MAURER MAURER EarthquakeSeismic Protection Systems .

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MAURER SeismicProtection SystemsMAUREREarthquakeProtection SystemsAs unique as the buildings they protectforces in motion

MAURER EarthquakeProtection SystemsContentStructural Protection Systems P. 04Structural Analysis P. 05Basic Concepts ofEarthquake Protection P. 06Hydraulic Coupling andDamping Elements Permanent Restraints(HK; HKE) Shock Transmission Unit(MSTU) Shock Transmitter withLoad Limiter (MSTL) P. 08P. 08P. 08P. 08Bearing Elements forBase Isolation Elastomeric Isolators Sliding Isolators Hydraulic Dampers (MHD) P. 10P. 10P. 12P. 14Steel Hysteretic Dampers P. 16Structural Expansion Joints Earthquake ExpansionJoints for Road Bridges Swivel-Joist ExpansionJoints of Type DS Fuse Box for ModularJoints P. 18Project-Specific Testing P. 22References P. 25P. 18P. 20P. 21 2010 by DC TOWERS DONAU-CITY2

MAURER Structural Protection Systems– as unique as the buildings they protect “Earthquakes are natural disasters whose feature isthat most of the human and economic losses are not due tothe earthquake mechanisms, but to failures in man-madefacilities, like buildings, bridges etc., which supposedly weredesigned and constructed for the comfort of the humanbeings.” (Bertero)The above observation brings a note of optimism and isencouraging because it tells us that, in the long run, seismicproblems are solvable in principle. The task of solvingthese problems is attributed to Seismic Engineering. Theadvances in this field have already played a significant role inreducing seismic hazards through the improvement of thebuilt environment, finally making possible the design andconstruction of earthquake-resistant structures. Progress hasmainly been the result of newly developed design strategiese.g. Base Isolation, which could not have found usefulapplication without the parallel development of the “seismichardware” needed for their implementation.Thus, several research laboratories and industrialconcerns have invented and perfected a series of devices thatexploit well known physical phenomena which have beenadapted to the protection of structures.MAURER has distinguished itself in this very real race, whenin the middle of the 1990s we decided to invest both humanand financial resources, that have significant led to itspresent position of worldwide leadership. The purpose of this brochure is:A) to illustrate the manner in whichMAURER has faced and solved theproblems deriving from the practicalapplication of the new design strategies.B) to present the devices that havebeen developed and perfected towardsthis goal.World map of the mostaffected earthquake zonesMAURER has adopted the strategy ofsizing its devices on a case-by-casebasis, i.e. the “tailor-made” philosophy,with evident advantages for thecustomer.Acropolis Museum,Athens3

Structural Protection SystemsMAURER is more than a supplier of Seismic HardwareMAURER has acquired a vast experience in the applicationof modern seismic protection technologies within a widevariety of structures to minimise earthquake induced damage.MAURER’s experts offer structural designers and architectsassistance in the definition of the protection systems and inthe selection of devices best suited for each case, consideringnot only the seismicity of the site, but also the structural,functional and architectural needs of the works.Isolated building, ONASSIS Home ofLetters and Fine Arts, Athens. Earthquakeprotection with isolators in the basementThe quality and efficiency of the proposed protection systems are validated via the most up-to-date methods of computermodelling. Better adaptation thanks to a wider range of Seismic HardwareThe more types of seismic devices a designer has to choosefrom, the better he can adapt his solution. MAURER offersthe world‘s most extensive range of seismic devices. Ourspecialists always develop the best earthquake protectionsystem for your requirements.4

Structural AnalysisSeismic Analysis – a tool to develop through our devices yourSeismic Protection SystemThe linear (or modal) analysis represents the most commonly applied method to evaluate the effects (forces, deformations etc.)of an earthquake. The seismic input in this case is the “elastic response spectrum”. However, we can resort to this procedure onlyif a set of conditions are met. The most important of them being the effective damping ratio must be less than 30 %. One of themajor drawbacks of the linear analysis is the inability to verify whether or not the isolation system possesses an adequateRe-Centring capability.With the non-linear (time history) analysis, we can better validate and optimize the structural protection system, taking intoaccount all local conditions. The seismic input in this case consists of a set of ground motion time-histories (accelerogrames).To conduct the non-linear analyses the following data is required: Structural dataStructural drawings, cross sections (deck, abutment, pier),moment of inertia, torsion constant, shear stiffness,materials (modulus of elasticity, shear modulus, density,etc.), foundation (dimensions, Winkler-modulus, etc). Earthquake dataResponse spectrum and/or representative accelerogrames,loads under seismic conditions, allowable bending moments,shear and axial forces, displacements and any further specificrequirements of the designer.Axonometric view of a rail-way bridge,3D mathematical model The advantages of the MAURER Non-linear Structural AnalysisAccurate determination of structural displacementsincluding torsional effects.Precise evaluation of actual safety margins withinthe structure and the seismic devices.Accurate calculation of response forces that affectthe elements and the structure as a whole.Validation of designer’s analysis through thecomparison with MAURER’s results.Optimization of seismic protection system in termsof efficiency and economy.Precise evaluation of the isolation system’sRe-Centring capability.Evaluation of considerable structural cost savingsbased on less reinforcement and savings in terms ofsteel and concrete.5

Basic Concepts of Earthquake ProtectionStructural protection through two basic conceptsof earthquake protectionHaving once established the level of protection required, the seismic engineer must make certain strategic choices anddepending on the type of structure, the seismicity and geological nature of the site, the norms currently in force, etc. .Today, seismic engineers can rely upon numerous solutions and relevant types of seismic devices that have already beensuccessfully adopted with success within the last three decades. These solutions can be grouped into two main types: 1. Provide the structural members with sufficientflexibility, strength and ductility to absorb and partiallydissipate the energy through the intrinsic viscousmechanism; these solutions are referred to as“strengthening” or “conventional design” approaches. 2. Aim at protecting the structure againstearthquake damage by limiting the seismic effects(rather than resisting them) through the use of devicesproperly inserted into the structure; this approach isusually referred to as “seismic mitigation”. Here below the flowchart places into perspective the design choices and the different types of anti-seismic devices that allowtheir practical aryDesign strategiesSeismic sHydraulicDampersHystereticDampersIncreasing energy dissipation capacity of seismic hardware StrengtheningThe design engineer who has selected the adoption of traditional techniques, essentially consisting in strengthening thestructure – has before him two possible alternatives: 1. Fit the structure with permanent restraints only,proportioning its structural members with adequateflexibility, resistance and ductility. 2. Insert at appropriate locations of the structuretemporary restraint devices, which allow slow thermalmovements and lock-up for impact when an earthquakeoccurs.The superior seismic behavior of hyperstatic structures, and bridges in particular, is well known. The simple explanation for thisfact is that in hyperstatic structures, all structural members are forced to work together at a critical moment. However, especiallyin the case of bridges, construction techniques e.g. prefabricated beams and the risk of occurrence of differential settling on thefoundations often suggest the choice of isostatic arrangements. The advantages of the two concepts can be maintained throughthe adoption of Hydraulic shock transmitters.6

Basic Concepts of Earthquake Protection MitigationIn the bar chart the alternative to structural reinforcement is Seismic Mitigation, which is the most effective design approach forprotecting structures erected in earthquake prone zones. The latter can be obtained through:– Seismic Isolation,– Energy Dissipation, or, better of a– combination of both.––––aIncreasingdampingSeismic isolation is by far the most used design approach toreduce the seismic response following an earthquake impact,that is to say, to mitigate its disastrous effects. A properisolation system must be capable of appropriately ensuringthe following four main functions occur:Period ShiftagTransmission of vertical loadsLateral flexibilityRe-Centring capabilityEnergy dissipationTBTCSome types of isolators intrinsically possess this function.For others, we must resort to the so-called “Fuse Restraints”.MAURER has developed several types of both mechanical andhydraulic.Comparison between acceleration in aconventional and an isolated structureIf the adoption of Seismic Isolation is not feasible and thestructure possesses sufficient flexibility i.e. important relativedisplacements occur during an earthquake due to elasticdeformation of its structural elements then Energy Dissipation(damping) can be effectively used to attain Seismic Mitigation.This is achieved through the adoption of Hysteretic DampersAcceleration [g]Some specialists also list a fifth fundamental function, namely:– Stiffness under service ime [s]or Hydraulic Dampers, which are inserted into the structure atappropriate locations. Skilled MAURER engineers are availableto assist designers in choosing the most appropriate SeismicHardware on a case-by-case basis, as well as optimizing theadopted solution in terms of costs, performance, reliability,durability etc. KSP Jürgen Engel Architekten, Krebs & Kiefer InternationalDjamaâ El Djazïr Mosque, Algiers7

Hydraulic Coupling and Damping ElementsMAURER Restraint Systems for Strengthening Permanent Restraints (HK; HKE)Even if permanent restraints represent the family of theconceptually simplest seismic hardware, nonetheless theycomprise a large variety of devices. Thus their standardizationis problematic and MAURER has adopted the strategy of the“tailor-made” design according to the specifications given bythe designers. These restraints can be designed to laterally fixthe structure in X and Y direction (HK device) or guide it in onedirection (unidirectional HKE device) only.Russkiy IslandBridge, laterallyfixed andlongitudinallymovable permanentrestraint-HKE forFy of 20 MN andtemporary duringconstruction forFx of 25 MN Shock Transmission Unit (MSTU)Shock Transmitters are devices that allow slow movements ( 0.1 mm/s) without appreciable resistance (1–4 % of Fmax), butprevent those of sudden onset without appreciable deformations (0.5–3 % of stroke capacity in loaded direction). Characteristic curves of Shock Transmitter types MSTU and MSTLlog fClassic Shock Transmitterwithout over load protection(MSTU) to be designed forFmax 1.5 Fd (EN 15129)Fmax,MSTU 1.5 FdFmax,MSTL 1.1 FdFdFd is design requirementby designer0.1 · FdModern Shock Transmitterwith over load protection(MSTL) to be designed forFmax 1.1 Fd (EN 15129)0.01 · Fd0 10.0010.010.1v0 1.010100In the shock transmitter developedby MAURER, denominated MSTU, bothresistance to the movements due tothermal variations and deformationsconsequent to an earthquake attackhave been minimized, thanks to theadoption of function, special materials,accurate design procedures andproprietary fabrication processes.The MSTU activation or lock-upvelocity v0 is usually individually adaptedin the range from 0.1 to 1.5 mm/s, butfor very large structures can reach thevalue of 5 mm/s.log v (mm /s) Shock Transmitter with Load Limiter (MSTL)The European Norm EN 15129 requires that the reliability factorof shock transmitters on their design force Fd shall be γx 1.5,unless an overload protection system or “load limiter” isincorporated. In this case, the value of the reliability factor canbe reduced to γx 1.1 and shall be applied to the design systemforce F0 specified by the designer. The adoption of MSTLsdecreases the forces acting on the structural members by 26 %.It increases the overall safety of the devices and the structureas it is granted that all devices in serial and parallel arrangement8are equally and simultaneously loaded when affected bysudden service or seismic impacts, this is not the case withclassic STUs. These might be overloaded even with morethan the reliability factor of 1.5 applied onto the design forceFd. Therefore the MSTL application reduces the costs of thestructural members and even the cost of the shock transmitteritself, because an MSTL is more compact, i.e. smaller than anMSTU. The MSTL is always the most economical solution, whileproviding additional technical benefits and reliability.

Hydraulic Coupling and Damping Elements Shock transmitter MSTU/MSTLHP x BPHP x BPLenght of the anchoring is 550 mm,variable amoun t depending ondesign forcesL0L1MSTUMSTLFddispl.L1L0HPBPL1LOHPBP[kN][ 201,8