Masonry Research. Seminar at University of Minho, Portugal

Transcription

1 Masonry Research Seminar at University o Minho, Portugal Presenter: Dr. Yuri Z. Totoev Centre or Inrastructure Perormance an Reliability The University o Newcastle, Australia Seminar topics Bricks with built-in passive solar eiciency: evelopment an testing o their heat transer properties. Empirical reistribution proceure to improve accuracy o linear elastic analysis o shear walls in loa-bearing masonry..

2 Bricks with built-in passive solar eiciency: evelopment an testing o their heat transer properties INTRODUCTION Builings consume between 40 an 60% o all energy use in most evelope economies an an increasing proportion in many eveloping an emerging economies what is not in oubt is that our current epenency on carbon base ossil uels or proviing comort an amenity in builings cannot be sustaine an that alternative strategies require to be explore, esigne, implemente, teste an emonstrate in the immeiate years ahea. At the heart o this is the nee to both exten an improve our knowlege o the processes o energy exchange in builings whether they be high tech commercial builings or the simpler resiential habitats that surroun them. Unerwoo, C.P. & Yik, F.W.H. 2004, Moeling methos or energy in builings, Blackwell Publishing Lt., Melbourne.

3 Builing energy use A stuy by the Australian Greenhouse Oice [AGO, 1999] inicate that by 2010 househol energy eman coul be 160% o 1990 level. Approximately 40% o househol energy use is or space heating an cooling. Resiential energy use accounts or approximately 10% o total energy use. This means that resiential space heating an cooling accounts or approximately 4% o total energy use in the country. Basics o passive energy eicient esign Builing orientation; Builing plan; Winow arrangement; Insulation techniques; Airlow patterns; Energy capture an release rom the builing materials.

4 Key principles o passive solar esign Summer sun is exclue Insulate roo space Brick partition walls (thermal mass) Winow opening Maximum penetration is achieve or Winter sun Concrete loor slab (thermal mass) BRICK WITH BUILT-IN PASSIVE SOLAR EFFICIENCY (BIPSE BRICK) External ace

5 Principles o built-in passive solar eiciency (or Syney latitue) Brick Mortar Shaow Absorbe heat Absorbe heat Summer sun Relecte Winter sun Computer simulation o passive shaing on the northern wall at miay or Syney: a). in summer; b). in winter.

6 MECHANISMS OF HEAT TRANSFER Raiation heating the external surace by solar raiation; Conuction ue to the temperature ierential between external an internal suraces; Convection cooling o the external surace by win. COMPARISON OF THERMAL PERFORMANCE OF CONVENTIONAL AND BIPSE BRICKS Test specimens: Conventional brick with lat external ace; BIPSE brick with 50º inclination o the upper ace o ribs; BIPSE brick with 60º inclination o the upper ace o ribs; BIPSE brick with 70º inclination o the upper ace o ribs.

7 Testing rig Heat source with ajustable angle Perimeter insulation Thermo sensors Constant temperature container Heat lux sencors Brick specimens Summary o the heat absorption test results 250 BIPSE brick BIPSE brick 60 Heat Flux (W/m2 2) BIPSE brick 70 Conventional brick Angle o external heat raiation ( o C)

8 Summary o the heat absorption test results approximately 50W more heat energy is absorbe in winter through 1m 2 o wall; approximately 15W less heat energy is absorbe in summer through 1m 2 o wall; assuming the wall o 20m 2, the average winter exposure o 4 hours, an the average summer exposure o 5 hours, the net aily results are +4kWh in winter an +1.5kWh in summer ( + or esirable eect). Summary o the heat conuction test results ) Heat Flux (W/m t BIPSE Brick 50 heat lux Conventional brick heat lux Room emperature Temperature ( o C) Water temperature

9 Summary o the heat conuction test results approximately 10 W/m 2 is lost when it is 5 o C coler outsie; approximately 4 W/m 2 is gaine when it is 5 o C hotter outsie; in summer at Newcastle, Australia average maximum air temperature is ~30 o C; average internal comort air temperature is ~25 o C; average minimum air temperature is ~20 o C; assuming the wall o 20m 2, the net summer aily eects are -1kWh uring the ay an +2.5kWh uring the night ( - or unesirable ); in winter at Newcastle, Australia average internal comort air temperature is ~22 o C; average maximum air temperature is ~20 o C; average minimum air temperature is ~10 o C; assuming the wall o 20m2, the net winter aily eect is -6.5kWh. CONCLUSION A new brick with built-in passive solar eiciency (BIPSE brick) was esigne at the University o Newcastle, Australia. The external ace o this brick is not lat as in traitional brick but has horizontal ribs esigne to increase the brick surace expose to solar raiation in winter an reuce summer exposure. BIPSE bricks can be mae with minimal implications or the manuacturing inustry an o not require any special bricklaying techniques. Apart rom the improve solar eiciency BIPSE bricks have some aitional architectural beneits: shaes, texture, colour eects, contemporary appearance etc. The experimental set up was evelope to perorm the heat conuction an the heat absorption tests an to compare thermal perormance o traitional an BIPSE bricks. In this test the heat lux though the internal ace o brick is was measure at ierent incient angles o the heat raiation on the external sie o prisms or at ierent temperatures o external an internal surace o brick.

10 CONCLUSION (cont.) A series o heat absorption an heat conuction tests were perorme on conventional an BIPSE bricks with ierent angles o inclination o the upper ace o ribs. In these tests BIPSE bricks emonstrate better heat absorption properties to the conventional brick at both ens o the heat raiation angle range. They absorbe more heat at low incient angles o the heat raiation an less heat at high angles o the heat raiation. From these results it is possible to conclue that BIPSE bricks can potentially absorb up to 40% more solar energy in winter an up to 60% less solar energy in summer in comparison to traitional bricks. Comparison o the heat absorption results an the heat conuction test results reveale that the net eect in coler environment coul be much smaller than observe in heat absorption tests. Empirical reistribution proceure to improve accuracy o linear elastic analysis o shear walls in loa-bearing masonry Pero Sing-Sang & Arian Page

11 LOADBEARING MASONRY CONSTRUCTION Concrete slabs Masonry walls Builings are compose o masonry walls an concrete slabs; Slip joints are locate between walls an loor slabs; Lateral loa path inclues slip joints. There is a potential or slip in the joints an reistribution o loas. masonry wall slip joint concrete slab slip joint masonry wall EARTHQUAKE HAZARD

12 CURRENT DESIGN PROCEDURES CURRENT DESIGN PROCEDURES Governe by Australian Stanars AS (2007) an AS3700 (2001); Practical esigns are usually base on the equivalent static analysis; Shear loas are etermine accoring to wall arrangement an their elastic stiness; Potential slip in the joints is not consiere. DISADVANTAGES Too simplistic or an earthquake or win esign; May consequently lea to unrealistic shear loa preictions resulting in either uneconomical or unsae esign.

13 MORE ACCURATE DESIGN PROCEDURE Base on the response history ynamic analysis; Masonry consiere as a nonlinear an anisotropic material exhibiting sotening behaviour, an slip in the slip joints; Nonlinear eects may cause a reuction in the wall stiness an a reistribution o the shear loas between walls; DISADVANTAGES (or practical esigners) Most esigners have limite access to nonlinear esign tools; Limite computer resources; Limite experience in using complex esign methos an assessing accuracy o numerical results. A COMPROMISE EMPIRICAL REDISTRIBUTION PROCEDURE It uses results o the stanar linear elastic analysis; It takes into account the level o the esign compressive stress on slip joints an the potential o the joint to slip; It oes not require any aitional inormation about a loa-bearing masonry builing apart rom the average overestimation an unerestimation o shear orces by the traitional methos available in technical literature. DISADVANTAGES (limitations) It is evelope to be use in conjunction with current Australian stanars or calculating shear loas in masonry walls; It shoul not be use or any other purpose.

14 LATERAL LOAD DISTRIBUTION IN MASONRY BUILDINGS An investigation on the istribution o win an earthquake inuce shear in loa-bearing masonry was carrie out by authors at the University o Newcastle. Numerical analysis was perorme on 12 our storey walk up apartment builings, 6 symmetrical, an 6 unsymmetrical; The total number o masonry shear walls consiere in this stuy was 432; numerical simulations using inite element metho; inclusion o 3D nonlinear behaviour o masonry & slip joints; masonry behaviour preicte through macro-moel propose by Lourenço (composite criterion by yiel suraces o Hill & Rankine); slip joints behaviour preicte by yiel surace o Mohr-Coulomb; reinorce concrete slabs assume as isotropic & linear elastic; win & earthquake loas eine by Australian Stanars. OVERESTIMATION AND UNDERESTIMATION OF SHEAR FORCES (conclusions rom Newcastle stuy) The shear loa istribution etermine by the NSA is conservative overall; The shear loa istribution etermine by NDA correlate well with consierably more simple NSA results; The shear loa istribution etermine by LEA was oun unsatisactory with the average ierences to the more realistic NSA o approximately 37% an the maximum ierences o 75.1% an -62.4%; Earthquake action i not cause any sotening o masonry but it cause signiicant slip in the joints ollowe by consierable reistribution o orces; The istribution o earthquake inuce orces in shear walls was inluence not only by the elastic stiness an arrangement o the walls, but also by the rictional capacity o slip joints, with epens on their vertical prestress.

15 V V = LEA NSA NSA V 100%. EMPIRICAL REDISTRIBUTION PROCEDURE THEORY V V = LEA NSA NSA V 100% NSA 1 LEA V = V = C % RF V LEA ~ 1 CRF = % V V = LEA NSA NSA V 100%. EMPIRICAL REDISTRIBUTION PROCEDURE THEORY (Cont.) ~ C RF = or 0 ~ C RF = or > 0

16 VALIDATION OF THE REDISTRIBUTION PROCEDURE a builing with symmetrical arrangement o shear walls - S6 x wall 2 z wall 3 z wall 4 z 6.00 wall l 1 z wa all 5 z wall 2 z wall 3 z wall 4 z z irection o w in & earthquake loa VALIDATION OF THE REDISTRIBUTION PROCEDURE results or the builing S6 Builing S6 Shear walls 1z 2z 3z 4z 5z V (kn) LEA (MPa) / (MPa) C ~ RF (-) correcte V (kn) NSA V (kn) (%) correcte (%)

17 VALIDATION OF THE REDISTRIBUTION PROCEDURE a builing with relatively uniorm istribution o mass but unsymmetrical arrangement o shear walls - C4 VALIDATION OF THE REDISTRIBUTION PROCEDURE results or the builing C4 Builing C4 Shear walls 1z 2z 3z 4z 5z V LEA (kn) (MPa) / (MPa) C ~ RF (-) correcte V (kn) NSA V (kn) (%) correcte (%)

18 VALIDATION OF THE REDISTRIBUTION PROCEDURE a builing with non-uniorm istribution o mass an unsymmetrical arrangement o shear walls - L2 VALIDATION OF THE REDISTRIBUTION PROCEDURE results or the builing L2 Builing L2 Shear walls 1z 2z 3z 4z 5z V (kn) LEA (MPa) / (MPa) C ~ RF (-) correcte V (kn) NSA V (kn) (%) correcte (%)

19 CONCLUSION An empirical proceure or more accurate calculation o the esign shear wall orces has been evelope at the University o Newcastle; It shoul be use in conjunction with the equivalent elastic analysis speciie by Australian esign stanars. It shoul not be use or any other purpose rather than esign o shear walls; The improvements in accuracy are achieve by taking into account the level o the esign compressive stress on slip joints; The proceure oes not require any aitional inormation apart rom the average overestimation an unerestimation o shear orces by the equivalent static analysis, which are 50.3% an -23.3%, respectively; CONCLUSION (cont.) The proceure has been valiate by applying it to calculate shear orces in three ierent builing types an then comparing results to the proper NSA; It appears rom this limite valiation stuy that the propose empirical proceure has the potential to ouble the accuracy o the stanar esign metho.

20 Thank you Questions