APPLICATION OF ANTI-SEISMIC SYSTEMS TO CULTURAL HERITAGE BUILDINGS

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Maximilian Boyd
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1 Seminario annuale GLIS L ADEGUAMENTO DEGLI EDIFICI CON I SISTEMI ANTISISMICI Aeroporto d Abruzzo, Pescara e San Giovanni Teatino (CH) 18 Ottobre 2013 APPLICATION OF ANTI-SEISMIC SYSTEMS TO CULTURAL HERITAGE BUILDINGS Paolo Clemente

Giovanni Teatino (CH) 18 Ottobre 2013 APPLICATION OF

2 HISTORICAL BUILDINGS Were designed without accounting for the seismic actions Are vulnerable even to moderate events Are often characterized by: an irregular shape, both in plan and in elevation vertical connections between the walls not effective in-plane flexibility of floor slabs, shallow foundations. Seismic rehabilitation is quite delicate: The safety factor should be high enough due to the daily presence of tourists The original monumental characteristics, identity and historical value should be preserved

in-plane flexibility of floor slabs, shallow foundations.

3 TRADITIONAL TECHNIQUES SEISMIC ISOLATION Traditional techniques are not suitable for the seismic rehabilitation of cultural heritage buildings Are based on the increasing of strength and ductility Are often not reversible Make use of materials different and incompatible with the original ones Determine changes in the original structural conception Under earthquakes of high intensity, can just guarantee against the collapse Cannot avoid heavy damages to structural and non-structural elements New anti-seismic technologies are suitable for the rehabilitation of historical structures Aims to reduce seismic actions, thus avoiding significant damages to the structure and its contents even under strong earthquakes Presents very low interference with the structure itself

intensity, can just guarantee against the collapse Cannot avoid heavy damages to structural and non-structural elements New anti-seismic technologies are suitable for the rehabilitation of

4 RETROFIT OF CU.HE. BUILDINGS BY B.I. Salt Lake City & County Bldg. (1894) retrofit in 1989, 447 LRBs & LDRBs, cost=4.4 MUS$ Wellington Parliament, built in 1921 (retrofit with LRBs in ) Asian Art Museum, San Francisco (HDRBs) National Western Art Museum (Le Corbusier), Tokyo Retrofit with sub-foundation (1999) 1 st retrofit of museums with I.S.)

4 MUS$ Wellington Parliament, built in 1921 (retrofit with LRBs in 1992-93) Asian Art

5 AKROTIRI EXCAVATIONS, SANTORINI ISLAND, GREECE Spatial structure (11,800 m 2 ) supported by 94 steel columns on 94 LRBs (2003)

6 SEISMIC ISOLATION OF SINGLE MASTERPIECES Germanicus Emperor, Perugia Bronzes of Riace Dancing Satyr of Mazara del Vallo Capestrano Warrior Japanese sliding table with sphere recirculation isolators (G8 Summit, 2009, in L Aquila) Copies of Scylla and Neptune, Messina SMADs + SDs Statue in China

Japanese sliding table with sphere recirculation isolators (G8 Summit,

7 SMAD AND STU AT S. FRANCIS IN ASSISI (1999) 34 STUs 47 SMADs

8 S.GIORGIO CHURCH BELL TOWER IN TRIGNANO Damaged by the 1996 Reggio Emilia earthquake

9 DAMPERS Santa Maria di Collemaggio in L Aquila: EP steel braces on the roof of Siena Dome: recentring VDs to hinder the overturning of the façade

10 S e (g) S De (m) Seminario annuale GLIS L ADEGUAMENTO DEGLI EDIFICI CON I SISTEMI ANTISISMICI PRELIMINARY DESIGN: CHOICE OF T is ELASTIC SPECTRA Isolation system - SLC Superstructure - SLV Isolation system: SLC Superstructure: SLV (q=1.5) Foundations: SLV (q=1) * S e T (s) T is S e * = corresponds to the seismic action that the restored building will be able to support in the elastic range T is = corresponds to S e * in the SLV spectrum, which should also guarantee a suitable decoupling between the motion of the building and the motion of the soil a displacement compatible with the gap T is T bf

5) Foundations: SLV (q=1) * S e 0.0 0 1 2 3 4 T (s) T is 0.1 0.

11 PRELIMINARY DESIGN: DEVICE STIFFNESS Model: rigid box with horizontal elastic springs 3 DOF system (2 translations + 1 rotation) Goal: the first 2 modes of vibration should be translational along the 2 main directions M = total mass of the superstructure T is = fundamental period of the isolated building T 2 is K M esi K esi = horizontal stiffness of the isolation systems HDRB: stiffness of the single isolator K e K esi n T is g R d CSS: radius of the devices

of the superstructure T is = fundamental period of the isolated building T 2 is K M esi K esi = horizontal stiffness

12 CITY HALL IN SAN FRANCISCO Destroid by the earthquake of 1906 Recostructed in 1912 Damaged during the earthquake of Loma Prieta in 1989 Retrofit, 2000 (530 LRB, 62 SD)

13 SCHOOL BUILDING IN VANADZOR, ARMENIA Masonry building 4 levels (55 years) Retrofit, by means of Medium Damping Rubber Bearings (MDNB), 2002 (courtesy by prof. M. Melkumyian)

14 ST. CATHOGHIKEH (YEREVAN, ARMENIA)

15 BASE ISOLATION AT THE FOUNDATION LEVEL Insertion of the isolation devices: In the walls of the ground level of the building just under the foundations This solution: requires traditional work is not very expensive But presents the disadvantages of requires the modification of the foundations is not reversible It is not always applicable in practice for historical constructions

work is not very expensive But presents the disadvantages of requires the modification of the

16 S. I. STRUCTURE FOR EXISTING BUILDINGS isolated platform under the foundations of the building, without touching the building itself Gap Earth Rigid connection External wall Internal wall Isolators Inserted after removal of the special elements of the pipes Upper cilindrical sector Lower cilindrical sector Pipes inserted by means of auger boring or micro-tunnelling technique; D 2 m

Isolators Inserted after removal of the special elements of the pipes Upper cilindrical sector

17 SISEB: INSERTION OF THE PIPES Excavation of a trench at one side of the building Insertion of horizontal pipes by means of auger boring or microtunnelling technique (no dig techniques - diameter of pipes 2 m, in order to allow the inspection)

of auger boring or microtunnelling technique (no dig

18 SISEB: SPECIAL PIPES Have a particular shape Are composed of two portions (lower and upper sectors), which are connected by means of removable elements: Red elements: where the isolators will be inserted Grey elements, just to remove

connected by means of removable elements: Red elements:

19 SISEB: ISOLATION DEVICES Removal of the connection elements (red) placed in correspondence of the isolation devices Joining each pipe with the two adjacent ones (r. c. elements) Positioning of the isolation devices Joining of the upper adjacent sectors at the isolator places Removal of the other connection elements (grey), so the lower and upper sectors are definitely separated

elements) Positioning of the isolation devices Joining of the upper adjacent sectors at the

20 SISEB: VERTICAL WALLS Vertical walls along the four sides Rigid connection between the building and the isolation system, by means of a concrete slab or other

21 STATIC AND DYNAMIC ISSUES Vibrations induced at the surface level Literature is not very ample and often not strictly pertinent Analogue experiences (large tunnelling works or vertical boreholes) suggest that minor threats should be expected from induced vibrations Theoretical and experimental deeper studies are needed. Soil settlement More serious problems can arise by settlements

22 CASE STUDY: PALAZZO MARGHERITA (PM) dynamic characterization conventional improvement intervention, which allows the structure to be able to support minimum seismic actions (0.05g) base isolation system

23 PALAZZO MARGHERITA: GENERAL VIEW

24 PALAZZO MARGHERITA: PLANT Nord Size 58 x 40 m Yard 27 x 12 m Heigth 19 m

25 PALAZZO MARGHERITA: DAMAGES Deck collapsed Tower Stairs Overturnig of external wall Shear collapse

26 MODELLING FE 2-D model in Diana 2 environment (to analyze a perturbation of limited width, which is due to the foundation and to the micro-tunnels) Vertical edges of the model far enough from the perturbed zone (to minimize their influence; nodes of those edges were restrained by means of spring and dampers able to cut-off the wave reflection) Soil as a layered continuum indefinitely extended, supported by the bedrock at 17 m depth (layer thickness = 1.0 m; G din coherent with measured wave propagation velocities; mass density = 2090 kg/m 3 ) Eight node quadrangular elements, plane deformation Restraining conditions: vertical displ. inhibited at the lower horizontal edge horizontal displ. inhibited at the lateral vertical edges

27 SETTLEMENT EVALUATION Settlement (pipe insertion, originated by a stress release process) = Settlement (building weight + pipe insertion) Settlement (building weight) Stress release during micro-tunnelling: by the conventional hole-boundary force reduction approach known as β-value method or convergenceconfinement method (stress-release factor = 0 1) Analyses are based on the decrement of a fictitious internal pressure at the boundary of the holes in agreement with the β-value method Simply supporting elastic restrains are distributed along the hole boundaries, with operating direction orthogonal to them Stress release is simulated by modifying the stiffness of the elastic supports (null stiffness of the elastic support gives =1)

the two most external ones and all the other from the external pipes to the centre Easier to apply, Effect on soil adaptation is not so smooth and regular Settlement = 6.

28 =0.4 and H/D =3.5 Seminario annuale GLIS L ADEGUAMENTO DEGLI EDIFICI CON I SISTEMI ANTISISMICI CONSTRUCTION STRATEGIES (H = depth of the pipe axis, D = pipe diameter) Strategy 1: one central pipe first, then the two most external ones and all the other from the external pipes to the centre Easier to apply, Effect on soil adaptation is not so smooth and regular Settlement = 6.8 mm Strategy 2: one central pipe first, then the two most external ones; other pipes are then inserted in intermediate positions, regularly spaced, filling gradually the layer More regular advancement Settlement = 5.6 mm Larger H/D ratio: reduces the problem but increases the cost of the trenches Technologies to contrast the settlements exist and are consolidated but, push the cost up

29 CONCLUSIONS New isolation system for the seismic retrofit of existing buildings, based on the realization of a isolated platform under the building foundation The building and its architectural aspect are not changed and so are the underground levels Single buildings but also for complex structure, typical of Italian historical centers Realization of tunnels for pedestrian or vehicles Seismic retrofit of existing chemical and power production plants, including the nuclear ones, in which separate buildings or components are connected by complex lifelines, pipes and other links

Seismic Isolation Retrofitting of Japanese Wooden Buildings

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