Experimental investigation of vertically reinforced masonry walls

Transcription

1 Experimental investigation of vertically reinforced masonry walls Author: Anita Fódi Supervisor: István Bódi, Associate Professor Faculty of Civil Engineering Department of Structural Engineering Fourth International PhD Symposium in Engineering

2 Contents Short history of reinforced masonry Why exactly shear investigation? Common failure of masonry The possible type of bond Summary and further plans

3 History of reinforced masonry 1825 Marc Isambard Brunel: Blackwall Tunnel under the Thames flower stands of the Park Güell

4 The Eurocode 6 in Hungary Mechanical properties + f yd Compressive strength Shear strength Flexural strength Anchorage strength Unit Mortar Initial shear strength Compressive stress Unit Mortar Steel Mortar f k =Kf b α f m β f vk =f vk0 +0,4 σ d f xk1 ; f xk2 f b0k

5 Acting loads and failure modes Vertical Horizontal Lateral N M Ed =αw Ed l 2 Ed N Rd = Φtf d V N Edc N Rdc = βa b f Ed V Rd = f vd tl c d M Ed M Rd = f xd Z UNREINFORCED Bending, axial loading or both: Shear: VERTICAL REINFORCEMENT 1.) Horizontal load: V Rd1 = f vd tl M Ed M Rd =A s f yd z 0,4f d bd 2 V Ed V Rd1 + V Rd2 f vd =min(inf.;mas.) V Rd2 =0,9A sw f yd (V Rd1 +V Rd2 )/(tl) 2 N/mm 2 REINFORCED 2.) Shear load: V Ed V Rd1 + V Rd2 f vd =min(inf.;mas.) V Rd1 = f vd bd V Rd2 =0,9dA sw f yd /s V Rd1 +V Rd2 0,25 f d bd

6 Common failure of masonry Rocking of piers Crushing Uplifting of masonry Failure owning to earthquake X-Cracking of masonry piers X-cracking due to main stresses

7 The resolution Roof band Bending of piers (instead of X-cracking) Plinth band Vertical steel bars anchored in foundation and roof band

8 Shear mechanism V n =V m +V s F h1 Cracking V V n : nominal shear strength d1 F V h2 s : horizontal reinforcement V d2 V m : residual strength of masonry Fv1 v1 F h3 V d3 F v2 V V a c : shear resistance in the compression toe F h4 V V a : aggregate interlock force d4 V m =V c +V a +V d V d : dowel forces of flexural reinforcement Horizontal and vertical reinforcement are needed for the adequate shear capacity! F v3 F h5 V d5 F v4 V c

9 Horizontal reinforcement

10 Questions in connection with shear: EC6 adjudges that the effect of shear deformations on the stiffness can be neglected only if the wall is higher then twice its length EC6 deals only with concrete infill EC6 applies mostly to horizontal reinforcement EC6 doesn't contain: what happens if vertical reinforcement is placed in mortar pockets (not in hollow blocks) Shear strength of mortar Adhesion between steel-mortar-brick Problem of ductility Not conventional bonding of bricks

11 Reinforced pocket type wall 25 1,5 12 1,5 25 1,5 12 1,5 25 1,5 12 1,5 25 1, ,5 14,

12 Reinforced solid wall Conventional Hungarian solid brick 250x120x65 185, ,75 46,75 46,75 172

13 The schematic of the test setup 20t t 56 HEA200 U300 40t 120 HEA200 U

14 Further plans Wall without reinforcement Wall with vertical reinforcement Wall with horizontal reinforcement Wall with horizontal and vertical reinforcement

15 Summary and conclusions In the literature Experiments that use concrete hollow masonry bricks Current research Consist of clay solid bricks Tests that possess of concrete grouting Are built with mortar grouting EC6 doesn't contain direction for: the size of pockets Can investigate the size of the pocket EC6 doesnt contain direction for: the amount of vertical steel that can be taken into account during shear Would investigate the effect of vertical reinforcement V Ed V Rd1 + V Rd2 V Rd1 = f vd tl f vd =min(inf.;mas.) V Rd2 =0,9A sw f yd?????

16 Thank you for your kind attention!