• <tr id="yyy80"></tr>
  • <sup id="yyy80"></sup>
  • <tfoot id="yyy80"><noscript id="yyy80"></noscript></tfoot>
  • 99热精品在线国产_美女午夜性视频免费_国产精品国产高清国产av_av欧美777_自拍偷自拍亚洲精品老妇_亚洲熟女精品中文字幕_www日本黄色视频网_国产精品野战在线观看 ?

    Experimental study on the static load performance of steel-concrete composite external joints after fatigue loading

    2023-12-05 07:23:34TanYingliangZhuBingCuiShengai

    Tan Yingliang Zhu Bing Cui Shengai

    (School of Civil Engineering,Southwest Jiaotong University,Chengdu 610031,China)

    Abstract:To study the effect of fatigue loading on the static performance of the external joint of the steel truss web-concrete composite (STWCC) structure,three joint models were designed and constructed with a scale ratio of 1∶3.The failure mode and load-displacement curve of the joint were obtained through static load testing and post-fatigue static load testing.The load-strain curve of the gusset plate was plotted.The changes in mechanical performance indexes,such as the yield load,ultimate load,rigidity,and ductility coefficient of the joint,were comprehensively analyzed.The results showed that the gusset plate was the key load-bearing component of the STWCC joint,and gusset plate failure was the typical failure mode of the external joint.Although fatigue load had a minor impact on the mechanical performance of the joint before yielding,it exerted a remarkable impact post yielding.Compared with the specimen subjected to only static loading,the specimen without fatigue failure exhibited a 4% lower ultimate bearing capacity and a 28% lower ductility coefficient,while the specimen with fatigue failure exhibited a 25% lower ultimate bearing capacity and a 52% lower ductility coefficient.Fatigue cracks induced stress redistribution in the gusset plate and increased the strain in the regions without fatigue cracks.The strain increase rate decreased with increasing distance from the fatigue cracks.

    Key words:steel truss web-concrete composite structure; composite external joints; model test; static load after fatigue; mechanical performance

    The steel-concrete composite structure,combining the advantages of both steel and concrete,has been widely implemented in recent years[1-4].The steel truss web-concrete composite (STWCC) bridge is a novel architectural structure that has emerged in the past few years.It consists of top and bottom concrete slabs,steel truss webs,and prestressed steel bundles.In this bridge design,steel truss webs replace the webs of concrete box girders,thereby circumventing the issues caused by concrete web cracking.This design improves structural permeability,reduces structural self-weight,increases bridge span,and reduces substructure size.Owing to these advantages,the STWCC structure has been widely implemented in bridge engineering,with examples including the Arbois Bridge,Bras de la Plaine Bridge,Shinchun Bridge,and Kinokawa Bridge[5-6].However,this structure is still in its early stages in China.The mechanical performance of the joint is crucial for the safety and durability of the entire structure[7-10].The STWCC joint connects the steel truss web with the top and bottom concrete slabs,playing a key role in force transmission and serving as one of the critical components of composite truss bridges.

    The STWCC joint can be classified into two types: the embedded joint and external joint.In the former type,the steel truss webs are directly embedded into the concrete chord members.In the latter type,the steel truss webs are connected to the chord members through gusset plates.Extensive research has been conducted on the mechanical performance of the STWCC joint.Furuichi et al.[11]conducted an experimental study on an embedded steel box joint to investigate its load-bearing capacity and failure mode.This type of joint was utilized in the first STWCC bridge in Japan,known as the Kinokawa Bridge.Jung et al.[10]performed static load testing on various embedded joints and observed that all joints lost their load-bearing capacity due to concrete damage.Xue et al.[12]conducted static load testing on the truss joint with encased concrete to examine the load-bearing ratio between the steel truss and encased concrete.Duan et al.[13]developed a PBL-tubular joint and conducted static load testing,revealing that the joint ultimately failed due to concrete shear damage in the intersection zone of the steel tubes.Zhou et al.[14]conducted static load testing on an embedded joint,which eventually lost its load-bearing capacity owing to severe chord cracking and compression buckling of the steel truss webs.Yin et al.[15]compared the static performances of embedded and external joints,revealing that the chord members of embedded joints exhibited earlier cracking than those of external joints.In summary,premature chord cracking poses challenges to the structural safety and durability of bridges.Zhou et al.[16]conducted 1∶3 scale static load testing on external joints,which resulted in joint failure owing to compression buckling of the gusset plate.By strengthening the gusset plate,the failure mode of the joints shifted to the gusset plate tensile fracture.Zhou et al.[17]also conducted numerical simulations and theoretical analysis of the rotational stiffness of external joints,proposing a formula for calculating their initial rotational stiffness.Tan et al.[18]performed 1∶2 scale tests on external joints to validate their excellent load-bearing capacity and to investigate the strain distribution across each component.He et al.[19]and Shao et al.[20]conducted scale tests on the external joints of a steel truss web-ultrahigh-performance concrete structure to verify the feasibility of applying external joints to composite arch bridges.Jung et al.[5]and Liu et al.[21]conducted fatigue performance experiments on embedded joints but did not conduct post-fatigue static load tests.

    These scholars have investigated various forms of STWCC joints and have achieved remarkable results.The studies primarily focused on embedded joints,with limited research on the fatigue performance and post-fatigue static loading performance of external joints.Therefore,in the present research,building upon Ref.[22],we conducted post-fatigue static load testing on the external joints of the first railway STWCC box girder bridge in China to investigate their static performance after fatigue loading.The study examined the failure mode,load-displacement relationship,ultimate bearing capacity,post-yield deformation capacity,and strain distribution across the gusset plate.This paper can serve as a reference for the design of external joints in STWCC bridges.

    1 Experiment

    1.1 Specimen design

    According to the overall design of the first double-track high-speed railway STWCC box girder bridge in China,as outlined in Ref.[23],the joint with the highest gusset plate stress amplitude was selected.Three identical external joint models (see Fig.1(a)),namely S1,F1,and F2,were designed and fabricated at a scale ratio of 1∶3.Following the principle of similitude,the concrete chord size for the scaled joint was 1764 mm×334 mm×367 mm (length×width×height); the gusset plate size was 776 mm×629 mm×16 mm (length×width×thickness); the steel web section size was 268×184 mm with a thickness of 20 mm; the longitudinal steel bar diameter was 12 mm,and the stirrup diameter was 8 mm.Additionally,18 holes with a diameter of 40 mm were precut on the gusset plate,and 14 mm diameter steel bars were inserted through the holes to serve as PBL shear connectors.The joint models are depicted in Figs.1(b) and (c).

    (a)

    1.2 Mechanical properties of raw materials

    The materials used for the scaled models and the prototype were of the same grade.The steel structure,concrete chord member,and rebar grades were Q370qE,C50,and HRB400,respectively.The mechanical properties of the raw materials for concrete and rebar were measured in accordance with Chinese standards (GB/T 50081—2019[24]and GB/T 228.1—2010[25]),as shown in Tab.1.The mechanical properties of the Q370qE steel plates were measured by the commissioned steel structure manufacturer; the yield strengthfywas 452 MPa,the tensile strengthfuwas 583 MPa,and the elastic modulusEwas 206 GPa.

    Tab.1 Material mechanical properties

    1.3 Measurement-point layout and loading scheme

    The layout of measurement points is illustrated in Figs.1(b) and (c).A laser displacement sensor was positioned at one end of the concrete chord to measure the joint displacement,while strain rosettes (B22 to B30) were placed on the gusset plate to monitor its strain.The loading scheme for the external joint models is depicted in Fig.2.Horizontal loads were applied to the concrete chord using a hydraulic jack or a mechanical testing and simulation (MTS) system anchored to the reaction wall.The steel truss web was connected to the steel base through axis pins,and the steel base was connected to the reaction floor using steel bolts.To investigate the static performance of the external joints after fatigue loading,Specimen S1 underwent only static load testing,while Specimens F1 and F2 were subjected to fatigue testing before static load testing.

    (a)

    1.3.1 Static load test

    Prior to formal loading,preloading was conducted (maximum load of 1 600 kN) to eliminate assembly gaps and calibrate the loading equipment.Subsequently,a hydraulic jack with a maximum capacity of 6 300 kN was utilized for graded loading.The load increment for each grade was 400 (loadF<2 000 kN),200 (2 000 kN≤F≤3 000 kN),and 100 kN (F>3 000 kN).After each loading grade,the load was held for 5 min,and data were then collected.

    1.3.2 Fatigue test

    To determine the influence line of internal forces for the most critical joint,a finite element model of the entire bridge was developed.The internal force history curve of the joint under the China railway passenger transport standard live load was obtained.Through the rain flow method,the amplitude of internal forces and the corresponding number of loading cycles were determined.According to the Palmgren-Miner linear cumulative rule,the equivalent loading amplitude for 2 million cycles was calculated.The equivalent loading amplitude for the scaled joint was determined as 260 kN,and the corresponding design stress amplitude for the joint plate was 53.2 MPa,following the similarity principle.The MTS loading system was used for the fatigue tests.Prior to the formal fatigue test,12-grade preloading (maximum load of 600 kN) was conducted.Specimen F1 was subjected to fatigue loading for 2.5 million cycles at the designed stress amplitude of 53.2 MPa,with upper and lower loading limits of 40 and 300 kN,respectively.Specimen F2 was subjected to fatigue loading for 2.5 million cycles with a stress amplitude of 73.6 MPa (1.4 times the designed value) and upper and lower loading limits of 40 and 400 kN,respectively,at a loading frequency of 3.5 Hz.After every 5×105cycles of loading,the loading was halted,and a static load test with a maximum load of 600 kN was conducted.Following the fatigue test,Specimens F1 and F2 were subjected to post-fatigue static load testing,following the loading scheme of Specimen S1.

    2 Experimental Phenomena and Failure Mode

    2.1 Static load test

    According to the findings from the static load testing of external joints[22],the failure process of Specimen S1 under static loading can be described.Initially,when the load was below 3 800 kN,Specimen S1 remained intact without any visible damage.As the load reached 3 800 kN,the gusset plate and the pressed steel truss web experienced compression,resulting in the peeling of paint from the surface of the gusset plate.At a load of 4 000 kN,a crack with a horizontal angle of 23° appeared in the middle of the B side of the chord.When the load reached 4 400 kN,the splice plate with hand holes on the pressed side buckled.A further increase in the load to 4 800 kN caused the high-strength bolts connecting the gusset plate and the splice plate to slip (see Fig.3(a)).Upon reaching a load of 5 200 kN,the chord cracks rapidly expanded,and the splice plate with hand holes exhibited tensile necking (see Fig.3(b)).Eventually,Specimen S1 was damaged owing to the tensile fracture of the gusset plate in tension (see Fig.3(c)).The joint failure mode is illustrated in Fig.3.

    (a)

    2.2 Fatigue test

    During the fatigue test,Specimen F1 was subjected to 2.51 million cycles of loading with the designed stress amplitude,and it did not exhibit any fatigue failure.Specimen F2 was subjected to fatigue loading with a stress amplitude of 1.4 times the designed value.After 1.4 million cycles of loading,through-thickness cracks emerged in the junction area of gusset plate B near the loading end and the ribbed stiffener of the gusset plate.The fatigue loading continued until the number of cycles reached 2.51 million.The fatigue cracks in Specimen F2 did not propagate further,and no damage was observed in other members,such as the concrete chord and steel truss web.The details of the fatigue cracks of Specimen F2 are shown in Fig.4.The position of the fatigue cracks in Specimen F2 coincided with the fracture location of the gusset plate in Specimen S1.The fatigue cracks occurred at the junction of the concrete chord and the steel gusset plate and the junction of the ribbed stiffener and the steel gusset plate.Moreover,the presence of high-strength bolt openings also contributed to the weakening of the gusset plate,turning the region where fatigue cracks occurred into a critical load-bearing part of the external joints in the STWCC structure.

    Fig.4 Fatigue crack details of Specimen F2

    2.3 Post-fatigue static load test

    Post-fatigue static load testing was conducted on Specimens F1 and F2 following the loading scheme of Specimen S1.When the load was below 4 000 kN,Specimen F1 showed no significant damage.As the load reached 4 000 kN,cracks appeared on the B side of the chord,and these cracks expanded as the load increased.At 4 500 kN,cracks emerged on the A side of the chord,and the splice plates with hand holes exhibited necking and warping on the tension and compression sides,respectively.When the load reached 5 000 kN,the chord cracks intensified,the high-strength bolts experienced noticeable slippage,the gusset plate underwent significant deformation,and necking occurred in the gusset plate on the tension side.We tried to further increase the load but failed to stabilize the load.Considering that Specimen F1 could not withstand a larger load,its ultimate bearing capacity was 5 000 kN.The static failure mode of F1 resembled that of Specimen S1,with lower damage levels observed in each component.The failure mode of Specimen F1 is depicted in Fig.5(a).

    (a)

    When the load was below 3 600 kN,Specimen F2 did not exhibit any noticeable damage.However,once the load reached 3 600 kN,the fatigue cracks on gusset plate B began to expand.At 3 900 kN,the high-strength bolts displayed significant slippage,the fatigue crack width further increased,and dislocation appeared along the loading direction.Eventually,the fatigue crack width reached 4 mm,with a dislocation of 3 mm along the loading direction.As the cracks of Specimen F2 gusset plate were too wide,there was a risk of sudden collapse.Therefore,for safety reasons,no higher external loads were applied,and the ultimate bearing capacity of Specimen F2 was determined to be 3 900 kN.The failure mode of Specimen F2 is depicted in Fig.5(b).

    3 Experimental Results and Discussion

    3.1 Load-displacement curve

    The load-displacement curves of Specimens S1,F1,and F2 are presented in Fig.6(a).The failure process of the external joints in the STWCC structure under static loading can be divided into four stages (see Fig.6(b)).Taking the failure process of Specimen S1 as an example,the four stages are as follows: 1) Gap elimination stage.In this stage,despite the preloading conducted before the static load testing,there existed an assembly gap.Consequently,the slope of the load-displacement curve in this stage was smaller than those in the subsequent stages.The load increment in this stage was 400 kN,and the corresponding displacement ranged from 0 to 3.54 mm.2) Elastic stage.In this stage,the joint displacement increased linearly with the load.The load increment was 2 800 kN,and the corresponding displacement ranged from 3.54 to 10.90 mm.3) Elastic-plastic stage.In this stage,the displacement exhibited nonlinear growth with the load,and the displacement rate increased.The load increment was 600 kN,and the corresponding displacement ranged from 10.90 to 14.36 mm.4) Plastic stage.In this stage,the displacement increased rapidly,and the slope of the load-displacement curve decreased.The load increment was 1 400 kN,and the corresponding displacement ranged from 14.36 to 59.01 mm.

    (a)

    Fig.6 demonstrates that the load-displacement curves of Specimens S1,F1,and F2 initially overlapped,particularly during the elastic stage.However,discrepancies emerged in the later stages of loading,particularly after entering the plastic stage.When the load was below 3 200 kN,the disparities in the load-displacement curves were minimal.Once the load surpassed 3 200 kN,the displacement of Specimen F2 increased rapidly.At a load of 3 600 kN,the displacements of Specimens F1 and F2 were 99% and 145% of that of Specimen S1,respectively.The differences in the load-displacement curves between Specimens F1 and S1 became prominent after the load exceeded 3 800 kN.At a load of 4 200 kN,the ratio of the displacement of Specimen F1 to that of Specimen S1 was 69%.Furthermore,under loading conditions exceeding 3 800 kN,the displacement of Specimen F1 remained consistently smaller than that of Specimen S1 at all load levels.The displacement values of the specimens under different loads are presented in Tab.2.

    Tab.2 Displacement of the specimens

    3.2 Static performance indexes

    Tab.3 demonstrates the static performance indexes of the three specimens,including yield loadNy,ultimate loadNu,joint stiffnessK,ductility coefficientμ,and displacementD.Neis the load borne by the joint in the elastic stage,and the corresponding displacement isDe;Nyis the yield load determined by the farthest point method[26],and the corresponding displacement is the yield displacementDy;Nuis the ultimate load,and the corresponding displacement is the ultimate displacementDu;Kis the initial stiffness used to evaluate the elastic deformation resistance of joints,which can be regarded as the slope of the load-displacement curve in the elastic stage; for Specimen S1,K=Ne/De=(3 200-400)/(10.90-3.54)=380.43 kN/mm;μis the ductility coefficient used to evaluate the deformation capacity of the joint after yielding,μ=Du/Dy.As shown in Tab.3,Specimen F1 exhibited a 3% increase in yield load and a 5% decrease in initial stiffness compared with Specimen S1.Specimen F2 experienced an 11% reduction in yield load and an 8% decrease in joint stiffness compared with Specimen S1.When the joints reached the yield point,Specimen F1 demonstrated a 4% decrease in ultimate load and a 28% decrease in ductility coefficient compared with Specimen S1.Similarly,Specimen F2 exhibited a 25% decrease in ultimate load and a 52% decrease in the ductility coefficient compared with Specimen S1.These results indicate that fatigue loading had a more pronounced impact on the post-yield static performance of the external joints than on the pre-yield static performance.The fatigue-induced cracking of the gusset plate significantly reduced the ultimate bearing capacity and deformation capacity of Specimen F2 after yielding.In summary,fatigue loading has a relatively smaller effect on the pre-yield static performance of the composite external joints but exerts a more significant influence on the post-yield static performance.

    Tab.3 Static performance indexes of the specimens

    3.3 Load-strain curves of gusset plate

    Fig.7 illustrates the load-strain curves of the gusset plates for Specimens S1,F1,and F2.Only the results with strains below 3.5×10-3are presented,as the strains of the gusset plates exceeded the ultimate strength of the steel in the later stages of loading.As shown in Fig.7,the load-strain curves of Specimen F1 and S1 gusset plates essentially overlapped,and the displacement growth trends were similar; however,a clear difference between the strain of Specimens F2 and S1 suggested that the post-fatigue static performance of external joints of the STWCC structure without fatigue damage did not undergo an extensive change compared with that of the joints not subjected to fatigue loading.The strain of B22 in Specimen F2 was less than that of B22 in Specimen S1 (see Fig.7(a)).Conversely,the strain of B23 and B26 in Specimen F2 was greater than that of B23 and B26 in Specimen S1 (see Figs.7(b) and (c)).The strain values of measurement points B24 to B27 exhibited a similar pattern to that of B23.Fig.7(d) presents the strain distribution of measurement points B22 to B27 for Specimens S1 and F2 at different load levels: 800,2 000,and 2 800 kN.At a load of 2 000 kN,the strain values at measurement points B22 to B27 in Specimen F2 exhibited an increase of-58%,57%,24%,20%,19%,and 20%,respectively,compared with the corresponding measurement points in Specimen S1.This indicates that stress redistribution occurred and that the load that should have been borne by the area experiencing fatigue cracks was transferred to other areas of the gusset plate.Furthermore,the growth of strain from B23 to B27 gradually slowed down,suggesting a diminishing influence of fatigue cracks on the strain distribution of the gusset plate with increasing distance from the fatigue cracks.At loads of 800 and 2 800 kN,the strain distribution of the gusset plate for Specimen F2 exhibited a similar pattern to that observed at 2 000 kN.

    (a)

    4 Conclusions

    1) Gusset plate failure occurred in static load tests,fatigue tests,and post-fatigue static load tests,and the failure of the gusset plate remarkably impacted its mechanical performance.The gusset plate was the key load-bearing component of the external joints.

    2) The failure process of the joints under static loading comprised four stages: the gap elimination stage,elastic stage,elastic-plastic stage,and plastic stage.Fatigue loading had a more pronounced effect on the post-yield load-displacement relationship than on the pre-yield load-displacement relationship.

    3) The mechanical performance of the joints after yielding was considerably influenced by the fatigue load.Fatigue loading resulted in a degradation of the ultimate bearing capacity and a reduction in the ductility coefficient to varying degrees.The static performance of the joints with fatigue failure in the fatigue tests was more substantially impacted by the fatigue load.Compared with the joint subjected to only static loading,the joints without fatigue failure exhibited a 4% lower ultimate bearing capacity and a 28% lower ductility coefficient,whereas the joints with fatigue failure exhibited a 25% lower ultimate load capacity and a 52% lower ductility coefficient.

    4) Fatigue cracks in the gusset plate caused stress redistribution within the joint.This led to an increase in strain in other areas of the gusset plate,and the growth of strain slowed down as the distance from the fatigue cracks increased.

    天堂中文最新版在线下载| 久久人人爽av亚洲精品天堂| 欧美久久黑人一区二区| 9热在线视频观看99| 亚洲成人免费av在线播放| 精品国产美女av久久久久小说| 国产有黄有色有爽视频| 色综合欧美亚洲国产小说| 丝袜美足系列| av中文乱码字幕在线| 亚洲片人在线观看| 欧美激情高清一区二区三区| 97超级碰碰碰精品色视频在线观看| 看免费av毛片| 国产一区二区三区视频了| 亚洲精品一二三| 久久久国产精品麻豆| 午夜精品在线福利| 50天的宝宝边吃奶边哭怎么回事| 亚洲专区字幕在线| 亚洲精品美女久久久久99蜜臀| 久久久久久久久久久久大奶| 国产成人啪精品午夜网站| 国产精品乱码一区二三区的特点 | 久久精品91蜜桃| av欧美777| 亚洲七黄色美女视频| 免费在线观看亚洲国产| 丁香六月欧美| 悠悠久久av| 在线免费观看的www视频| 日韩人妻精品一区2区三区| 久久草成人影院| 韩国av一区二区三区四区| 成人特级黄色片久久久久久久| 另类亚洲欧美激情| 99riav亚洲国产免费| 欧美中文综合在线视频| 精品少妇一区二区三区视频日本电影| 精品乱码久久久久久99久播| 亚洲色图 男人天堂 中文字幕| 国产片内射在线| 曰老女人黄片| 一区福利在线观看| 久久久久九九精品影院| 一级毛片女人18水好多| 欧美日韩黄片免| 久久精品国产亚洲av香蕉五月| 日韩欧美免费精品| 色综合欧美亚洲国产小说| netflix在线观看网站| 少妇粗大呻吟视频| 精品乱码久久久久久99久播| 免费看十八禁软件| 人妻丰满熟妇av一区二区三区| 亚洲中文日韩欧美视频| 国产精品国产高清国产av| 美女福利国产在线| cao死你这个sao货| 一边摸一边抽搐一进一小说| 日本五十路高清| 黄色毛片三级朝国网站| 久久精品国产综合久久久| 在线观看舔阴道视频| 久久 成人 亚洲| 成人精品一区二区免费| 99久久99久久久精品蜜桃| 久热爱精品视频在线9| 午夜视频精品福利| 人人妻人人爽人人添夜夜欢视频| 99riav亚洲国产免费| 久久影院123| 成年版毛片免费区| 宅男免费午夜| 一区在线观看完整版| 免费观看精品视频网站| 精品国产亚洲在线| 女性生殖器流出的白浆| 欧美丝袜亚洲另类 | 97人妻天天添夜夜摸| 一a级毛片在线观看| 欧美成人性av电影在线观看| 搡老乐熟女国产| 在线观看66精品国产| 亚洲国产精品999在线| 欧美激情高清一区二区三区| 国产精品 欧美亚洲| 亚洲自偷自拍图片 自拍| 国产精品影院久久| 性色av乱码一区二区三区2| 久久久国产成人精品二区 | 亚洲欧美一区二区三区黑人| 国产精品亚洲av一区麻豆| 午夜91福利影院| 女人高潮潮喷娇喘18禁视频| 亚洲七黄色美女视频| 首页视频小说图片口味搜索| 亚洲av片天天在线观看| 亚洲国产看品久久| 精品福利永久在线观看| 成熟少妇高潮喷水视频| a级毛片黄视频| 巨乳人妻的诱惑在线观看| 亚洲国产欧美一区二区综合| 黄色丝袜av网址大全| 亚洲熟女毛片儿| 99热只有精品国产| 中文字幕人妻熟女乱码| 亚洲午夜理论影院| 精品国产一区二区三区四区第35| 啪啪无遮挡十八禁网站| 淫妇啪啪啪对白视频| 日本免费一区二区三区高清不卡 | bbb黄色大片| 国产成人精品久久二区二区免费| 涩涩av久久男人的天堂| 久久久久久久精品吃奶| 伦理电影免费视频| ponron亚洲| 19禁男女啪啪无遮挡网站| 日本一区二区免费在线视频| 超碰成人久久| 午夜免费观看网址| 三级毛片av免费| 老司机深夜福利视频在线观看| 亚洲第一av免费看| 国产精品久久视频播放| 亚洲精品av麻豆狂野| av中文乱码字幕在线| 日本a在线网址| svipshipincom国产片| 亚洲成人免费电影在线观看| 午夜福利在线免费观看网站| 国产激情久久老熟女| 在线观看66精品国产| 在线观看一区二区三区| 99热国产这里只有精品6| 精品国内亚洲2022精品成人| 午夜免费成人在线视频| 国产精品久久视频播放| 久久国产亚洲av麻豆专区| 成人特级黄色片久久久久久久| 中文字幕人妻丝袜一区二区| 精品熟女少妇八av免费久了| 日本免费a在线| 法律面前人人平等表现在哪些方面| 色老头精品视频在线观看| 久久亚洲精品不卡| 99精品久久久久人妻精品| 在线观看免费高清a一片| 新久久久久国产一级毛片| 精品免费久久久久久久清纯| 亚洲精品国产色婷婷电影| 日韩中文字幕欧美一区二区| 欧美激情极品国产一区二区三区| 婷婷丁香在线五月| 国产成人欧美| 日韩av在线大香蕉| av国产精品久久久久影院| 亚洲精品在线观看二区| 黑丝袜美女国产一区| 成熟少妇高潮喷水视频| 一进一出抽搐gif免费好疼 | 精品国产亚洲在线| 丝袜美腿诱惑在线| 91大片在线观看| 亚洲av成人不卡在线观看播放网| 精品国产乱码久久久久久男人| 色综合欧美亚洲国产小说| 午夜两性在线视频| 91av网站免费观看| 国产人伦9x9x在线观看| 91字幕亚洲| 99国产综合亚洲精品| 国产亚洲欧美精品永久| 久久人人97超碰香蕉20202| 国产精品自产拍在线观看55亚洲| 午夜成年电影在线免费观看| 免费在线观看影片大全网站| 免费搜索国产男女视频| 久久 成人 亚洲| 巨乳人妻的诱惑在线观看| 国产色视频综合| 国产成人精品久久二区二区免费| 叶爱在线成人免费视频播放| 亚洲一卡2卡3卡4卡5卡精品中文| 一边摸一边做爽爽视频免费| 一级黄色大片毛片| 超碰成人久久| 怎么达到女性高潮| 9色porny在线观看| 在线国产一区二区在线| 妹子高潮喷水视频| 欧美av亚洲av综合av国产av| 啦啦啦 在线观看视频| 色精品久久人妻99蜜桃| 在线av久久热| 高潮久久久久久久久久久不卡| 国产视频一区二区在线看| 99国产极品粉嫩在线观看| 国产一区二区激情短视频| 一边摸一边抽搐一进一小说| √禁漫天堂资源中文www| 日韩免费高清中文字幕av| 99久久久亚洲精品蜜臀av| 99国产精品免费福利视频| 麻豆av在线久日| 国产成人啪精品午夜网站| 亚洲一区二区三区不卡视频| 三上悠亚av全集在线观看| 琪琪午夜伦伦电影理论片6080| 久久午夜亚洲精品久久| 黑人欧美特级aaaaaa片| 日韩 欧美 亚洲 中文字幕| 后天国语完整版免费观看| 两性午夜刺激爽爽歪歪视频在线观看 | 一边摸一边抽搐一进一出视频| 99国产精品免费福利视频| 性欧美人与动物交配| 久热爱精品视频在线9| 亚洲男人天堂网一区| 97超级碰碰碰精品色视频在线观看| 亚洲精品一卡2卡三卡4卡5卡| videosex国产| 黑人欧美特级aaaaaa片| 三上悠亚av全集在线观看| 五月开心婷婷网| 午夜精品久久久久久毛片777| 亚洲免费av在线视频| 国产精品乱码一区二三区的特点 | 国产成人精品无人区| 精品国产乱子伦一区二区三区| 午夜影院日韩av| 桃红色精品国产亚洲av| 9热在线视频观看99| 亚洲av日韩精品久久久久久密| 国产精品久久电影中文字幕| 国产男靠女视频免费网站| 国产精品偷伦视频观看了| 国产熟女xx| 在线免费观看的www视频| 十分钟在线观看高清视频www| 在线观看免费视频日本深夜| 51午夜福利影视在线观看| 日韩大尺度精品在线看网址 | 亚洲一码二码三码区别大吗| 久久久久久久久中文| 日韩欧美一区视频在线观看| 老司机午夜十八禁免费视频| 精品国产亚洲在线| 又大又爽又粗| 日韩精品中文字幕看吧| 美女高潮到喷水免费观看| 级片在线观看| 国产高清视频在线播放一区| 成人免费观看视频高清| 在线观看日韩欧美| 久久人妻av系列| 看片在线看免费视频| 国产1区2区3区精品| 一级黄色大片毛片| 亚洲熟女毛片儿| 美女大奶头视频| 天天添夜夜摸| 成人黄色视频免费在线看| 国产高清videossex| 亚洲午夜精品一区,二区,三区| av视频免费观看在线观看| 久久亚洲真实| 丰满人妻熟妇乱又伦精品不卡| 欧美日韩精品网址| 国产精品国产av在线观看| 久久99一区二区三区| 亚洲男人的天堂狠狠| 免费av毛片视频| 欧美日韩福利视频一区二区| 激情视频va一区二区三区| 日韩av在线大香蕉| 两性午夜刺激爽爽歪歪视频在线观看 | 免费不卡黄色视频| 妹子高潮喷水视频| 免费看十八禁软件| 在线观看66精品国产| 国产有黄有色有爽视频| 亚洲国产欧美网| 天堂动漫精品| 国产aⅴ精品一区二区三区波| 久久人人精品亚洲av| 女警被强在线播放| 免费在线观看影片大全网站| 国产精品久久视频播放| 欧美国产精品va在线观看不卡| 国产精品日韩av在线免费观看 | 国产亚洲av高清不卡| 久久人妻熟女aⅴ| 日日夜夜操网爽| 亚洲av美国av| 国产高清国产精品国产三级| 久久亚洲精品不卡| 可以免费在线观看a视频的电影网站| 午夜精品国产一区二区电影| 中文欧美无线码| 欧美日韩精品网址| 欧美激情高清一区二区三区| 91在线观看av| 欧美日韩中文字幕国产精品一区二区三区 | 亚洲一区高清亚洲精品| 亚洲国产欧美日韩在线播放| tocl精华| 欧美日韩黄片免| 久久精品91无色码中文字幕| 变态另类成人亚洲欧美熟女 | 99久久综合精品五月天人人| 亚洲自拍偷在线| 操出白浆在线播放| 亚洲欧美日韩另类电影网站| 女性生殖器流出的白浆| 久久草成人影院| 欧美成人午夜精品| 亚洲欧洲精品一区二区精品久久久| 久久精品国产综合久久久| 亚洲精品一区av在线观看| 国产一区在线观看成人免费| 亚洲三区欧美一区| 国产av一区二区精品久久| 母亲3免费完整高清在线观看| 少妇的丰满在线观看| 777久久人妻少妇嫩草av网站| 亚洲精品在线观看二区| 亚洲aⅴ乱码一区二区在线播放 | 亚洲av片天天在线观看| 亚洲国产毛片av蜜桃av| 免费搜索国产男女视频| 亚洲情色 制服丝袜| 国产精品综合久久久久久久免费 | 美女大奶头视频| 亚洲av熟女| 国产av一区在线观看免费| 日本黄色视频三级网站网址| 国产精品一区二区三区四区久久 | 亚洲欧美激情在线| 中文字幕人妻丝袜一区二区| 久久性视频一级片| 18美女黄网站色大片免费观看| 欧美日韩亚洲国产一区二区在线观看| 成人精品一区二区免费| 999精品在线视频| 露出奶头的视频| 亚洲男人的天堂狠狠| 侵犯人妻中文字幕一二三四区| 亚洲第一青青草原| 99久久精品国产亚洲精品| 免费日韩欧美在线观看| 国产在线观看jvid| 中亚洲国语对白在线视频| 精品久久久久久久久久免费视频 | 国产精品香港三级国产av潘金莲| 母亲3免费完整高清在线观看| 黄色怎么调成土黄色| 自线自在国产av| 性色av乱码一区二区三区2| √禁漫天堂资源中文www| 天堂俺去俺来也www色官网| 成人亚洲精品一区在线观看| 女人精品久久久久毛片| 激情在线观看视频在线高清| 国产成人系列免费观看| 久9热在线精品视频| 丝袜美足系列| 亚洲精品久久成人aⅴ小说| 热99re8久久精品国产| 美女国产高潮福利片在线看| 国产亚洲精品久久久久5区| 中文字幕av电影在线播放| 99精品欧美一区二区三区四区| 黄色丝袜av网址大全| 少妇被粗大的猛进出69影院| 国产高清国产精品国产三级| 99热只有精品国产| 怎么达到女性高潮| 成人亚洲精品一区在线观看| 亚洲欧美一区二区三区久久| 亚洲狠狠婷婷综合久久图片| 欧美日韩国产mv在线观看视频| 久久中文字幕人妻熟女| 99国产精品一区二区三区| 久久中文字幕人妻熟女| 在线观看舔阴道视频| 久久人妻福利社区极品人妻图片| 国产免费男女视频| 叶爱在线成人免费视频播放| 又黄又爽又免费观看的视频| 一个人观看的视频www高清免费观看 | 一级毛片女人18水好多| 欧美黑人精品巨大| 色婷婷av一区二区三区视频| 国产一区二区三区视频了| 午夜福利在线免费观看网站| 免费观看精品视频网站| 国产不卡一卡二| 国产单亲对白刺激| 欧美黑人精品巨大| 国产精品 欧美亚洲| 国产不卡一卡二| 免费在线观看亚洲国产| 精品电影一区二区在线| 国产精华一区二区三区| 大型黄色视频在线免费观看| 麻豆av在线久日| 亚洲一区中文字幕在线| 亚洲欧美一区二区三区黑人| 少妇 在线观看| 一边摸一边抽搐一进一小说| 久久国产精品影院| 午夜福利在线观看吧| 亚洲 欧美 日韩 在线 免费| 久久久国产成人免费| a级毛片黄视频| 午夜亚洲福利在线播放| 亚洲色图av天堂| 午夜福利在线观看吧| 午夜两性在线视频| 久久精品亚洲av国产电影网| 国产亚洲精品久久久久久毛片| 中国美女看黄片| 精品少妇一区二区三区视频日本电影| 99国产精品一区二区蜜桃av| 亚洲色图av天堂| 超色免费av| 妹子高潮喷水视频| 中国美女看黄片| 不卡一级毛片| 成人黄色视频免费在线看| 黄色 视频免费看| 热99re8久久精品国产| 男女午夜视频在线观看| 精品午夜福利视频在线观看一区| 91麻豆精品激情在线观看国产 | videosex国产| 国产成+人综合+亚洲专区| 免费搜索国产男女视频| 色老头精品视频在线观看| 日韩av在线大香蕉| 亚洲精品中文字幕在线视频| 99久久国产精品久久久| 波多野结衣av一区二区av| 法律面前人人平等表现在哪些方面| 日本vs欧美在线观看视频| 亚洲专区国产一区二区| 国产免费现黄频在线看| 国产精品一区二区在线不卡| 免费少妇av软件| 久久久久久亚洲精品国产蜜桃av| 超碰97精品在线观看| 一边摸一边抽搐一进一小说| 欧美 亚洲 国产 日韩一| www.999成人在线观看| 一级片'在线观看视频| 91成人精品电影| 国产欧美日韩一区二区精品| 在线观看免费视频日本深夜| 18禁美女被吸乳视频| 免费一级毛片在线播放高清视频 | 美女高潮喷水抽搐中文字幕| 热99re8久久精品国产| 侵犯人妻中文字幕一二三四区| 国产有黄有色有爽视频| 亚洲欧美一区二区三区久久| 国产精品九九99| 精品久久久久久久久久免费视频 | 精品国产一区二区久久| 欧美日韩亚洲高清精品| 嫩草影院精品99| cao死你这个sao货| 黑人操中国人逼视频| 欧美黄色片欧美黄色片| av片东京热男人的天堂| 久久久久久免费高清国产稀缺| 久久中文字幕人妻熟女| 一级毛片精品| 99热只有精品国产| 欧美一级毛片孕妇| 亚洲成人精品中文字幕电影 | 午夜久久久在线观看| 久久天躁狠狠躁夜夜2o2o| 亚洲自偷自拍图片 自拍| 午夜亚洲福利在线播放| 一本大道久久a久久精品| 大陆偷拍与自拍| 日日摸夜夜添夜夜添小说| 99国产精品免费福利视频| www.熟女人妻精品国产| 亚洲自拍偷在线| av片东京热男人的天堂| 99久久人妻综合| 精品久久久久久电影网| 悠悠久久av| 亚洲人成电影免费在线| 12—13女人毛片做爰片一| 制服诱惑二区| 中文亚洲av片在线观看爽| 交换朋友夫妻互换小说| 黑人欧美特级aaaaaa片| 久久精品影院6| 国产伦一二天堂av在线观看| 桃红色精品国产亚洲av| 丰满饥渴人妻一区二区三| 午夜免费激情av| 三上悠亚av全集在线观看| 老司机福利观看| 美女高潮喷水抽搐中文字幕| 91在线观看av| 午夜福利在线观看吧| 久久人人97超碰香蕉20202| 久久久国产成人精品二区 | 久久青草综合色| 香蕉丝袜av| 国产精品国产高清国产av| 又大又爽又粗| 亚洲精品在线观看二区| 精品日产1卡2卡| 1024香蕉在线观看| 亚洲中文日韩欧美视频| 午夜福利在线观看吧| 热99国产精品久久久久久7| 叶爱在线成人免费视频播放| 又黄又粗又硬又大视频| 亚洲av美国av| 久久热在线av| 长腿黑丝高跟| 久久人妻av系列| 亚洲国产毛片av蜜桃av| 可以免费在线观看a视频的电影网站| av中文乱码字幕在线| 免费女性裸体啪啪无遮挡网站| tocl精华| 日日摸夜夜添夜夜添小说| 免费在线观看完整版高清| 丁香六月欧美| 欧美午夜高清在线| 成人影院久久| 老汉色av国产亚洲站长工具| 中文字幕最新亚洲高清| 久久天堂一区二区三区四区| 国产精品一区二区免费欧美| 亚洲av美国av| 精品第一国产精品| 男女床上黄色一级片免费看| 成人18禁在线播放| 国产一卡二卡三卡精品| 91精品国产国语对白视频| 天天添夜夜摸| 亚洲一区中文字幕在线| 一级片免费观看大全| 成年版毛片免费区| 亚洲精品中文字幕一二三四区| 亚洲欧美一区二区三区久久| 一个人免费在线观看的高清视频| 欧美最黄视频在线播放免费 | 亚洲aⅴ乱码一区二区在线播放 | 久久精品国产亚洲av香蕉五月| 午夜成年电影在线免费观看| 一进一出好大好爽视频| 一级毛片女人18水好多| 色综合站精品国产| 欧美日韩国产mv在线观看视频| 国产伦人伦偷精品视频| 热99国产精品久久久久久7| 亚洲一码二码三码区别大吗| 国产精品一区二区精品视频观看| 交换朋友夫妻互换小说| 又紧又爽又黄一区二区| 中文字幕人妻熟女乱码| 乱人伦中国视频| 99热国产这里只有精品6| 999久久久国产精品视频| 亚洲人成伊人成综合网2020| 午夜影院日韩av| www国产在线视频色| 国产又爽黄色视频| 欧美中文综合在线视频| a级片在线免费高清观看视频| 国产精品一区二区免费欧美| 成人免费观看视频高清| 99久久99久久久精品蜜桃| 久久久久久大精品| 亚洲一区二区三区不卡视频| 欧美午夜高清在线| 黄色怎么调成土黄色| 色综合站精品国产| 久久精品亚洲熟妇少妇任你| 久久久久九九精品影院| 黑人巨大精品欧美一区二区mp4| 久久午夜亚洲精品久久| 欧美亚洲日本最大视频资源| 人人妻人人澡人人看| 久久久国产欧美日韩av| 少妇的丰满在线观看| 美女午夜性视频免费| 精品久久久久久成人av| 在线观看一区二区三区| 真人一进一出gif抽搐免费| 激情在线观看视频在线高清| 视频在线观看一区二区三区| 色哟哟哟哟哟哟| 很黄的视频免费| 亚洲精品久久成人aⅴ小说| 制服人妻中文乱码| 19禁男女啪啪无遮挡网站| 国产熟女xx| 国产精品久久视频播放| 国产成人欧美| 两人在一起打扑克的视频| 婷婷六月久久综合丁香| 最近最新中文字幕大全电影3 |