Seismic Devices. LASTO MSB Seismic Isolators. Titelmasterformat durch Kl. Product summary. Design principle.

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1 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 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 MSB-S MSB-S MSB-S MSB-S MSB-S MSB-S MSB-S MSB-S MSB-S MSB-S MSB-S MSB-S MSB-S MSB-S MSB-S 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 MSB-C MSB-C MSB-C MSB-C MSB-C MSB-C MSB-C MSB-C MSB-C MSB-C MSB-C MSB-C MSB-C MSB-C MSB-C EDC [knm] EDC

3 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 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 D 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 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.

5 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 EN and EN , as well as the European code on anti seismic devices pren William Clayton Building, Wellington, New Zealand (1980) The first building in the world to be seismically isolated with lead-rubber bearings

6 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 Worldwide references Version mageba sa Solistrasse Bülach Switzerland Tel.: Fax: info@mageba.ch bridges linking people worldwide mageba gmbh Fussach, Austria Tel.: Fax: oesterreich@mageba.ch mageba sa Cugy VD, Switzerland Tel.: Fax: suisse@mageba.ch mageba gmbh Uslar, Germany Tel.: Fax: uslar@mageba.ch mageba gmbh Esslingen a.n., Germany Tel.: Fax: stuttgart@mageba.ch mageba Bridge Products (Pvt.) Ltd. Kolkata, India Tel.: to -253 Fax: info@mageba.in mageba Bridge Products Pvt. Ltd. Shanghai, China Tel.: Fax: info@mageba.cn