A Shaking Table Test Design on Seismic Strengthened Brick Masonry Structures

Transcription

1 5th Intenational Confeence on Advanced Design and Manufactuing Engineeing (ICADME 15) A Shaking Table Test Design on Seismic Stengthened Bick Masony Stuctues LIU Jie Ping 1, a *, LIU Chen,b and ZHANG Ling Xin 1,a 1 Institute of Engineeing Mechanics, China Eathquake Administation; Key Laboatoy of Eathquake Engineeing and Engineeing Vibation of China Eathquake Administation, Habin, Heilongjiang, 158, China Tianhua Achitectue Planning & Engineeing Limited, Shanghai 35, China a jieping_liu@16.com, b liu_chen_seu@163.com, c lingxin_zh@16.com Keywods: Extenally steel einfocement mesh mota laye, Seismic stengthened, Bick masony stuctue, Shaking table test. Abstact. The 1:4 scale model fo shaking table test was designed as a typical thee-stoey-office building stengthened with extenal steel einfocement mesh mota laye. The pocess of modeling was povided, including the elationship of model and poto stuctue, and the design pinciple of model components. The scheme of shaking table test was detemined, including simulation of wall vetical compessive stess, the atificial mass, the distibution of test instument and stain gauge, the selection of gound motions. Intoduction By the simulated eathquake shaking table test, the gound motion on the whole stuctue could be simulated, the eal seismic esponse of the stuctue would be epeated, and meanwhile the ate effect and the influence of the atificial bounday conditions would be eliminated in the pseudo-static test of components. Though the shaking table test, each stage of the stuctue mechanical popeties and damage mechanism would be known, the chaacteistics of stuctue failue would be visually obseved, and thus stuctue seismic weak links and failue modes would be detemined. In ode to study the integal seismic pefomance and the seismic stengthening effect of bick masony buildings stengthened by extenally steel einfocement mesh mota laye, the 1:4 scale model fo shaking table test was designed as a typical thee-stoey-office building in 197 s as a pototype with efeences to the ealie seismic code[1,], and stengthened with extenal steel einfocement mesh mota laye. The fist and second floo was stengthened and the thid floo was untouched as compaison. The key techniques of the pocess of modeling wee discussed, especially the detemination of bick dimension and the co-woking of the thee diffeent kinds of mateial, i.e. einfocement mesh, mota laye and bick wall. The selection of model mateial, the detemination of similitude elationship, the constuction methods of details of seismic measue and einfocement laye wee pesented. The ealizing way of stuctual membes and the details of seismic measues wee descibed in detail. The scheme of shaking table test was detemined, including simulation of wall vetical compessive stess, the atificial mass, the distibution of test instument and stain gauge, the selection of gound motions and the testing conditions. The post pocess of shaking table test was discussed fo the pepaation of the next step of simulated eathquake shaking table test. Design and manufactue of the model Relationship of model and poto stuctue. Limited by shaking table size and beaing capacity, the model selection of the pototype stuctue of two bay, which is efeed to as the model pototype. In the model pototype, thee wee two oute coss walls, one inne coss wall, two oute longitudinal walls and two inne longitudinal walls in the test. The geometic similaity constant of the model is.5, which is shown as Fig. 1. In "Regulations 15. The authos - Published by Atlantis Pess 568

2 of buildings aseismic test method" (JGJ11-96), the stength level of the egulation test block masony stuctue should be consistent with the pototype stuctue, so in this test the MU7.5 bick machine was selected. At the same time consideing the pototype of mota stength was low, the initial cacks may be ceated by the lowe stength of mota in the pocess of poduction, tanspotation, so the model mota was selected by M1. which was same as the mota of pototype. Detemined by mateial popety, the similitude law of elastic modulus test simila constant was taken by 1.. (a) Stuctual plan (b) Stuctual Elevation Fig. 1 Stuctual figue of the model In the design of educed scale model test, atificial mass is calculated by atificial mass simila ate geneally. In the model pototype, the plan dimension is 7.8m*1.78m, height is 9.9m,weight is about 5t. Fo the capacity limitation of the shaking table, The pototype test model plane size, building, total stuctue weighs about 5 t, if the human quality, completely model should be the total weight of 3 t, beyond the beaing capacity of 3 t vibation table, theefoe cannot use atificial quality model completely.on vibation table by using the gavity model, the peak acceleation and equies a high degee of effective bandwidth, at the same time fo masony stuctue model test, ignoe the gavity model of vetical compessive stess leads to the deficiency of the component failue state changes.theefoe, this expeiment adopts owe human quality model, on the basis of the existing similitude law, accoding to the vibation table consistency simila atio is used to detemine the beaing capacity and othe physical quantities of simila constant. Design pinciple of model components. The geometic similaity constant of the model was detemined by.5 and the elastic modulus simila constant was 1.. Combined with the mechanical pefomance of componts and the expeiment theoy, the design pinciple of each component was detemined. (1) Wall. The pototype wall mateial was used, i.e. MU7.5 bick made by machine and mechanism and M1. mixed mota, the model bick masony was used. The pinciple of the test model bick size was, the geometic similaity atio in the width diection was 1:4, and in thickness diection was 1:. When the masony wall was built, the hoizontal mota joint thickness should be within 3~5 mm. Accoding to YiShun yiding way, the Masony model walls with the thickness of 6mm and 9mm wee built to simulate the wall of the poto stuctue with the thickness of 4mm and 37 mm. Accoding to the code the tie bas should be set in the cones of exteio wall and wall junctions. () Reinfocement laye. In this model test, the extenally steel einfocement mesh mota laye with Ф6@3 steel was simulated by galvanized steel wie and the same typ mota. In the design of model, the geometical paametes of einfocement mota laye detemined by similitude law. The einfocement stengthening belts wee located in the ing beam of all walls on second floo, and the fou cono of oute walls and the constuctional column position on fist and second floo, which the 569

3 space of stengthened steel was half of the oiginal space. (3) Pecast slab. 1 mm thick slab was used in the pototype stuctue. Consideing the constuction convenience and the need of atificial weight, the 4 mm thick slab was used in model. Accoding to the similaity atio, the length of pecast slab plate end should be adjusted in accodance with the stuctue of the common size,which is 6 mm fo oute wall and 3 mm fo inne wall. (4) Ring beam and lintel. The C paticle concete was used in the concete component, such as ing beam and lintel, to simulate the C concete of the pototype, and steel wie was used to simulate the einfocement in concete stuctues. Accoding to the pinciple of similitude law, the equivalent einfocement was calculated. The stuctual measues in othe pats of the model, could be detemined in accodance with the actual constuction equiements and geometic similitude law. Test scheme In the testing scheme, thee wee the detemination of the model atificial mass and simila elationship, testing instuments and the distibution of stain gauge, the selection of gound motion and the detemination of input conditions, which is descibed as follows: The atificial mass of the model. The lacking atificial mass was used in the shaking table test [3,4], which the eventual atificial mass measue is shown in the Table 1. Fom the table, it can be seen that, the total mass of model was 7 tons, which was the 83% of the atificial mass. The diffeece of the failue mode caused by the lacking mass could be ignoed [5]. Stoey Table 1 The atificial mass of the model (unit: kn) Numbe of The floo atificial Type of walls Atificial mass walls mass Fist Oute coss wall Inne coss wall 9.4 Inne longitudinal wall Second Oute coss wall Real weight Inne coss wall Inne longitudinal wall Thid Oute coss wall Inne coss wall Inne longitudinal 4. wall The detemination of similitude law. Thee simila constants wee detemined in the lacking atificial model, which wee the length, elastic modulus and equivalent density. Afte that the othe simila physical constants wee calculated by using the geneal similitude laws. The simila constants of the model ae shown in the Table. 7 57

4 Geometic Mateial phycics Dynamic popeties Table The detemination of similitude law Physical paametes Relation Simila to the constant length l.5 stain ε = σ / E 1. Modulus of elasticity E 1. 3 equivalent density ρ = Mm / lm p 3.3 stess σ = E 1. foce F = σ l.65 time t = l ρ.45 fequency ω = 1/ ρ /l. aceleationm a = 1/( lρ ) 1.1 Acceleation of gavity Location of sensos. In the simulated eathquake shaking table test, the instuments wee used, such as displacement senso, acceleation senso and stain gauge, etc. Displacement sensos and acceleation sensos wee installed on the floo and each floo and oof top suface, which the hoizontal wie should be fixed on a steel fame. By displacement sensos the absolute displacement of the floos, including shea, bending and basic composition such as otation wee measued. on each floo and oof aangement of X and Y diection acceleation sensos and displacement sensos wee installed, which ae shown as in Figue. In this figue, displacement senso ae shown by the small tiangel, and aceleation senso ae shown by the aows. The Aangement of measuing points in the poject ae shown in Fig. 3, which the total numbe of stain gauges is 37. Fig. The plan aangement of displacement sensos and acceleation sensos 571

5 (a) oute longitudinal wall (b) Inne longitudinal wall (c) Oute coss wall Fig. 3 The aangement of stain gauges (d) Inne coss wall on the fist floo Gound motions Because of the simila gound motion adjustment, the time similia constant is.5, the acceleation simila constant is 1.15, and the peak value of design gound motion befoe adjustment and afte adjustment ae shown in the Table 3. Table 3 Adjustment of acceleation peak Peak value of gound motion Peak acceleation (g) Design gound motion Gound motion afte ajustment In the test, thee gound motion was seleceted, which ae El Cento, Taft and Wolong motion, whose infomation ae shown in the Table 4, and the seismic cuves ae shown in Fig Table 4 Gound motion infomation Gound motions Site Duation(s) El Cento II 53.8 Taft II 65. Wolong II

6 4 3 Acceleation [g] Time [sec] Fig. 4 El Cento gound motion time histoy cuve 15 Acceleation [g] Time [sec] Fig. 5 Taft gound motion time histoy cuve Acceleation [g] Time [sec] Fig. 6 Wolong gound motion time histoy cuve Summay The 1:4 scale model fo shaking table test was designed as a typical thee-stoey-office building in 197 s as a pototype with efeences to the ealie seismic code, and stengthened with extenal steel einfocement mesh mota laye. The fist and second stoey was stengthened and the thid stoey was untouched as compaison. The key techniques of the pocess of modeling wee discussed, especially the detemination of bick dimension and the co-woking of the thee diffeent kinds of mateial, i.e. einfocement mesh, mota laye and bick wall. The selection of model mateial, the detemination of similitude elationship, the constuction methods of details of seismic measue and einfocement laye wee pesented. The ealizing way of stuctual membes and the details of seismic measues wee descibed in detail. The scheme of shaking table test was detemined, including simulation of wall vetical compessive stess, the atificial mass, the distibution of test instument and stain gauge, the selection of gound motions and the testing conditions. Acknowledgements This study is financially suppoted by NSFC with gant No Refeences [1] Pofessional Standad of the People s Republic of China. GB53-9 Standad fo seismic appaisal of buildings [S]. Beijing: China Achitectue and Building Pess, (9) (in Chinese) [] Pofessional Standad of the People s Republic of China. GB511-1 Code fo seismic design of buildings [S]. Beijing: China Achitectue and Building Pess, (9) (in Chinese) [3] Zhang Minzheng, Meng Qingli, Liu Xiaoming. Study on Shaking Table Test of Buildings [J]. Engineeing Seismic. 3, (4): (in Chinese) 573

7 [4] Jiang Lu, Li Xu, Ma Renle. Shaking Table Test Scaled Model Design fo a Fou-stoy School Building inmasony Stuctue with Pecast Slabs [J]. Jounal of Sijiazhuang Tiedao Univesity (Natual Science), 11, 4(): (in Chinese) [5] Zhang Minzheng. Study on Similitude Laws fo Shaking Table Tests [J]. Eathquake Engineeing and Engineeing Vibation, 1997, 17():5-58. (in Chinese) 574