www.mageba.ch Seismic Devices Seismic Isolators Titelmasterformat durch Kl Product summary The Seismic Isolator is designed to isolate the structure from horizontal ground movements due to seismic events. The bearing consists of alternating horizontal layers of rubber and reinforcing steel shims. It is normally fabricated with the rubber vulcanised directly to the top and bottom anchoring plates. The bearing however can also be manufactured with a vulcanised top and bottom plate which then is bolted to additional anchor plates, allowing easier replacement of the bearing. The is generally available in natural rubber (NR) with a central lead plug making it a lead rubber bearing (type LRB). Alternatively, the bearing can also be designed with a high damping rubber (HDRB), with a damping value between 5 and 15 %. Such bearings do not form part of this prospectus but are available upon request. Internal steel plates + Rubber layers Lead Rubber Bearing Lead core Rubber Design principle Shear Force (KN) Displacement (mm) Force-displacement Hysteresis Loop Seismic Isolators work on the principle of base isolation and limit the energy transferred from the ground to the structure in order to protect it. The rubber/steel laminated bearing is designed to carry the weight of the structure and make the post-yield elasticity available. The rubber provide the isolation and the recentering, while the lead core deforms plastically under shear deformations. Its size can be selected to produce the required amount of damping. The force displacement hysteresis loop is a typical characteristic of the lead rubber bearing.
2 Product Dimensions and Characteristics Lead Rubber Bearing a a N H H B Rubber Lead Steel Typical cross-section Force Force Q2 H 2 K 1 K1 EDC = Shaded Area Q1 H 1 EDC = Shaded Area K K K2 2 eff vdbe dmax Displacement Displacement Force-displacement Hysteresis Loop a : square rubber bearing width d : circular rubber bearing diameter H B : total bearing height H 1, H 2 : specific horizontal load of the hysteresis loop N max : max. vertical load v dmax : resultant of the horizontal displacement (maximum for given displacement) v u : ultimate horizontal (failure) displacement K 1, K 2 : specific horizontal compressive deflection of the bearing from the hysteresis loop K eff : effective horizontal compressive deflection of the bearing from the hysteresis loop EDC : energy dissipated per cycle Square bearings with lead core Type & size Vertical Load N max Circular bearings with lead core Horizontal Load Displacement Horizontal Stiffness H 1 H 2 v dmax v u K 2 K 1 K eff Dimension a = b The Seismic Isolators comes in square (S), rectangular (R) or circular (C) and the type names indicate shape and lateral size of the bearing. For example, MSB-S-600 is a square bearing of 600mm, MSB-R-400x700 is a rectangular bearing. The tables shows only examples for square and circular lead rubber bearings. Other sizes are available on request. The minimum and maximum pressure as well as maximum displacement are recommended values only. mageba designs its bearings according to the code that the costumer needs to follow. Bearing Height H B MSB-S-500 2 750 138 275 250 375 550 3 850 1 100 500 294 115 MSB-S-550 3 330 167 333 275 413 605 4 238 1 211 550 310 153 MSB-S-600 3 950 198 395 300 450 658 4 608 1 317 600 329 198 MSB-S-650 4 650 233 465 325 488 715 5 008 1 431 650 348 252 MSB-S-700 5 400 270 540 350 525 771 5 400 1 543 700 367 315 MSB-S-750 6 200 310 620 375 563 827 5 787 1 653 750 386 388 MSB-S-800 7 050 353 705 400 600 881 6 169 1 763 800 405 470 MSB-S-850 7 950 398 795 425 638 935 6 547 1 871 850 424 563 MSB-S-900 8 900 445 890 450 675 989 6 922 1 978 900 444 668 MSB-S-950 9 900 495 990 467 700 1 061 7 425 2 121 950 458 770 MSB-S-1000 11 000 550 1 100 467 700 1 179 8 250 2 357 1 000 458 856 MSB-S-1050 12 100 605 1 210 467 700 1 296 9 075 2 593 1 050 458 941 MSB-S-1100 13 300 665 1 330 467 700 1 425 9 975 2 850 1 100 458 1 034 MSB-S-1150 14 500 725 1 450 467 700 1 554 10 875 3 107 1 150 458 1 128 MSB-S-1200 15 900 795 1 590 467 700 1 704 11 925 3 407 1 200 458 1 237 MSB-S-1300 18 600 930 1 860 467 700 1 993 13 950 3 986 1 300 458 1 447 Type & size Vertical Load N max Horizontal Load Displacement Horizontal Stiffness H 1 H 2 v dmax v u K 2 K 1 K eff Dimension (diameter) d Bearing Height H B [knm] MSB-C-500 2 150 108 215 233 350 461 3 225 921 500 278 84 MSB-C-550 2 620 131 262 257 385 510 3 573 1 021 550 296 112 MSB-C-600 3 100 155 310 280 420 554 3 875 1 107 600 313 145 MSB-C-650 3 650 183 365 303 455 602 4 212 1 203 650 331 185 MSB-C-700 4 250 213 425 327 490 651 4 554 1301 700 349 231 MSB-C-750 4 850 243 485 350 525 693 4 850 1 386 750 367 283 MSB-C-800 5 550 278 555 373 560 743 5 203 1 487 800 384 345 MSB-C-850 6 250 313 625 397 595 788 5 515 1 576 850 402 413 MSB-C-900 7 000 350 700 420 630 833 5 833 1 667 900 420 490 MSB-C-950 7 800 390 780 443 665 880 6 158 1 759 950 439 576 MSB-C-1000 8 600 430 860 467 700 921 6 450 1 843 1 000 458 669 MSB-C-1050 9 500 475 950 467 700 1 018 7 125 2 036 1 050 458 739 MSB-C-1100 10 450 523 1 045 467 700 1 120 7 838 2 239 1 100 458 813 MSB-C-1150 11 400 570 1 140 467 700 1 221 8 550 2 443 1 150 458 887 MSB-C-1200 12 400 620 1 240 467 700 1 329 9 300 2 657 1 200 458 964 MSB-C-1300 14 600 730 1 460 467 700 1 564 10 950 3 129 1 300 458 1 136 EDC [knm] EDC
Technical Parameters 3 Effective Secant Stiffness The effective secant stiffness is an important parameter as it determines the apparent resonant period of a seismically isolated structure. Figure 1 shows the test results for an at different displacement amplitudes, and the different symbols indicate the effective stiffness of the first and third loading cycles. EFFECTIVE STIFFNESS First load cycle Third load cycle Testing of the finger joint DISPLACEMENT Fig. 1: Effective Secant stiffness of Damping Ratio [%] First load cycle Third load cycle Displacement Fig. 2: Hysteresis Loop Area of Hysteresis Loop Area These values normally vary less than 5% and the solid line is from the prediction equations. The Hysteresis loop area of an is the energy absorbed by the bearing during a loading cycle and the loop area determines the equivalent damping ratio of an isolation structure contributed by the MSBs. Figure 2 shows the test results for a particular at a number of displacement amplitudes, with the different symbols are the loop area for the first and third loading cycles. These values differ usually less than 10% and the solid line is from the prediction equation for the first loading cycle. Displacement - Damping Ratio Figure 3 shows the test results for an at different displacement amplitudes, and the different symbols indicate the effective stiffness of the first and third loading cycles. These values normally vary less than 10% and the solid line shows the predicted average value. For most types of LRB, the damping ratio can exceed 20% at a large design displacement. Damping ratio [%] First load cycle Third load cycle Displacement Fig. 3: Equivalent Damping Ratio of Number of loading cycles - Damping Ratio DAMPING RATIO [%] No. of load cycles [-] Fig. 4: Equivalent Damping Ratio of The equivalent damping ratios of a is very stable as shown in Figure 4 which presents the testing results of equivalent damping ratios for 10 loading cycles. For all of high damping rubber, damping ratios tend to decrease after the first loading cycle. For all of the, the maximum difference in equivalent damping ratios is usually within 10% for a reasonably large number of loading cycles.
4 Technical Description Anchoring system Usually all are equipped with suitable anchor plates to facilitate anchoring to lower and upper structures. Alternatively, these bearings can also be supplied for connection to steel structures. Materials with anchor plates The following materials are used for the production of mageba seismic bearings: Shim plates and top and bottom plates are made from rolled carbon steel conforming to ASTM A36 or A570 The purity of lead is established by chemical analysis and will confirm a minimum of 99.9% purity of the lead. Natural rubber, Type NR, Grade 3 per ASTM D4014-81. Corrosion protection Steel components exposed to the elements are corrosion protected. mageba adjusts the corrosion protection to suit exposure conditions or customer requirements. Standard corrosion protection is as follows: Sandblasting SA 2.5 Inorganic zinc primer (70 85 μm) Two top coatings with approved pu paint at 100-125 μm Bearing tested in a testrig Test of a lead rubber bearing Full-scale and individual tests Full-scale testing can be carried out, if required. Mageba performs its tests at a recognised independent test institute. Commonly used tests are: Tensile stress measurement in accordance with ASTM D412. Tensile strength and ultimate elongation of elastomeric in accordance with ASTM D412. Rubber-to-Metall Bond strength in accordance with ASTM D429. Durometer hardness in accordance with ASTM D224 Heat resistance in accordance with ASTM D573. Compression set in accordance with ASTM D395 Method B. Brittleness in accordance with ASTM D2137 Method A. Low temperature properties in accordance with ASTM D1229 and ASTM D224 Ozon resistance in accordance with ASTM D518 Method A and ASTM D1149. Cyclic shear tests in accordance with ASTM D4014. Inspection of an installed bearing Inspection and maintenance Seismic Isolators are maintenance free. The condition and position of the bearings shall be inspected at regular intervals. Upon request, the mageba inspection team can carry out such inspections and summarize the results in a detailed report.
Quotations and orders 5 Your enquiry When requesting a quotation, please provide the best design criteria available, to enable us to give you the best possible quotation. We process quotes immediately and make them available as soon as possible. Our quotation Staff of our technical department We can send you an indicative offer on the basis of classification and number of bearings. For a binding offer we need the following information: Total design displacement (seismic, thermal, irreversible movements) Total maximum displacement Horizontal stiffness (Elastomer shear modulus) Compression stiffness Design vertical load in static condition Maximum vertical load in seismic condition Minimum vertical load in seismic condition Equivalent viscous damping General data on the structure (concrete or steel bridge, fixing details of the bridge bearings, etc.) Bearing design code (AASHTO / DIN / EN / or other) Placing of orders In addition to the information already supplied, the following documents are also necessary when placing an order: Layout drawing of the structure Work begins once the customer has approved and returned the documents. Delivery time is kept to a minimum thanks to an efficient order processing system and modern manufacturing methods. The most important features of the Seismic Isolators mageba designs and produces Seismic Isolators Seismic Isolators are approved in many countries worldwide Quality control of design and production is in accordance with ISO 9001:2000 External quality control conducted by an independent building supervision institute Seismic Isolators comply to the requirements of international standards as DIN 18800, European codes on construction EN1998-1 and EN 1998-2, as well as the European code on anti seismic devices pren15129. William Clayton Building, Wellington, New Zealand (1980) The first building in the world to be seismically isolated with lead-rubber bearings
6 Products and references Bridge Bearings - Pot Bearings - Elastomeric Bearings - Earthquake Bearings - Spherical Bearings - Incremental Launch Bearings - Special Bearings - Rocker Bearings Expansion Joints - Single Gap Joints - Modular Expansion Joints - Sliding Finger Joints - Cantilever Finger Joints - Matt Joints - Railway Joints - Architectural Joints Seismic Protection - Seismic Rubber Bearing (LRB, HDRB) - Preloaded Spring dampers - Shock Transmission units - Viscous damper - Spring Dampers Services - Inspections - Tests - Installations - Refurbishments - Cleaning - Remote monitoring More information on mageba and its products can be found on www.mageba.ch. Worldwide references Version 2008.10 mageba sa Solistrasse 68 8180 Bülach Switzerland Tel.: +41-44-872 40 50 Fax: +41-44-872 40 59 info@mageba.ch bridges linking people worldwide mageba gmbh Fussach, Austria Tel.: +43-5578-75593 Fax: +43-5578-73348 oesterreich@mageba.ch mageba sa Cugy VD, Switzerland Tel.: +41-21-731-0710 Fax: +41-21-731-0711 suisse@mageba.ch mageba gmbh Uslar, Germany Tel.: +49-5571-9256-0 Fax: +49-5571-9256-56 uslar@mageba.ch mageba gmbh Esslingen a.n., Germany Tel.: +49-711-758844-0 Fax: +49-711-758844-56 stuttgart@mageba.ch mageba Bridge Products (Pvt.) Ltd. Kolkata, India Tel.: +91-33-22900250 to -253 Fax: +91-33-22900254 info@mageba.in mageba Bridge Products Pvt. Ltd. Shanghai, China Tel.: +86-21-5740 7635 Fax: +86-21-5740 7636 info@mageba.cn