out. State-of-the-art technical guidelines for seismic assessment, retrofit and rehabilitation have been published around the world – such as the ASCE-SEI 41 and the New Zealand Society for Earthquake Engineering (NZSEE)'s guidelines. These codes must be regularly updated;

7830-451: Was a French architect from the famous École des Beaux-Arts school of architecture. After a six-year stay in Rome, Labrouste established an architectural training workshop, which soon became known for rationalism. He became noted for his use of iron-frame construction and was one of the first to realize the importance of its use. Born in Paris, Labrouste was one of five children of François-Marie-Alexandre Labrouste  [ fr ] ,

7920-409: Was complete, said: We have sought to secure beauty not by easy masquerade and putting on of architectural stuff, but by organic composition, working from within out, and letting the heart of the thing speak ... If the expression be true, no matter how strange it may seem at first, in the end it must be seen to be inevitable. The roof of the building is tiled, brackets made of timber, and ornamentation

8010-537: Was dedicated to Senator Hearst, and was also to serve as a space for the mining museum. It was designed to recall Henri Labrouste 's Reading Room in the Bibliothèque Nationale de France (1858–68). The golden oak doors that open into it from the building's exterior were intended to create a dramatic entrance into an equally dramatic, high-ceilinged space where domes 50 feet in the air are covered in buff-toned Guastavino tiles . The columns that support

8100-476: Was present at the scene when Giuseppe Marco Fieschi attempted the assassination of King Louis-Philippe using a home-made, multi-barrel gun fired from an upstairs window. Although the King only received a minor injury, 18 people were killed, including Henri's father, Alexandre Labrouste. Receiving a pension or stipend from the French government for five years, he and the other Académie française laureates stayed in

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