Žemės drebėjimo inžinerija is an tarpdisciplininis branch of engineering that designs and analyzes structures, such as buildings and bridges, with žemės drebėjimų in mind. Its overall goal is to make such structures more resistant to earthquakes. An earthquake (or seismic) engineer aims to construct structures that will not be damaged in minor shaking and will avoid serious damage or collapse in a major earthquake. Earthquake engineering is the scientific field concerned with protecting society, the natural environment, and the man-made environment from earthquakes by limiting the seisminė rizika to socialiniu-ekonominiu požiūriu acceptable levels.1 Traditionally, it has been narrowly defined as the study of the behavior of structures and geo-structures subject to seisminė apkrova; it is considered as a subset of struktūrinė inžinerija, geotechninė inžinerija, Mechaninė inžinerija, chemijos inžinerija, taikomoji fizika, etc. However, the tremendous costs experienced in recent earthquakes have led to an expansion of its scope to encompass disciplines from the wider field of Civilinė inžinerija, Mechaninė inžinerija, branduolinė inžinerija, and from the visuomeniniai mokslai, especially sociologija, politiniai mokslai, ekonomika, and finansų.2
Pagrindiniai žemės drebėjimo inžinerijos tikslai yra šie:
Foresee the potential consequences of strong žemės drebėjimų on Miesto zonos and civil infrastructure.
Design, construct and maintain structures to atlikti at earthquake exposure up to the expectations and in compliance with statybos kodeksus.3
A tinkamai suprojektuota konstrukcija does not necessarily have to be extremely strong or expensive. It has to be properly designed to withstand the seismic effects while sustaining an acceptable level of damage.
Seisminė apkrova
Seisminė apkrova means application of an earthquake-generated excitation on a structure (or geo-structure). It happens at contact surfaces of a structure either with the ground,5 with adjacent structures,6 or with gravitacijos bangos from cunamis. The loading that is expected at a given location on the Earth's surface is estimated by engineering seismologija. It is related to the seisminis pavojus of the location.
Seisminis veikimas
Žemės drebėjimas or seisminis veikimas defines a structure's ability to sustain its main functions, such as its saugumo and tinkamumas naudoti, adresu and po to a particular earthquake exposure. A structure is normally considered saugus if it does not endanger the lives and gerovei- of those in or around it by partially or completely collapsing. A structure may be considered tinkamas naudoti if it is able to fulfill its operational functions for which it was designed.
Pagrindinės žemės drebėjimo inžinerijos koncepcijos, įgyvendintos pagrindiniuose statybos kodeksuose, daro prielaidą, kad pastatas turi išgyventi retą, labai stiprų žemės drebėjimą, patirdamas didelę žalą, bet nesugriudamas visame pasaulyje.7 On the other hand, it should remain operational for more frequent, but less severe seismic events.
Seisminio veikimo vertinimas
Inžinieriai turi žinoti kiekybinį faktinių ar numatomų seisminių charakteristikų lygį, susijusį su tiesiogine žala atskiram pastatui, kurį patiria tam tikras žemės drebėjimas. Toks vertinimas gali būti atliktas eksperimentiniu arba analitiniu būdu.
Eksperimentinis vertinimas
Experimental evaluations are expensive tests that are typically done by placing a (scaled) model of the structure on a papurtyti-stalą that simulates the earth shaking and observing its behavior.8 Such kinds of experiments were first performed more than a century ago.9 Only recently has it become possible to perform 1:1 scale testing on full structures.
Dėl brangaus tokių bandymų pobūdžio jie dažniausiai naudojami siekiant suprasti konstrukcijų seisminį elgesį, patvirtinti modelius ir tikrinti analizės metodus. Taigi, tinkamai patvirtinus, skaičiavimo modeliai ir skaitinės procedūros dažniausiai yra pagrindinė konstrukcijų seisminių savybių vertinimo našta.
Analitinis/Skaitinis vertinimas
Seisminio veikimo vertinimas or seisminė struktūrinė analizė is a powerful tool of earthquake engineering which utilizes detailed modelling of the structure together with methods of structural analysis to gain a better understanding of seismic performance of building and ne{0}}pastatų konstrukcijos. Technika kaip formali koncepcija yra palyginti neseniai sukurta.
In general, seismic structural analysis is based on the methods of struktūrinė dinamika.10 For decades, the most prominent instrument of seismic analysis has been the earthquake atsako spektras method which also contributed to the proposed building code's concept of today.11
However, such methods are good only for linear elastic systems, being largely unable to model the structural behavior when damage (i.e., ne{0}}tiesiškumas) appears. Numerical žingsnis{0}}po-integravimo proved to be a more effective method of analysis for multi-degree-of-freedom struktūrinės sistemos with significant ne{0}}tiesiškumas under a trumpalaikis process of ground motion excitation.12 Use of the baigtinių elementų metodas is one of the most common approaches for analyzing non-linear dirvožemio struktūros sąveika computer models.
Iš esmės skaitinė analizė atliekama siekiant įvertinti pastatų seismines charakteristikas. Našumo vertinimai paprastai atliekami naudojant netiesinę statinę stumdymo analizę arba netiesinę laiko{0}}istorijos analizę. Atliekant tokias analizes, labai svarbu pasiekti tikslų ne-tiesinį konstrukcinių komponentų, pvz., sijų, kolonų, sijų -kolonų sujungimų, šlyties sienų ir kt., modeliavimą. Taigi eksperimentiniai rezultatai vaidina svarbų vaidmenį nustatant atskirų komponentų modeliavimo parametrus, ypač tuos, kurie yra veikiami reikšmingų ne-tiesinių deformacijų. Tada atskiri komponentai surenkami, kad būtų sukurtas visas nelinijinis struktūros modelis. Taip sukurti modeliai analizuojami siekiant įvertinti pastatų eksploatacines savybes.
The capabilities of the structural analysis software are a major consideration in the above process as they restrict the possible component models, the analysis methods available and, most importantly, the numerical robustness. The latter becomes a major consideration for structures that venture into the non-linear range and approach global or local collapse as the numerical solution becomes increasingly unstable and thus difficult to reach. There are several commercially available Finite Element Analysis software's such as CSI-SAP2000 and CSI-PERFORM-3D, MTR/SASSI, Scia Engineer-ECtools, ABAQUS, and Ansys, all of which can be used for the seismic performance evaluation of buildings. Moreover, there is research-based finite element analysis platforms such as OpenSees, MASTODON, which is based on the MOOSE Framework, RUAUMOKO ir senesni DRAIN-2D/3D, iš kurių keli dabar yra atvirojo kodo.
Žemės drebėjimų inžinerijos tyrimai
Žemės drebėjimų inžinerijos tyrimai – tai tiek lauko, tiek analitinis tyrimas ar eksperimentavimas, skirtas su žemės drebėjimų inžinerija susijusiems faktams atrasti ir moksliškai paaiškinti, tradicinių koncepcijų peržiūrai atsižvelgiant į naujus atradimus ir sukurtų teorijų pritaikymui praktikoje.
The Nacionalinis mokslo fondas (NSF) is the main United States government agency that supports fundamental research and education in all fields of earthquake engineering. In particular, it focuses on experimental, analytical and computational research on design and performance enhancement of structural systems.
The Žemės drebėjimų inžinerijos tyrimų institutas (EERI) is a leader in dissemination of žemės drebėjimo inžineriniai tyrimai related information both in the U.S. and globally.
A definitive list of earthquake engineering research related drebantys stalai around the world may be found in Experimental Facilities for Earthquake Engineering Simulation Worldwide.14 The most prominent of them is now E-Defense Shake Table15 in Japonija.
Pagrindinės JAV tyrimų programos
NSF also supports the George E. Brown, Jr. Žemės drebėjimo inžinerinio modeliavimo tinklas
The NSF Hazard Mitigation and Structural Engineering program (HMSE) supports research on new technologies for improving the behaviour and response of structural systems subject to earthquake hazards; fundamental research on safety and reliability of constructed systems; innovative developments in analizė and model based simulation of structural behaviour and response including soil-structure interaction; design concepts that improve struktūros veikimas and flexibility; and application of new control techniques for structural systems.16
(NEES) that advances knowledge discovery and innovation for žemės drebėjimų and cunamis loss reduction of the nation's civil infrastructure and new experimental simulation techniques and instrumentation.17
NEES tinkle yra 14 geografiškai-paskirstytų, bendro naudojimo-laboratorijų, kurios palaiko kelių tipų eksperimentinius darbus:17 geotechnical centrifuge research, papurtyti-stalą tests, large-scale structural testing, tsunami wave basin experiments, and field site research.18 Participating universities include: Kornelio universitetas; Lehigho universitetas; Oregono valstijos universitetas; Rensselaer politechnikos institutas; Bafalo universitetas, Niujorko valstijos universitetas; Kalifornijos universitetas, Berklis; Kalifornijos universitetas, Davis; Kalifornijos universitetas, Los Andželas; Kalifornijos universitetas, San Diegas; Kalifornijos universitetas, Santa Barbara; Ilinojaus universitetas, Urbana{0}}Šampanas; Minesotos universitetas; Nevados universitetas, Reno; and the Teksaso universitetas, Ostinas.17
The equipment sites (labs) and a central data repository are connected to the global earthquake engineering community via the NEEShub website. The NEES website is powered by HUBzero software developed at Purdue universitetas for nanoHUB specifically to help the scientific community share resources and collaborate. The cyberinfrastructure, connected via Internetas 2, teikia interaktyvius modeliavimo įrankius, modeliavimo įrankių kūrimo sritį, kuruojamą centrinę duomenų saugyklą, animuotus pristatymus, naudotojų palaikymą, nuotolinį dalyvavimą, išteklių įkėlimo ir dalijimosi mechanizmą bei statistiką apie vartotojus ir naudojimo būdus.
Ši kibernetinė infrastruktūra leidžia tyrėjams: saugiai saugoti, tvarkyti ir dalytis duomenimis standartizuotoje sistemoje centrinėje vietoje; nuotoliniu būdu stebėti ir dalyvauti eksperimentuose naudojant sinchronizuotus duomenis ir vaizdo įrašus realiuoju laiku; bendradarbiauti su kolegomis, kad būtų lengviau planuoti, atlikti, analizuoti ir publikuoti tyrimų eksperimentus; ir atlikti skaičiavimo ir hibridinius modeliavimus, kurie gali sujungti kelių paskirstytų eksperimentų rezultatus ir susieti fizinius eksperimentus su kompiuteriniais modeliavimais, kad būtų galima ištirti bendrą sistemos našumą.
Šie ištekliai kartu suteikia bendradarbiavimo ir atradimų priemones, siekiant pagerinti civilinės ir mechaninės infrastruktūros sistemų seisminį projektavimą ir veikimą.
Žemės drebėjimo modeliavimas
The very first žemės drebėjimo modeliavimas were performed by statically applying some horizontalios inercijos jėgos based on masteliu didžiausių žemės pagreičių to a mathematical model of a building.19 With the further development of computational technologies, statinis approaches began to give way to dinamiškas ones.
Dynamic experiments on building and non-building structures may be physical, like suplakti{0}}stalo testavimas, or virtual ones. In both cases, to verify a structure's expected seismic performance, some researchers prefer to deal with so called "real time-histories" though the last cannot be "real" for a hypothetical earthquake specified by either a building code or by some particular research requirements. Therefore, there is a strong incentive to engage an earthquake simulation which is the seismic input that possesses only essential features of a real event.
Kartais žemės drebėjimo modeliavimas suprantamas kaip stipraus žemės drebėjimo{0}}vietinio poveikio atkūrimas.
Struktūros modeliavimas
Theoretical or experimental evaluation of anticipated seismic performance mostly requires a struktūros modeliavimas which is based on the concept of structural likeness or similarity. Panašumas is some degree of analogija or panašumo between two or more objects. The notion of similarity rests either on exact or approximate repetitions of modelius in the compared items.
In general, a building model is said to have similarity with the real object if the two share geometrinis panašumas, kinematinis panašumas and dinaminis panašumas. The most vivid and effective type of similarity is the kinematinė one. Kinematinis panašumas exists when the paths and velocities of moving particles of a model and its prototype are similar.
The ultimate level of kinematinis panašumas is kinematinis ekvivalentiškumas when, in the case of earthquake engineering, time-histories of each story lateral displacements of the model and its prototype would be the same.
Seisminės vibracijos valdymas
Seisminės vibracijos valdymas is a set of technical means aimed to mitigate seismic impacts in building and ne-pastatas structures. All seismic vibration control devices may be classified as pasyvus, aktyvus or hibridas21 where:
pasyvaus valdymo įtaisai have no Atsiliepimas capability between them, structural elements and the ground;
aktyvaus valdymo įtaisai incorporate real-time recording instrumentation on the ground integrated with earthquake input processing equipment and pavaros within the structure;
hibridiniai valdymo įrenginiai have combined features of active and passive control systems.22
When ground seisminės bangos reach up and start to penetrate a base of a building, their energy flow density, due to reflections, reduces dramatically: usually, up to 90 percent . However, the remaining portions of the incident waves during a major earthquake still bear a huge devastating potential.
After the seismic waves enter a antstatas, there are a number of ways to control them in order to soothe their damaging effect and improve the building's seismic performance, for instance:
to išsisklaidyti the wave energy inside a antstatas with properly engineered amortizatoriai;
išsklaidyti bangų energiją tarp platesnių dažnių diapazonų;
to sugerti the rezonansinis portions of the whole wave frequencies band with the help of so-called masės slopintuvai.23
Paskutinio tipo įrenginiai, atitinkamai sutrumpintai kaip TMD, reiškiantys suderintą (pasyvus), as AMD for the aktyvus, and as HMD for the hibridiniai masės slopintuvai, have been studied and installed in aukštybiniai{0}} pastatai, daugiausia Japonijoje, ketvirtį amžiaus.24
However, there is quite another approach: partial suppression of the seismic energy flow into the antstatas known as seismic or pagrindo izoliacija.
For this, some pads are inserted into or under all major load-carrying elements in the base of the building which should substantially decouple a antstatas from its substruktūra resting on a shaking ground.
The first evidence of earthquake protection by using the principle of base isolation was discovered in Pasargadae, miestas senovės Persijoje, dabartinis Iranas, datuojamas VI amžiuje prieš Kristų. Žemiau yra keletas šiuolaikinių seisminės vibracijos valdymo technologijų pavyzdžių.
Sausos{0}}akmeninės sienos Peru
Peru is a highly seisminis land; for centuries the dry-stone statyba proved to be more earthquake-resistant than using mortar. People of Inkų civilizacija were masters of the polished 'dry-stone walls', called ashlar, where blocks of stone were cut to fit together tightly without any skiedinys. Inkai buvo vieni geriausių pasaulyje kada nors matytų akmentašių25 and many junctions in their masonry were so perfect that even blades of grass could not fit between the stones.
The stones of the dry-stone walls built by the Incas could move slightly and resettle without the walls collapsing, a passive struktūrinė kontrolė technique employing both the principle of energy dissipation (coulomb damping) and that of suppressing rezonansinis amplifications.26
Sureguliuotas masės slopintuvas
Typically the sureguliuoti masės slopintuvai are huge concrete blocks mounted in dangoraižiai or other structures and move in opposition to the rezonanso dažnis oscillations of the structures by means of some sort of spring mechanism.
The Taipėjus 101 skyscraper needs to withstand taifūnas winds and earthquake drebulys common in this area of Asia/Pacific. For this purpose, a steel švytuoklė weighing 660 metric tonnes that serves as a tuned mass damper was designed and installed atop the structure. Suspended from the 92nd to the 88th floor, the pendulum sways to decrease resonant amplifications of lateral displacements in the building caused by earthquakes and strong gūsiai.
Isteretiniai amortizatoriai
A isteretinis slopintuvas is intended to provide better and more reliable seismic performance than that of a conventional structure by increasing the dissipation of seisminis įėjimas energy.27 There are five major groups of hysteretic dampers used for the purpose, namely:
Skysčio klampus slopintuvai (FVD)
Viscous Dampers pranašumas yra tai, kad jie yra papildoma slopinimo sistema. Jie turi ovalią histeretinę kilpą, o slopinimas priklauso nuo greičio. Nors gali prireikti nedidelės priežiūros, klampių amortizatorių paprastai nereikia keisti po žemės drebėjimo. Nors jie yra brangesni už kitas slopinimo technologijas, jie gali būti naudojami tiek seisminėms, tiek vėjo apkrovoms ir yra dažniausiai naudojami isteretiniai slopintuvai.28
Trinties slopintuvai (FD)
Friction dampers tend to be available in two major types, linear and rotational and dissipate energy by heat. The damper operates on the principle of a kulono slopintuvas. Depending on the design, friction dampers can experience klijavimo-reiškinys and Šaltasis suvirinimas. Pagrindinis trūkumas yra tas, kad trinties paviršiai laikui bėgant gali susidėvėti, todėl jie nerekomenduojami vėjo apkrovoms išsklaidyti. Naudojant seisminėse srityse, susidėvėjimas nesukelia problemų ir nereikia priežiūros. Jie turi stačiakampę isteretinę kilpą ir tol, kol pastatas yra pakankamai elastingas, po žemės drebėjimo jie linkę grįžti į pradinę padėtį.
Metalinės sklendės (MYD)
Metallic yielding dampers, as the name implies, yield in order to absorb the earthquake's energy. This type of damper absorbs a large amount of energy however they must be replaced after an earthquake and may prevent the building from settling back to its original position.
Viskoelastiniai amortizatoriai (VED)
Viskoelastiniai slopintuvai naudingi tuo, kad gali būti naudojami tiek vėjui, tiek seisminėms reikmėms, dažniausiai apsiriboja nedideliu poslinkiu. Susirūpinimą kelia technologijos patikimumas, nes kai kurių prekių ženklų naudojimas pastatuose Jungtinėse Valstijose buvo uždraustas.
Svyruojantys švytuokliniai amortizatoriai (sūpynės)
Pagrindo izoliacija
Pagrindo izoliacija siekiama užkirsti kelią kinetinės žemės drebėjimo energijos perkėlimui į elastinę energiją pastate. Šios technologijos tai daro izoliuodamos konstrukciją nuo žemės, taip suteikdamos jiems galimybę šiek tiek savarankiškai judėti. Energijos perdavimo į konstrukciją laipsnis ir energijos išsklaidymo būdas skirsis priklausomai nuo naudojamos technologijos.
Švininis guminis guolis
Lead rubber bearing or LRB is a type of pagrindo izoliacija employing a heavy slopinimas. It was invented by Billas Robinsonas, Naujoji Zelandija.29
Heavy damping mechanism incorporated in vibracijos valdymas technologies and, particularly, in base isolation devices, is often considered a valuable source of suppressing vibrations thus enhancing a building's seismic performance. However, for the rather pliant systems such as base isolated structures, with a relatively low bearing stiffness but with a high damping, the so-called "damping force" may turn out the main pushing force at a strong earthquake. The video30 shows a Lead Rubber Bearing being tested at the UCSD Caltrans-SRMD facility. The bearing is made of rubber with a lead core. It was a uniaxial test in which the bearing was also under a full structure load. Many buildings and bridges, both in New Zealand and elsewhere, are protected with lead dampers and lead and rubber bearings. Te Papa Tongarewa, the national museum of New Zealand, and the New Zealand Parlamento pastatai have been fitted with the bearings. Both are in Velingtonas which sits on an aktyvus gedimas.29
Spyruoklės-su-amortizatoriaus pagrindo izoliatoriumi
Springs-with-damper base isolator installed under a three-story town-house, Santa Monika, California is shown on the photo taken prior to the 1994 Northridge žemės drebėjimas exposure. It is a pagrindo izoliacija device conceptually similar to Švininis guminis guolis.
One of two three-story town-houses like this, which was well instrumented for recording of both vertical and horizontal pagreičiai on its floors and the ground, has survived a severe shaking during the Northridge žemės drebėjimas and left valuable recorded information for further study.
Paprastas ritininis guolis
Simple roller bearing is a pagrindo izoliacija device which is intended for protection of various building and non-building structures against potentially damaging šoniniai smūgiai of strong earthquakes.
This metallic bearing support may be adapted, with certain precautions, as a seismic isolator to skyscrapers and buildings on soft ground. Recently, it has been employed under the name of metalinis ritininis guolis for a housing complex (17 stories) in Tokijas, Japonija.31
Frikcinis švytuoklinis guolis
Friction pendulum bearing (FPB) is another name of trinties švytuoklės sistema (FPS). It is based on three pillars:32
šarnyrinis trinties slankiklis;
sferinis įgaubtas slydimo paviršius;
apgaubiantis cilindras šoninio poslinkio suvaržymui.
Snapshot with the link to video clip of a papurtyti-stalą testing of FPB system supporting a rigid building model is presented at the right.
Seisminis dizainas
Seisminis dizainas is based on authorized engineering procedures, principles and criteria meant to dizainas or modernizuoti structures subject to earthquake exposure.19 Those criteria are only consistent with the contemporary state of the knowledge about žemės drebėjimo inžineriniai statiniai.33 Therefore, a building design which exactly follows seismic code regulations does not guarantee safety against collapse or serious damage.34
The price of poor seismic design may be enormous. Nevertheless, seismic design has always been a bandymas ir klaida process whether it was based on physical laws or on empirical knowledge of the struktūrinis veikimas of different shapes and materials.
To practice seisminis dizainas, seismic analysis or seismic evaluation of new and existing civil engineering projects, an inžinierius should, normally, pass examination on Seisminiai principai35 which, in the State of California, include:
Seisminiai duomenys ir seisminio projektavimo kriterijai
Inžinerinių sistemų seisminės charakteristikos
Seisminės jėgos
Seisminės analizės procedūros
Seisminis detalizavimas ir statybos kokybės kontrolė
Kurti sudėtingas struktūrines sistemas,36 seismic design largely uses the same relatively small number of basic structural elements (to say nothing of vibration control devices) as any non-seismic design project.
Normally, according to building codes, structures are designed to "withstand" the largest earthquake of a certain probability that is likely to occur at their location. This means the loss of life should be minimized by preventing collapse of the buildings.
Seismic design is carried out by understanding the possible gedimo režimai of a structure and providing the structure with appropriate stiprumas, standumas, plastiškumas, and konfigūracija37 to ensure those modes cannot occur.
Seisminio projektavimo reikalavimai
Seisminio projektavimo reikalavimai depend on the type of the structure, locality of the project and its authorities which stipulate applicable seismic design codes and criteria.7 For instance, Kalifornijos transporto departamentas's requirements called Seisminio projektavimo kriterijai (SDC) and aimed at the design of new bridges in California38 incorporate an innovative seismic performance-based approach.
The most significant feature in the SDC design philosophy is a shift from a priverstiniu{0}}pagrįstu vertinimu of seismic demand to a poslinkiu{0}}pagrįstas įvertinimas of demand and capacity. Thus, the newly adopted displacement approach is based on comparing the elastinis poslinkis demand to the neelastingas poslinkis capacity of the primary structural components while ensuring a minimum level of inelastic capacity at all potential plastic hinge locations.
In addition to the designed structure itself, seismic design requirements may include a žemės stabilizavimas underneath the structure: sometimes, heavily shaken ground breaks up which leads to collapse of the structure sitting upon it.40 The following topics should be of primary concerns: liquefaction; dynamic lateral earth pressures on retaining walls; seismic slope stability; earthquake-induced settlement.41
Branduoliniai įrenginiai should not jeopardise their safety in case of earthquakes or other hostile external events. Therefore, their seismic design is based on criteria far more stringent than those applying to non-nuclear facilities.42 The Fukušimos I branduolinės avarijos and žalą kitiems branduoliniams objektams that followed the 2011 Tōhoku earthquake and tsunami have, however, drawn attention to ongoing concerns over Japonijos branduolinio seisminio projektavimo standartai and caused many other governments to iš naujo{0}}įvertinti savo branduolines programas. Doubt has also been expressed over the seismic evaluation and design of certain other plants, including the Fesenheimo atominė elektrinė in France.
Gedimų režimai
Gedimo režimo is the manner by which an earthquake induced failure is observed. It, generally, describes the way the failure occurs. Though costly and time consuming, learning from each real earthquake failure remains a routine recipe for advancement in seisminis dizainas methods. Below, some typical modes of earthquake-generated failures are presented.
The lack of stiprinimas coupled with poor skiedinys and inadequate roof-to-wall ties can result in substantial damage to an nesutvirtintas mūrinis pastatas. Smarkiai įtrūkusios arba pasvirusios sienos yra viena iš labiausiai paplitusių žemės drebėjimo pažeidimų. Taip pat pavojinga yra žala, kuri gali atsirasti tarp sienų ir stogo arba grindų diafragmų. Atskyrimas tarp karkaso ir sienų gali kelti pavojų vertikaliai stogo ir grindų sistemų atramai.
Minkštos istorijos efektas. Absence of adequate stiffness on the ground level caused damage to this structure. A close examination of the image reveals that the rough board siding, once covered by a plytų fanera, has been completely dismantled from the studwall. Only the standumas of the floor above combined with the support on the two hidden sides by continuous walls, not penetrated with large doors as on the street sides, is preventing full collapse of the structure.
Dirvožemio suskystinimas. In the cases where the soil consists of loose granular deposited materials with the tendency to develop excessive hydrostatic pore water pressure of sufficient magnitude and compact, suskystinimas of those loose saturated deposits may result in non-uniform gyvenvietės and tilting of structures. This caused major damage to thousands of buildings in Niigata, Japan during the 1964 metų žemės drebėjimas.43
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Nuošliaužos uolų griūtis. A nuošliauža is a geological phenomenon which includes a wide range of ground movement, including uolų kriokliai. Typically, the action of gravitacija is the primary driving force for a landslide to occur though in this case there was another contributing factor which affected the original šlaito stabilumas: the landslide required an žemės drebėjimo sukėlėjas before being released.
Smūgis į gretimą pastatą. This is a photograph of the collapsed five-story tower, St. Joseph's Seminary, Los Altosas, Kalifornija which resulted in one fatality. During Loma Prieta žemės drebėjimas, the tower pounded against the independently vibrating adjacent building behind. A possibility of pounding depends on both buildings' lateral displacements which should be accurately estimated and accounted for.
At Northridge žemės drebėjimas, the Kaiser Permanente concrete frame office building had joints completely shattered, revealing netinkamas uždarymo plienas, which resulted in the second story collapse. In the transverse direction, composite end kirpimo sienos, consisting of two wythes of brick and a layer of šratinio betono that carried the lateral load, peeled apart because of netinkamas per{0}}ryšius and failed.
Improper statybvietė on a papėdė.
Poor detailing of the stiprinimas (lack of concrete confinement in the columns and at the beam-column joints, inadequate splice length).
Seismically weak švelni istorija at the first floor.
Long konsolės with heavy negyvas krovinys.
Slystančių pamatų efektas of a relatively rigid residential building structure during 1987 m. Whittier Narrows žemės drebėjimas. The magnitude 5.9 earthquake pounded the Garvey West Apartment building in Monterey Park, California and shifted its antstatas about 10 inches to the east on its foundation.
If a superstructure is not mounted on a pagrindo izoliacija system, its shifting on the basement should be prevented.
Gelžbetonis column burst at Northridge žemės drebėjimas due to nepakankamas šlyties sutvirtinimo režimas which allows main reinforcement to sagtis outwards. The deck unseated at the vyris and failed in shear. As a result, the La Cienega-Venice požeminė perėja section of the 10 Freeway collapsed.
Loma Prieta žemės drebėjimas: side view of reinforced concrete palaikymo-stulpelių gedimas which triggered viršutinis denis griūva ant apatinio denio of the two-level Cypress viaduct of Interstate Highway 880, Oakland, CA.
Atraminės sienos gedimas at Loma Prieta žemės drebėjimas in Santa Cruz Mountains area: prominent northwest-trending extensional cracks up to 12 cm (4.7 in) wide in the concrete išsiliejimas to Austrian Dam, the north atrama.
Ground shaking triggered dirvožemio suskystinimas in a subsurface layer of smėlis, producing differential lateral and vertical movement in an overlying karkasas of unliquified sand and dumblas. This žemės gedimo būdas, termed šoninis plitimas, yra pagrindinė suskystėjimu{0}}susijusios žemės drebėjimo žalos priežastis.44
Severely damaged building of Agriculture Development Bank of China after 2008 metų Sičuano žemės drebėjimas: most of the sijos ir prieplaukos kolonos yra nukirptos. Large diagonal cracks in masonry and veneer are due to in-plane loads while abrupt atsiskaitymas of the right end of the building should be attributed to a sąvartynas which may be hazardous even without any earthquake.45
Dvigubas cunamio poveikis: jūros bangos hydraulic spaudimas and potvynis. Thus, Indijos vandenyno žemės drebėjimas of December 26, 2004, with the epicentras off the west coast of Sumatra, Indonesia, triggered a series of devastating tsunamis, killing more than 230,000 people in eleven countries by užtvindęs aplinkines pakrantės bendruomenes didžiulėmis bangomis up to 30 meters (100 feet) high.47
Žemės drebėjimui{0}}atspari konstrukcija
Žemės drebėjimo statyba means implementation of seisminis dizainas to enable building and non-building structures to live through the anticipated earthquake exposure up to the expectations and in compliance with the applicable statybos kodeksus.
Dizainas ir statyba yra glaudžiai susiję. Norint pasiekti gerą darbo kokybę, išsami informacija apie narius ir jų ryšius turėtų būti kuo paprastesnė. Kaip ir bet kuri statyba apskritai, žemės drebėjimo statyba yra procesas, kurį sudaro infrastruktūros pastatymas, modernizavimas arba surinkimas, atsižvelgiant į turimas statybines medžiagas.48
The destabilizing action of an earthquake on constructions may be tiesioginis (seismic motion of the ground) or netiesioginis (earthquake-induced landslides, dirvožemio suskystinimas and waves of tsunami).
Struktūra gali atrodyti kaip stabili, tačiau įvykus žemės drebėjimui gali kelti tik pavojų.49 The crucial fact is that, for safety, earthquake-resistant construction techniques are as important as kokybės kontrolė and using correct materials. Žemės drebėjimo rangovas should be registruotas in the state/province/country of the project location (depending on local regulations), surištas and apdraustasisreikalinga citata.
To minimize possible nuostoliai, statybos procesas turėtų būti organizuojamas turint omenyje, kad žemės drebėjimas gali smogti bet kuriuo metu iki statybų pabaigos.
Each statybos projektas requires a qualified team of professionals who understand the basic features of seismic performance of different structures as well as statybos valdymas.
Adobe struktūros
Around thirty percent of the world's population lives or works in earth-made construction.50 Adobe type of purvo plytos is one of the oldest and most widely used building materials. The use of Adobe is very common in some of the world's most hazard-prone regions, traditionally across Latin America, Africa, Indian subcontinent and other parts of Asia, Middle East and Southern Europe.
„Adobe“ pastatai laikomi labai pažeidžiamais stiprių drebėjimų metu.51 However, multiple ways of seismic strengthening of new and existing adobe buildings are available.52
Pagrindiniai veiksniai, padedantys pagerinti „Adobe“ konstrukcijos seisminį efektyvumą, yra šie:
Statybos kokybė.
Kompaktiškas, dėžutės{0}}tipo išdėstymas.
Seisminis sutvirtinimas.53
Klinties ir smiltainio konstrukcijos
Kalkakmenis is very common in architecture, especially in North America and Europe. Many landmarks across the world are made of limestone. Many medieval churches and castles in Europe are made of kalkakmenis and smiltainis masonry. They are the long-lasting materials but their rather heavy weight is not beneficial for adequate seismic performance.
Application of modern technology to seismic retrofitting can enhance the survivability of unreinforced masonry structures. As an example, from 1973 to 1989, the Solt Leik Sičio ir apygardos pastatas in Juta was exhaustively renovated and repaired with an emphasis on preserving historical accuracy in appearance. This was done in concert with a seismic upgrade that placed the weak sandstone structure on base isolation foundation to better protect it from earthquake damage.
Medinės karkasinės konstrukcijos
Medinis karkasas dates back thousands of years, and has been used in many parts of the world during various periods such as ancient Japan, Europe and medieval England in localities where timber was in good supply and building stone and the skills to work it were not.
The use of medinis karkasas in buildings provides their complete skeletal framing which offers some structural benefits as the timber frame, if properly engineered, lends itself to better seisminis išgyvenamumas.54
Lengvos{0}}rėmo konstrukcijos
Lengvos{0}}rėmo konstrukcijos usually gain seismic resistance from rigid fanera shear walls and wood structural panel diafragmos.55 Special provisions for seismic load-resisting systems for all sukonstruota mediena structures requires consideration of diaphragm ratios, horizontal and vertical diaphragm shears, and jungtis/tvirtinimo detalė values. In addition, collectors, or drag struts, to distribute shear along a diaphragm length are required.
Sustiprintos mūro konstrukcijos
A construction system where plieno armatūra is embedded in the skiedinio siūlės of mūro or placed in holes and that are filled with betono or skiedinys is called sustiprintas mūras.56 There are various practices and techniques to reinforce masonry. The most common type is the reinforced tuščiavidurių vienetų mūras.
To achieve a plastiškas behavior in masonry, it is necessary that the šlyties stiprumas of the wall is greater than the lenkimo stiprumas.57 The effectiveness of both vertical and horizontal reinforcements depends on the type and quality of the masonry units and skiedinys.
The devastating 1933 m. Long Byčo žemės drebėjimas revealed that masonry is prone to earthquake damage, which led to the Kalifornijos valstijos kodas making masonry reinforcement mandatory across California.
Gelžbetoninės konstrukcijos
Gelžbetonis is concrete in which steel reinforcement bars (armatūros strypai) or skaidulų have been incorporated to strengthen a material that would otherwise be trapus. It can be used to produce sijos, stulpelius, grindys ar tiltai.
Iš anksto įtemptas betonas is a kind of gelžbetonis used for overcoming concrete's natural weakness in tension. It can be applied to sijos, floors or bridges with a longer span than is practical with ordinary reinforced concrete. Prestressing sausgyslės (generally of high tensile steel cable or rods) are used to provide a clamping load which produces a gniuždymo įtempis that offsets the tempimo įtempis that the concrete suspaudimo elementas would, otherwise, experience due to a bending load.
To prevent catastrophic collapse in response earth shaking (in the interest of life safety), a traditional reinforced concrete frame should have plastiškas joints. Depending upon the methods used and the imposed seismic forces, such buildings may be immediately usable, require extensive repair, or may have to be demolished.
Iš anksto įtemptos konstrukcijos
Iš anksto įtempta konstrukcija is the one whose overall vientisumas, stabilumas and saugumo depend, primarily, on a išankstinis įtempimas. Išankstinis įtempimas means the intentional creation of permanent stresses in a structure for the purpose of improving its performance under various service conditions.58
Yra šie pagrindiniai išankstinio įtempimo tipai:
Išankstinis-suspaudimas (dažniausiai su savo konstrukcijos svoriu)
Įtempimas with high-strength embedded tendons
Po-įtempimo with high-strength bonded or unbonded tendons
Today, the concept of iš anksto įtempta konstrukcija is widely engaged in design of pastatai, underground structures, TV towers, power stations, floating storage and offshore facilities, branduolinis reaktorius vessels, and numerous kinds of tiltas systems.59
A beneficial idea of išankstinis įtempimas was, apparently, familiar to the ancient Rome architects; look, e.g., at the tall mansarda wall of Koliziejus working as a stabilizing device for the wall prieplaukos beneath.
Plieninės konstrukcijos
Plieninės konstrukcijos are considered mostly earthquake resistant but some failures have occurred. A great number of welded plieno momentams{0}}atsparus rėmas buildings, which looked earthquake-proof, surprisingly experienced brittle behavior and were hazardously damaged in the 1994 m. Northridge žemės drebėjimas.60 After that, the Federalinė ekstremalių situacijų valdymo agentūra (FEMA) initiated development of repair techniques and new design approaches to minimize damage to steel moment frame buildings in future earthquakes.61
For konstrukcinis plienas seismic design based on Apkrovos ir pasipriešinimo faktoriaus dizainas (LRFD) approach, it is very important to assess ability of a structure to develop and maintain its bearing resistance in the neelastingas range. A measure of this ability is plastiškumas, which may be observed in a pati medžiaga, in a konstrukcinis elementas, or to a visa struktūra.
As a consequence of Northridge žemės drebėjimas experience, the American Institute of Steel Construction has introduced AISC 358 "Pre-Qualified Connections for Special and intermediate Steel Moment Frames." The AISC Seismic Design Provisions require that all Plieniniai momentams atsparūs rėmai employ either connections contained in AISC 358, or the use of connections that have been subjected to pre-qualifying cyclic testing.62
Žemės drebėjimo nuostolių prognozavimas
Žemės drebėjimo nuostolių įvertinimas is usually defined as a Žalos koeficientas (DR) which is a ratio of the earthquake damage repair cost to the Bendra vertė of a building.63 Tikėtinas didžiausias nuostolis (PML) is a common term used for earthquake loss estimation, but it lacks a precise definition. In 1999, ASTM E2026 'Standard Guide for the Estimation of Building Damageability in Earthquakes' was produced in order to standardize the nomenclature for seismic loss estimation, as well as establish guidelines as to the review process and qualifications of the reviewer.64
Earthquake loss estimations are also referred to as Seisminės rizikos vertinimai. Rizikos vertinimo procesas paprastai apima įvairių žemės judesių, kartu su pastato pažeidžiamumu ar pažeidimu, tikimybę, kai judesi žemė. Rezultatai apibrėžiami kaip pastato atkuriamosios vertės procentas.65