Application of Bituminous-Concrete with Frame-Separation in Steel Bridge Deck Pavement

Transcription

1 Proc. of the 9th WSEAS Int. Conf. on Mathematical an Computational Methos in Science an Engineering, Trinia an Tobago, ovember 5-7, Application of Bituminous-Concrete with Frame-Separation in Steel Brige Deck Pavement ZHAG Ronghui, HE Yuanhang, Lv Huiqing Faculty of Construction Guangong University of Technology Aress: Faculty of Construction Guangong University of Technology, Guangzhou China Abstract: This paper escribes a new type of bituminous concrete brige eck pavement with frame separation, the lower layer of which is esigne to have a frame-separation structure in orer to obtain bituminous concrete units that are inepenent from each other, while the upper layer is pave with fiber bituminous concrete. Pavement with this new structure has been successfully applie to a steel brige with ouble ecks for ual purposes of highway an railway uses, which is able to restrain the pavement eformation within an acceptable limit an settle the maintenance an repair problem of the brige. Keywors: Frame-separation; bituminous concrete; Deck pavement steel brige with ouble ecks; Deformation Introuction Most of briges with ual purposes for both highway an railway uses in China were built in the years before 70s' of 20th century, which were constructe for a primary purpose of railway use together with a seconary purpose of highway use. Most of the briges with such style were esigne to have steel truss structures, where the brige ecks were lai on the steel plates forming the roof of the steel truss or on the pre-casting reinforce concrete slabs. As the eck pavement of the brige vibrates rather greatly, the eck pavement is very easy to be amage, an in case of amage, the repair is very ifficult to carry out. This paper researches the vibration of Guangong Xiiang Highway-Railway Double-Level Brige, purpose of it is to analyze the effects of vibration of the brige eck on the payment structure an puts forwar the relate repairing metho. highway use, with a main brige of 720 meters in length an a spacing of 6 meters between two aacent piers. Vibration test points of the brige eck are set at locations between the first pier an the secon pier. Accoring to eflection calculation of the brige beams an vibration test of the brige eck, when a train with loa passes by the brige, the maximum eflection between cross-points of the two piers is 5.6 cm, the relative vertical vibration amplitue of the testing section of the brige eck is 5.9 mm, the horizontal Lateral vibration amplitue is.8 mm, the vibration frequency is 0 Hz an 2 Hz respectively, which mean that a material point in the brige eck vibrates relatively an irregularly 0 times per secon, as well as upwars an ownwars over a vertical istance of 5.9 mm. 2 Theory Locate in Zhaoqing City of Guangong Province, Guangong Xiiang Brige is a brige with ouble ecks for ual purposes of highway an railway uses (See Figure.a an Figure.b), the main eck of which is for railway use, while the upper eck of which is for

2 Proc. of the 9th WSEAS Int. Conf. on Mathematical an Computational Methos in Science an Engineering, Trinia an Tobago, ovember 5-7, k( ) n = () [2] 2. Vibration of the Brige Increases the Stress to the Brige Deck Pavement Assuming that the brige eck pavement is an elastic boy, meanwhile, the concrete of the eck pavement an the steel truss of the brige eck are inclue in a same vibration system, then, the stress cause by force vibration is: B = ( + ) () [] Where, represents actual stress to the pavement of generic roa; represents stress arising from vibration of a brige with ual purposes for highway an railway uses; B represents integrate vibration amplitue, which is 5.9 mm base on actual measurement; represents average eflection of the steel truss. The spacing between two aacent expansion Joints is 2m, an the average eflection of the steel truss is 20 mm. Replace symbols in the formula with ata, an the result is: 5.9 = ( + ) =.295 (2) 20 The result inicates that the vibration of a brige with ual purposes for highway an railway uses causes the stress of the brige eck pavement to increase to.295 times its original value, therefore, when carrying out esign of pavement materials an structure layer for a brige, 0% of aitional effects cause by vibration shoul be taken into account so as to meet the special requirement by the brige eck pavement. n2 = k( ) (4).295 Where represents action times of loa that can reach the fatigue failure of bituminous concrete of generic brige eck; represents action times of loa that can reach the fatigue failure of bituminous concrete of generic brige eck that is cause by vibration; k represents characteristic coefficient of compositions comprising the bituminous concrete; n represents graient factor, the n of moifie bituminous concrete is.5 ~ 2.5. In case of the same compositions comprising bituminous concretes, unchange K an approximate graient factor n, the aitional stress cause by vibration is: =,an accoring to formula(), the result is:.295 n2 k( ).295 = 0.55~0.65 (5) n k( ) = (0.55~ 0.65) (6) It is obvious that the fatigue lifetime of brige eck pavement is only 55~65% of that of generic roa pavement. Accoring to the above-mentione test an analysis, traitional metho for maintenance an repair can not fully solve the problems of Xiiang Highway-Railway Double-Level Brige. Experiment The vehicle lane on the upper eck of Xiiang Brige is combine by pre-casting reinforce concrete slabs with imension 4.5 meters in length an.6 meters in with. The spacing between aacent expansion Joints is 2m, an total 6 pieces of pre-casting slabs have been use. The original pavement of the brige eck for highway inclues a layer of ferrocement concrete with thickness of 5cm plus a wearing layer of bituminous concrete with thickness of cm. See Figure 2 for the structure of the eck pavement Repeately Bening an Deforming of Brige Deck Pavement Results in Roa Pavement Fatigue an Shortens Service Lifetime Uner a conition of controlle stress, action times of loa that can reach the fatigue failure of the bituminous concrete is: 2

3 Proc. of the 9th WSEAS Int. Conf. on Mathematical an Computational Methos in Science an Engineering, Trinia an Tobago, ovember 5-7, The average aily traffic flow has reache 0000 vehicles, an after its operation for tens of years, most portion of the bituminous wearing layer has been amage, ferrocement concrete section has been amage, an as a result of which, rainwater has infiltrate to the steel railway truss, thus amages have been cause to railway facilities. As the eck pavement on the brige mainly shows a characteristic of rigiity, its maintenance an repair can only be conucte with bituminous concrete uner the conition or requirement that no impact or obstruction may be cause to current traffic. In orer to settle the technical problems involve in maintenance an repair more successfully, this paper suggests a structure scheme shown in Figure an Figure Propagation of vibration in separate bituminous concrete is obstructe an thus fatigue strength cause by vibration is reuce Figure 5.a illustrates vibration propagating in a same matter, while Figure 5.b shows vibration propagating in a separate matter, which reveals that the propagation of vibration is obstructe at the separation point an thus the vibration attenuate quickly, in other wors, the affects on Block B cause by vibration arising from Block A of the separate bituminous concrete has been lightene. Elasticity moulus of the polysulfie rubber moifie epoxy resin frame-separation concrete is E rubber =0 0 Mpa. Elasticity moulus of the bituminous concrete E bitumen =.2 0 Mpa. As each of the two materials has an elasticity moulus ifferent from the each other, a portion of the energy is consume uring the propagation course of the kinetic energy, an therefore, lesser vibration energy is propagate. This is a measure suitable for isolation of vibration an will be helpful in increasing fatigue lifetime. In this scheme, a glass oist waterproof stratum boune with moifie epoxy is applie to the surface of pre-casting slabs comprising the brige eck. Moifie bituminous concrete is applie to the lower layer, an the bituminous concrete stratum is separate as rectangle units with imension of 8 m m by means of polysulfie rubber moifie epoxy resin concrete. A fiber reinforcement bituminous concrete stratum with a thickness of cm is applie to the upper layer, which forms a frame structure. The with of a frame-separation concrete unit is 5cm, with a epth equal to the lower layer, an the construction metho for which is as follows: Before paving bituminous concrete, place a channel steel member with a cross-section imension of 5cm 5cm at an expecte separation location, lay an pave bituminous concrete, an then roll it to form its shape. After completion of the final rolling, take out the channel steel members to obtain a frame channel in the bituminous concrete stratum, then, inect the polysulfie rubber moifie epoxy resin to form a frame. 4 Results an Discussion 4.2 Bening-tensile stress an strain of separate bituminous concrete are reuce an thus the fatigue lifetime is increase Separation of bituminous concrete by means of frame is able to reuce fatigue tensile stress of the brige eck pavement an is also able to increase the fatigue lifetime of the brige eck pavement, which may be further prove through a fatigue test or enurance test on bituminous concrete. Bening-tensile eformation an bening-tensile stress of bituminous concrete is expresse as below: ap = (7) [2] 2 bh Where, a represents the horizontal istance from the loa to the support; P represents the ynamic loa that bens the beam; b represents the with of the test piece or test sample; h represent the thickness of the test piece or test sample. The test results show that, incase that P, namely the ynamic loa bening the girer keeps unchange, while a, namely the horizontal istance from the loa to the support shortens, then,, namely the fatigue bening-tensile stress also reuces accoringly. As shown in Figure 6, when the test beam has been ivie into three segments, the istance from the loa on each segment to the support also reuces by /.

4 Proc. of the 9th WSEAS Int. Conf. on Mathematical an Computational Methos in Science an Engineering, Trinia an Tobago, ovember 5-7, Differences exist between the test beam an the brige eck slabs. When the slab has shortene by / in length, the fatigue bening-tensile stress on the bottom of the slab reuces by0~5 % only. Calculation base on formula ()inicates that action times of loa will increase by 20-50% after the slab surface has been separate. In aition, as euce from the basic characteristics of the materials, we know that, when E, namely the bening-tensile moulus of bituminous concrete materials keeps unchange, the level of fatigue stress lowers, an its strain ε also lowers accoringly. The above-mentione experiment an analysis reveal that separating bituminous concrete of brige eck pavement is one kin of the effective metho whereby to lower stress level, reuce eformation, an eliminate fatigue failure. 4. Deformation of bituminous concrete within the separation frame restraine Calculation base on the expansion an shrinkage eformation of materials cause by temperature variation reveals that the variation of materials by temperature variation is: = L α L (8) Where: α represents the linear expansion coefficient of a material work-piece, an for bituminous concrete, α = ; for cement concrete, α = L represents the length of a material work-piece ; L represents the expansion variation. The experiment shows that α is harly affecte by temperature, while L will rise when the length of a material work-piece gets large. Therefore, reucing the length or with of a material work-piece will help greatly to reuce the linear expansion variation. Figure 7 inicates that when two kins of compoun material work-pieces stretch freely, the longer the length of a work-piece is, the larger its variation L is (See Figure 7.a). As the eformation of a bituminous concrete stratum will be restraine after it has been separate,the overall eformation of a bituminous concrete stratum will accoringly reuce to / as much as its original eformation(see Figure 7.b).Deformation variation after separation: L = L = L α (9) Research an analysis inicate that separation of the brige-eck bituminous concrete, with frames inserte into seams between two aacent block units on which a layer of fiber reinforcement bituminous concrete is pave, not only can restrain the eformation of the bituminous concrete pavement an weaken propagation of vibration in the bituminous concrete, but also can increase the overall strength of the brige eck pavement an improve the overall anti-vibration ability. 4.4 Two-Dimensional Sizes of Bituminous Concrete Structure with Frame-Separation The measure escribe in this paper is aime at the maintenance an repair of Xiiang Highway-Railway Double-Deck Brige for the purpose to reuce the effects of vibration in brige eck on the pavement.. Theoretically, the smaller a separation size is, the more the avantage is. But a too small separation size will increase the costs an make the construction ifficult.. For this reason an base on the actual conitions in connection with imensions of brige eck of Xiiang Brige an the esign wheel space of roa vehicle, i.e. the wheel space of a heavy vehicle is 6.5m, the wheel space of a semi-trailer is 8.8m, total with is 2.5m, the two-imensional separation sizes suitable for the maintenance an repair of the Xiiang Brige are etermine as ( Figure ): 8m long an m wie. Vibration tests have prove that separating a single-boy material is one of the measures whereby to facilitate or improve the fatigue vibration-resistance of the pavement. 5 Conclusion Base on the results of lab experiments, a comparison test on three ifferent schemes for the maintenance an repair of Xiiang Brige was carrie out in December The test sample use in each scheme is 96 meter in length an 9 meter 4

5 Proc. of the 9th WSEAS Int. Conf. on Mathematical an Computational Methos in Science an Engineering, Trinia an Tobago, ovember 5-7, in with. After six years of operation, the teste segment of brige-eck pavement mae of bituminous concrete with frame separation is still in goo status, while the teste segment of brige-eck pavements in the other two schemes have been amage to ifferent extent.. Practice has testifie that the above mentione maintenance an repair technique is effective for a highway-runway brige that vibrates frequently an greatly. Separating brige eck pavement mae of bituminous concrete is a new topic, where the frames for separation shows the function of obstructing the propagation of vibration, thus, the bening stress to the brige eck is reuce,, an therefore lower an increase the acting times of the fatigue failure, which may be rate as one measure where by to exten the service lifetime of the pavement.. References: [] the Teaching an Research Section of Mechanics of Materials uner Xi an Jiaotong University.Mechanics of Materials[M]. Xi'an: Jiaotong University Press, 979. [2] Fang Fusen. Pavement Engineering [M].Beiinbg: Renmin Jiaotong Press,