Urban habitat constructions under catastrophic events. Shear panels for seismic upgrading of new and existing structures

Transcription

1 COST C26 Urban habitat constructions under catastrophic events 1 st Workshop Prague, 30 th -31 st March, 2007 WG2 earthquake resistance Shear panels for seismic upgrading of new and existing structures G. De Matteis, G. Brando PRICOS, University of Chieti/Pescara F. M. Mazzolani, S. Panico, A. Formisano Dept. of Structural Engineering, University of Naples Federico II

2 Stiffened shear plate METAL SHEAR PANELS Stress (MPa) Adopted metals Mild Steel Aluminium Alloy Low Yield Steel Pure Aluminium F Strain (%) F v v Tension field mechanism (elastic buckling) Pure shear mechanism (no-buckling)

3 SHEAR PANELS ARRANGEMENTS AND RELATED TESTING ACTIVITIES Full bay type Partial bay type Bracing type Pillar type

4 ALUMINIUM ALLOY USED FOR SHEAR PANELS Cycles of heat treatment of the aluminium alloy N PHASE TEMPERATURE EXPOSURE TIME BRINNELL INDEX [ C] [hours] [MPa] iniziale ambiente / AW 1050A specimen Material f 0.2 f u e u E a =f u /f 0.2 [N/mm 2 ] [N/mm 2 ] % [N/mm 2 ] [N/mm 2 ] LYS steel Nominal Pure Aluminium (EN-AW 1099A) Nominal Pure Aluminium (EN-AW 1050A) / Employed Pure Aluminium (EN-AW 1050A) Heat Treated Pure Aluminium (EN-AW 1050A) E/f 0.2

5 ALUMINIUM ALLOY USED FOR SHEAR PANELS-Cyclic behaviour 60 BUCKLING BUCKING INHIBITED SPECIMEN PANEL 40 FORCE [kn] DISPLACEMENT [mm] COMPRESSION/TENSILE STRESS [MPa] mm BUCKLING INHIBITED PANEL BUCKLING INHIBITED PANEL mm mm mm mm mm mm mm

6 EXPERIMENTAL CAMPAIGN ON FULL BAY TYPE PURE ALUMINIUM SHEAR PANELS

7 TESTED CONFIGURATIONS OF FULL BAY SHEAR PANELS Panel type F b/t=50 Panel type B b/t=100 Panel type G b/t=50 (=25 in the corners) Panel type H b/t=50 (ribs: UPN50)

8 CYCLIC BEHAVIOUR OF TESTED PANELS shear stress (MPa) shear stress (MPa) PURE ALUMINIUM -30SHEAR PANEL CONFIGURATION -40 TYPE H shear strain (mm/mm) shear stress (MPa) PURE ALUMINIUM SHEAR PANEL CONFIGURATION TYPE F shear strain (mm/mm) time (s) PURE ALUMINIUM SHEAR PANEL CONFIGURATION TYPE G Panel type F shear strain (mm/mm) shear stress (MPa) shear strain (mm/mm) shear stress (MPa) PURE ALUMINIUM SHEAR PANEL CONFIGURATION TYPE B shear strain (mm/mm) time (s) 0 PURE ALUMINIUM SHEAR PANEL CONFIGURATION TYPE H Panel type B shear strain (mm/mm) Panel type G shear strain (mm/mm) time (s) shear strain (mm/mm) shear strain (mm/mm) time (s) Panel type H

9 NUMERICAL SIMULATION OF EXPERIMENTAL TESTS ON ALUMINIUM PANELS Shear panel Type B shear force [kn] experimental data -180 numerical simulation data -220 shear displacement [mm] Shear panel Type F shear force [kn] numerical simulation data -180 experimental data -220 shear displacement [mm]

10 ANALYTICAL INTERPRETATION OF EXPERIMENTAL TESTS E ζ G S eq sec 1 = Δτ Δγ 8 1 ED = 4π E = Δτ Δγ S HARDENING RATIO τ max /τ 02 AW 1050A-Type H

11 ANALYTICAL INTERPRETATION OF EXPERIMENTAL TESTS E ζ G S eq sec 1 = Δτ Δγ 8 1 ED = 4π E = Δτ Δγ S SECANT SHEAR STIFFNESS G sec AW 1050A-Type G

12 ANALYTICAL INTERPRETATION OF EXPERIMENTAL TESTS E ζ G S eq sec 1 = Δτ Δγ 8 1 ED = 4π E = Δτ Δγ S EQUIVALENT VISCOUS DAMPING FACTOR 35% ζ eq AW 1050A-Type H AW 1050A-Type G

13 DIAGONAL TESTING SYSTEM FOR BRACING TYPE SHEAR PANELS

14 GEOMETRICAL CONFIGURATION OF TESTED SHEAR PANELS BTPASP configuration 1 (b/t=100) SHEAR CYCLIC TESTS BY DIAGONAL STRESS BTPASP configuration 2 (b/t=50)

15 EXPERIMENTAL RESULTS FOR BRACING TYPE PANELS

16 ADDITIONAL TESTED CONFIGURATIONS BTPASP configuration 3 (b/t=33) BTPASP configuration 4 (b/t=25)

17 EXPERIMENTAL RESUTS

18 SEISMIC PROTECTION OF EXISTING R.C. BUILDINGS BY METAL SHEAR PANELS ILVA-IDEM (Intelligent DEMolition) RESEARCH PROJECT Coordinator: prof. F.M.Mazzolani - University of Naples Federico II Module n 5 Metal shear panels

19 SEISMIC PROTECTION OF EXISTING R.C. BUILDINGS BY METAL SHEAR PANELS Module n 5 Metal shear panels Steel panels Aluminium panels

20 THE BUILDING UNDER INVESTIGATION Other than the structural degradation due to both age and environmental conditions, the experimental test on SMA braces in the transversal direction determined a further reduction of the module mechanical features Such a situation has been considered in the definition of the numerical model of the sub-structure, which has been used in order to calibrate the structural cyclic experimental behaviour in the longitudinal direction, where seismic retrofitting intervention has been foreseen Structural Reaction The experimental steel consolidation structure test used in the in trasnverse the experimental direction activity Hydraulic jack

21 The experimental test TEST ON THE BARE RC FRAME

22 SEISMIC RETROFITTING METHODOLOGY AND DESIGN OF RC STRUCTURES BY MEANS OF METAL SHEAR PANELS Starting from the knowledge of the contribution which shear panel should provide in terms of both strength and stiffness, its design can be performed by means of the following simplified theoretical relationships: 1 E b t V = f yt blsin 2α K = 2 4 h s Shear panels are realised with two different metallic materials: The definition of materials allows to achieve the shear panels The shear wall has been subdivided into six elements geometrical dimensions : (600x400mm) connected each other and with the frame by STEEL means of M14 bolts having pitch of 50 mm. f y =305 Nmm -2 f u =340 Nmm -2 ε u >30% b b = mm mm d d = mm mm s= s= 1,15 1,15 mm mm PURE ALUMINIUM Being b/d = 0,25 (less than the minimum value (0.8) which guarantees the full activation of tension field), in order to increase such a ratio, two coupled 100 x 4 mm fishplates have been inserted on both sides of the plate f 02 =20 Nmm -2 f u =80 Nmm -2 ε u >30% b b = mm mm d d = mm mm s= s= 55 mm Block tearing failure mechanism mm

23 SEISMIC RETROFITTING METHODOLOGY AND DESIGN OF RC STRUCTURES BY MEANS OF METAL SHEAR PANELS THE EXTERNAL STEEL FRAME

24 SEISMIC RETROFITTING METHODOLOGY AND DESIGN OF RC STRUCTURES BY MEANS OF METAL SHEAR PANELS THE STEEL FRAME RC STRUCTURE CONNECTIONS

25 THE EXPERIMENTAL TESTS ON THE MODULE EQUIPPED WITH METAL SHEAR PANELS MEASUREMENT DEVICES

26 THE EXPERIMENTAL TESTS ON THE MODULE EQUIPPED WITH METAL SHEAR PANELS CYCLIC TEST ON THE RC MODULE STEEL PANELS COMPOSED STRUCTURE - quasi-static conditions; - increase of 20 kn for each cycle up to the last one, where the increment was of 60 kn; - symmetric load condition up to 200 kn (hence the compression load has been increased up to 300 kn only). From the the cyclic test Creation test it Creation itisisapparent of Buckling of Buckling buckling buckling phenomena that phenomena wave that wave Very the in in the the appear loading appear Tension Tension Full Full some some phases plastic field plastic field subpanels one panels interest panels develops behaviour develops stiffness in behaviour in of the of the all plates, Very pronunced pronunced buckling buckling sub- waves waves which which all are plates, are sub- subpanels not notcoincident upper with withthe the unloading phases upper sub-panel sub-panel one due due to interest all to the the formation all panel panel but but fields fields the the with with (folding permanent of (folding of foldings permanent isdisappears) disappears) always always deformations deformations present in present in the the upper subpanel which make the the system less lessrigid rigidand delay the the activation of of the the tension field sub- field

27 THE EXPERIMENTAL TESTS ON THE MODULE EQUIPPED WITH METAL SHEAR PANELS CYCLIC TEST ON THE RC MODULE ALUMINIUM PANELS COMPOSED STRUCTURE - quasi-static conditions; - increase of 10 kn for each cycle up to the last one, where the increment was of 60 kn; - symmetric load condition up to 200 kn (hence the compression load has been increased up to 300 kn only). As Asin in the the experimental test test on on the the structure retrofitted with withsteel panels, also alsoin in this this case case the the presence of of buckling All All sub-panels sub-panels waves show show determine, significant significant buckling buckling even waves. evenifwaves. ifin in less less No pronunced way, No buckling buckling phenomena Pronunced Pronunced way, a reduction phenomena Pronunced instability instability Also Also in phenomena phenomena the the end end ones ones in in tension the tension the field field mechanism Pronunced foldings mechanism panel of fileds. of the foldings Buckling the Foldings system Buckling the the end are end waves stiffness still waves sub- sub- in visible in the develops the panel. in the panel. Foldings Foldings panel fileds. panels panels Foldings increase are still visible develops the end end sub-panels increase in in the the terminal terminal panel panel fields fields sub-panels

28 THE EXPERIMENTAL TESTS ON THE MODULE EQUIPPED WITH METAL SHEAR PANELS CYCLIC TEST ON THE RC MODULE ALUMINIUM PANELS No No buckling buckling phenomena phenomena Pronunced Pronunced foldings foldings in in the the end end sub-panels sub-panels Pronunced Pronunced instability instability phenomena phenomena in in the the panel panel fields fields All All sub-panels sub-panels show show significant significant buckling buckling waves waves

29 COMPARISON BETWEEN EXPERIMENTAL RESULTS Shear (kn) RC structure RC structure + steel panels RC structure + aluminium panels Displacement (mm)

30 CONCLUSIONS 1. The use of metal shear panels for the seismic protection of new and existing buildings has been investigated; 2. Experimental tests on full bay, bracing type and partial bay type pure aluminium shear panels have been carried out; 3. The obtained results emphasize that shear metals panels actually represent a very attractive strategy to reduce the seismic vulnerability of new (steel) and exiting (RC) framed structures subjected to large earthquakes.