提高既有电气化铁路接触网桥钢柱更换的安装效率探讨

既有电气化铁路接触网桥钢柱经过长时间的运行,在一定程度上会设备老化、锈蚀,结合陇海线既有电气化铁路桥钢柱更换设计,阐述了怎样提高既有电气化铁路接触网桥钢柱更换的安装效率。

Q345qC桥钢埋弧自动焊接技术的应用

从Q345qC桥钢的特性入手,详细介绍了Q345qC桥钢埋弧自动焊工艺的特点、焊接材料的选择、焊接质量检验等,为今后Q345qC桥钢的自动埋弧焊总结了经验,创造了较大的经济效益和社会效益。

Design and evaluation of UHPP steel bridge deck pavement for high-temperature and rainy regions

To enhance the serviceability of steel bridge deck pavement(SBDP)in high-temperature and rainy regions,a concept of rigid bottom and flexible top was summarized using engineering practices,which led to the proposal of a three-layer ultra-high-performance pavement(UHPP).The high-temperature rutting resistance and wet-weather skid resistance of UHPP were evaluated through composite structure tests.The internal temperature distribution within the pavement under typical high-temperature conditions was analyzed using a temperature field model.Additionally,a temperature-stress coupling model was employed to investigate the key load positions and stress response characteristics of the UHPP.The results indicate that compared with the traditional guss asphalt+stone mastic asphalt structure,the dynamic stability of the UHPP composite structure can be improved by up to 20.4%.Even under cyclic loading,UHPP still exhibits superior surface skid resistance compared to two traditional SBDPs.The thickness composition of UHPP significantly impacts its rutting resistance and skid resistance.UHPP exhibits relatively low tensile stress but higher shear stress levels,with the highest shear stress occurring between the UHPP and the steel plate.This suggests that the potential risk of damage for UHPP primarily lies within the interlayer of the pavement.Based on engineering examples,introducing interlayer gravel and optimizing the amount of bonding layer are advised to ensure that UHPP possesses sufficient interlayer shear resistance.

Dynamic Characteristics of Long -Span Steel -Concrete CompositeBeam Bridge Based on Vehicle -Bridge Coupling Effect

In order to investigate the effect of vehicle-bridge coupling on the dynamic characteristics of the bridge,a steel-concrete composite beam suspension bridge is taken as the research object,and a three-dimensional spatial model of the bridge and a biaxial vehicle model of the vehicle are established,and then a vehicle-bridge coupling vibration system is constructed on the basis of the Nemak-βmethod,and the impact coefficients of each part of the bridge are obtained under different bridge deck unevenness and vehicle speed.The simulation results show that the bridge deck unevenness has the greatest influence on the vibration response of the bridge,and the bridge impact coefficient increases along with the increase in the level of bridge deck unevenness,and the impact coefficient of the main longitudinal girder and the secondary longitudinal girder achieves the maximum value when the level 4 unevenness is 0.328 and 0.314,respectively;when the vehicle speed is increased,the vibration response of the bridge increases and then decreases,and the impact coefficient of the bridge in the middle of the bridge at a speed of 60 km/h achieves the maximum value of 0.192.

Condition survey and analysis of epoxy asphalt concrete pavement on Second Nanjing Yangtze River Bridge:a ten-year review

To obtain a complete picture of the epoxy asphalt pavement condition on the Second Nanjing Yangtze River Bridge, an on-site survey is conducted to collect information regarding traffic composition and extents of pavement distresses. The survey shows that 30 m2 out of the entire 3.8 × 104 m2 pavement exhibits potholes and alligator cracks. Other surface cracks are also found, including regular longitudinal cracks, short hairline cracks, bubble cracks, and ring cracks. Rutting and shoving are not observed on the pavement. The causes of pavement distresses are discussed by analyzing the pavement mechanical response with actual traffic composition. Research results indicate that the regular longitudinal cracks occurring at ribs near wheelpaths are due to fatigue damage. Short hair cracking and bubble cracking are mainly related to construction defects. Alligator cracks are the results of the development of regular, short hair and bubble cracks lacking effective maintenance. Potholes are induced by the cracking and moisture ingression.

Mechanical properties of epoxy asphalt mixture pavement with lightweight aggregate applied on bascule bridge

The high temperature anti-rutting performance,water stability and low temperature bending property of epoxy asphalt mixture with 0%,15%,25%,40%,and 70% granulated and circular lightweight aggregates by weight are tested,respectively.The dynamic responses under the vehicle load and in the opening process are analyzed to obtain the mechanical responses of pavements by using the finite element method.The complicated structure including a steel deck and a waterproof adhesive layer is made to verify the bond strength of the 2451-type epoxy asphalt binder.Research results show that the epoxy asphalt mixtures with lightweight aggregate replacement percentages from 0% to 70% all satisfy the requirements for steel bridge pavements.The epoxy asphalt mixture with a 70% circular lightweight aggregate replacement percentage is recommended because of its smaller density when compared with other epoxy asphalt mixtures.The shear stress increases with the increase in the opening angle and achieves its maximum at the maximum opening angle of 85°.Test results show that the Tianjin Bascule Bridge can be used for first opening after a 3 d pavement conditioning.

Axle-equivalent method of steel-deck pavement

An index system of steel deck pavement design is proposed according to the study and classification of failure types. Furthermore the axle-equivalent equation is presented according to the fatigue principle of pavement structures. Based on indoor experiments and theoretical analysis, this paper studies the stress characteristics of three different axle types which are corresponding with the other three typical pavement structures, and also presents the parameters of each axle＇s equivalent formula. The three axle types include single-axle single-wheel, single-axle double-wheel and double-axle double-wheel. According to analyses of influential factors such as climate, environment, traffic and stress condition, the developed axle equivalent formula and the parameters modified by the field test data can be applied in the design of a new bridge deck pavement and the assessment of an existing bridge deck pavement.

Dynamic analysis of pavement on long span steel bridge decks

In order to analyze the dynamic response of pavement on long-span steel bridge decks under random dynamic loads, the irregularities of the pavement surface is simulated with the power spectrum density function, and the random load is calculated according to a vehicle vibration equation of vehicle model. The mechanical responses of three different cases are compared by using a transient dynamic analysis method, i. e., under random dynamic load, constant moving load and dead load respectively. The results indicate that the mid-span of two adjacent transversal diaphragms is the worst load position. The maximum vertical displacement and the maximum transversal tensile stress of the pavement are 1.33 times and 1.39 times as much as those when only considering the impact coefficients. This study not only provides a theoretical basis for the mixture design and structural design of pavement, but also puts forward higher demand on the construction and maintenance for steel deck pavement.

Analysis on cracking of deck pavement on Jiangyin Bridge

Based on four-year field inspection and investigation on deck pavement of mastic asphalt on Jiangyin Bridge, cracking causes of mastic asphalt are studied. Cracks of deck pavement are summarized on crack length and width to get a clear view of their propagations. Traffic surveys including traffic volume, axle load and vehicle speed were also conducted to assess their influences. Samples taken on-site were tested with pulling-out test and fatigue test to benchmark their properties. According to the inspection and tests results, it is concluded that the cracks are induced by rutting and fatigue. Lack of fatigue resistance, not well bonded to the steel deck and insufficient high temperature stability are supposed to be the main reasons as well as high density of low speed, excessively overloaded trucks.

Evaluation of modification effect of epoxy resin based on performance of asphalt mixtures

Based on the analysis of the main failures discovered in pavement on steel deck plate and the demanding service condition of the pavement on steel deck, high-temperature rutting test, low-temperature bending test and controlled stress flexural fatigue test are used to study the performance of asphalt mixtures modified by epoxy resin including high-temperature stability, low-temperature cracking-resistance, and fatigue cracking-resistance, which are served to evaluate the modification effect of epoxy resin of different contents. With the addition of epoxy resin, all the three performances are improved greatly. However, when the amount of epoxy resin added is over a certain value, the modification effect will be stable with no extra benefit detected. Finally, in terms of the properties of the three respects, 20%, 30%, 30% are given separately as the proposal adding contents.

Finite element simulation and optimal analysis of surfacing on steel orthotropic bridge deck

To analyze the stress state of steel orthotropic deck pavement and provide reference for the design of the overlay, the inner stress state and strain distribution of surfacing under the load of the deformation of the whole bridge structure and tyre load are analyzed by the finite element method of submodeling. Influence of surfacing modulus on the strain state of the overlay is analyzed for the purpose of the optimal design of the overlay structure. Analysis results show that the deformation of the whole bridge structure has no evident influence on the stress state of the overlay. The key factor of the overlay design is the transverse tensile strain in the overlay above the upper edge of web plate of rib. The stress state of the overlay is influenced evidently by the modulus of rigidity transform overlay. And the stress state of the overlay can be optimized and lowered by increasing the modulus and thickness of rigidity transform overlay, The fatigue test has been done to evaluate the fatigue performance and modulus of different deck pavement materials such as epoxy asphalt, SBS modified asphalt, rosphalt asphalt which can provide reference for deck pavement structure design.

Effects of parameters of asphalt concrete surfacing on mechanical property of paving layer

The important parameters that influence the mechanical property of the pavinglayer on an orthotropic steel bridge deck are the paving layer thickness and modulus of the asphaltconcrete surfacing. Three important indices that control the typical failures of the paving layerare the maximum tensile stress of paving layer, the maximum shear stress between the steel deck andthe paving layer, and the maximum deflection on the paving surface. In this paper, the analyticalmodel of paving systems on orthotropic steel bridge deck is established, and the finite elementmethod is adopted to study the stress and strain of paving system. With the variation of asphaltconcrete modulus in high or low temperature season, the influences of paving layer thickness onthree control indices are researched. The results provide a theoretical basis for the determinationof thickness of the paving layer on the steel bridge deck.

Study on low temperature performance of Gussasphalt on steel decks with hard bitumen

Using a Hamburg wheel-track test device, the resistance to rutting of Gussasphalt is tested and compared. Gussasphalt with hard bitumen has good resistance to rutting. The related resistance abilities to cracking at low temperature of Gussasphalt are tested and compared through flexural experiments and the composite structure fatigue test with temperature dropping. Gussasphalt with high performance polymer modified bitumen has a longer fatigue life and a lower breaking temperature; they can be used in the future surfaces for steel bridge decks in Germany.

Static cyclic-loading test on new type of rigid connection of steel girder and reinforced concrete pier

A new type of rigid connection of steel girder and reinforced concrete pier of a bridge is proposed. The components in rigid connection are installed by high strength bolts on the spot, which are very convenient in construction. The moment from superstructure can be effectively transferred to substructure, and the plates provided for shear transferring can withstand the majority of total horizontal force. With static cyclic loading test, useful experimental data is obtained on the new type of connection of steel superstructure and concrete substructure. As a result, the stress transfer mechanism of the rigid connection can be made clearly and the seismic performance of this structure can also be clarified. Compared computed strength and ductility with actual results, it can be found that this type of connection has good energy absorption capacity in spite of large displacement and no local buckling arises at the locations where stress concentration occurs. Because of doing away with the expensive bearing, this new type of composite structure can be expected to construct a bridge with high seismic resistant capacity thus saving in total construction cost.

绿色施工新技术在机场施工建设中的应用

近年来,为保护环境,减低能耗,节约成本,国家要求大力推行绿色施工技术。绿色施工技术的推广是贯彻科学发展观的重要体现,是国家保护环境的重要举措。文章以桂林两江机场扩建工程为例,浅谈沥青混凝土透水路面、清水混凝土、高强度钢材、断桥钢型材、BIM技术等绿色施工新技术在机场施工建设中的应用。

桥梁钢结构主塔吊装施工控制要点

以都匀至安顺高速公路第6合同段为例,对该工程中的桥梁钢结构主塔吊装施工技术进行研究。主要对钢箱梁安装要点、吊耳选型计算、钢丝绳选型及计算、卸扣选用、吊装临时支墩体系、临时支墩的基础处理、吊车站位地面处理等方面进行了深入研究,望能为同类工程提供借鉴。

48m简支钢桁梁桥安装施工技术

本文介绍了上马相迪A水电站进厂交通桥48m简支钢桁架梁的安装过程,以供类似工程参考。

大跨度倾斜式双拱桥塔定位施工方法

本文介绍了霍山生态新城路网工程PPP项目双湾大桥钢结构倾斜式双拱形斜拉式桥塔定位施工实践,总结了利用双拱斜塔自平衡设计,对拼装后钢箱拱及时安装拉索,完成钢箱拱高空对接、定位、拼装、焊接、合拢,减少塔柱高长悬臂的沉降变形,以维持双拱间宽幅及平衡的施工经验。

Design and laboratory evaluation of fog-sealed chip seal on epoxy asphalt pavement for steel bridge deck

In order to improve the surface performace of epoxy asphalt pavement （EAP） for steel bridge deck, an epoxy asphalt chip seal （ ECS） covered by a cationic emulsified asphalt fog seal （i. e., fog-sealed chip seal） isproposed and a laboratory study is conducted to design and evaluate te fog-sealed chip seal. First, the evaluation indices and methods of te chip seal on steel bridge deck pavement were proposed. Secondly, the worst pavement conditions during te maintenance time were simulated by te small traffic load simulation system MMLS3 and the short-term aging test for minimizing the failure probability of chip seal. Finally, the design parameters of fog-sealed chip seal were determined by the experimental analysis and the performance of the designed fog-sealed chip seal was evaluated in thelaboratory. Results indicate that the proposed simulation method of pavement conditions is effective and the maximal load repetitions on the EAPslab specimen are approximately 925 300 times. Moreover, the designed fog-sealedchip sealcan provide a dense surface with sufficient skid resistance,aggregate-asphalt aahesive performance and interlayer shearing resistance.