Wind Tunnel Tests of Long Span Half - through Arch Bridge Section Model

Wind induced vibration is one of the main control factors in the Long span bridge structure design. The wind tunnel tests for measuring the static wind forces on the bridge girder and the section model wind tunnel dynamic testing for Caiyuanba Yangtze River Bridge in Chongqing are introduced in this paper. The wind tunnel testing for measuring static wind forces and vortex- induced vibration test on the arch are introduced taking account of the influence between two arches. The main contents and outcomes of testing are presented. It is indicated that the bridge girder has excellent wind stability and the arch mechanical characters are rather complicated. The drag force on the hind arch varied a lot because of the font arch interference on the wind flow. The drag force on the hind arch will be negative when two arches are close to each other. It increases with the space of two arches. The results of testing will give the data of buffeting and vortex - induced vibration and flutter analysis of the bridge.     

Structural Model and Cargo-handling Technology of the Quay with High Amplitude of Water Level in Lantsang

The background of a west communication science & technology project whose topic is structural model and cargo-handling technology of the quay with high amplitude of water level in Lantsang is introduced, and its main research content, research of key technology and main findings are introduced too. Three types of structural model and cargo-handling technology which can be applied perfectly in Lantsang are put forward. The structural models include beam and slab structure with pillar supported, box bridge crane structure and reinforced earth structure, the cargo-handling technologies include vertical fixed crane technology, bridge crane technology and movable simple crane technology. Some findings have been applied in the supporting engineering-Menglun harbor.     

Aerostatic stability analysis of long span half-through arch bridges

The main arch of a long-span arch bridge is a compression member. The static wind loads on the bridge not only causes changes of dynamic characters, but also leads the structure to collapse or buckling. Especially, when the arch bridge has longer span and less lateral braces,its stability is much different from the long span cable-stayed bridges and suspension bridges. This paper takes Chongqing Caiyuanba Yangzi River Bridge as a typical example and conducted the wind section tunnel tests. The displacement response of the bridge is obtained and its yield and static stability mechanism under static wind is analyzed. The results show that those factors, such as initial attack angle of the static wind, material yield strength and the static forces coefficients, have great effects on the aerostatics stability of a long span half-through arch bridge.     

Construction Technology for the Main Bridge Pier of Citong Bridge in Quanzhou City

The Citong Bridge is located in the river estuary section with 4 meter tide range and mixed geological structure. In this paper, the technique for construction of the main bridge pier was presented in detail, which consists of the construction process, technological requirements, main construction parameters and amendment on defects. It is of great value for reference to the similar works.     

Static Load Test and Calculation on Multi-tower Cable-Stayed Bridge with Tie-down Cables

The static load test and the finite element analysis of the multi-tower cable-stayed bridge with tie-down cables are carried out. The test and analysis model of the bridge is created by referencing to the actual structure of a Changjiang River bridge. The static mechanical behaviors of such bridge with tie-down cables and the normal multi-tower cable-stayed bridge are comparatively analyzed by the static load test and the finite element analysis. It is shown that the structural system of the cable-stayed bridge with tie-down cables can effectively improve the structural rigidity and reduce the bending moment of the main beams, pylons and piers. According to the results, the best scheme about the location and number of tie-down cables is proposed.     

Research on Bridge Structure Noise of Railroads and Underground

This paper analyses the generating mechanism of radiation noise which produced by bridge structures and vibro-acoustic characteristics, and reviews the current situation of the researches on the relevant standards of structure noise at house and abroad. The author summarizes the method of measurement and calculation about structural noise at house and abroad, further notes their limits. This paper explores the impact of such factors as rain speed and other different fluids on structure noise. The noise characteristics of structures like cavity structure and thin-slab structure are also discussed. Strategies for reduce the bridge structure noise are summed up by reducing the vibration of track structure, altering the structure of boundary conditions, increasing the stiffness and changing the bridge cross section. Finally it comes to a conclusion that a combination of these strategies is the root way to settle the question of the bridge structure noise.     

DSV型小麦雄性不育系特性的初步研究

研究了一种新型小麦雄性不育系（DSV型雄性不育）,其主茎穗可以结实,分蘖穗不结实。该不育系与普通小麦品种杂交,其F1代具有较高的恢复性,此不育系的不育性与温光并无太大关系。经初步观察,在减数分裂过程中,发现有染色体桥与落后等结构变异现象。由此表明,该雄性不育系的不育性与染色体结构变异有关。     

Cause Analysis and Treatment Measure on Cracks in New Reinforced Concrete Restricted by Old Web Concrete

In this paper, the cause analysis about cracks on the new concrete web poured in multi -span continuous box -girder of a main bridge was introduced. This bridge is a prestressed concrete one with variable cross sections and an 80 -meter main span. When casting reinforced concrete in large volume in box girder during vehicle transport service, the shrinkage cracks in cast -in place reinforced web concrete were formed due to the restriction of old web concrete. Then, the control measure taken on these cracks is discussed.     

Research of Structure Optimization Design for Ten Mile River Landscape Bridge

Guiyang Huaxi district landscape bridge is seven miles the beach driving bearing type reinforced concrete box arch bridge, the design process of conventional arch bridge solutions with less thrust arch bridge to carry on the comparison, the combination of special terrain, geological conditions, finally chose the foundation excavation is small, economical, reasonable structure, less thrust of arch bridge using edge inclined rod and bearing platform consolidation, forming the free cantilever end method better solve the horizontal thrust at arch feet larger, by establishing the structure finite element model, analyzes the static force performance, the results show that the thrust of arch stress performance good, less economically feasible, beautiful appearance, and the scenic spot environment more harmonious.     

Application Study on Optimal Sensor Placement Technique of Cable-stayed Bridge

Based on the modal assurance criterion, using simulated annealing algorithm, the dynamic characteristic data of cable-stayed bridge are extracted, optimal acceleration sensor layout scheme of main beam is obtained. According to this optimization scheme, we carry out a dynamic characteristics test on one cable-stayed bridge. The results between test data and finite element modal calculation are very closely. Theory technique research and field modal test demonstrated that the simulated annealing algorithm based on modal assurance criterion is effective and viable for optimal acceleration sensors placement of cable-stayed bridge.     

Time Domain Analysis on Buffeting of Jinma Bridge

Jinma bridge is a long span cooperative-system cable-stayed bridge with one tower cooperated with T frames on both sides.Owing to artistic form and lying in typhoonprone area,it is essential to process the buffeting analysis.In this paper,the turbulent wind velocity was first simulated with cosine wave superposition method as multi-correlated random processes;then,the time domain expressions for the buffeting and self-excited forces were given.On this basis,the buffeting analysis of Jinma Bridge was made.The results show that the anti-wind capacity of the cooperative-system cable-stayed bridge is ensured although the torsional resistibility of the main girders of this bridge is not good.     

土壤中钙与有机碳之间相互作用的研究进展与展望

土壤是植物赖以生存的物质基础,土壤中有机碳含量的高低决定着土壤肥力大小。为了给植物生长发育提供良好的物质条件,提高土壤有机碳含量很有必要。钙素不仅是植物生长发育所必需的营养元素,而且在对土壤有机碳的固持方面也有着至关重要的作用。所以,了解清楚钙素对土壤中有机碳进行固持的机制是很有必要的。通过查阅近年来国内外相关文献报道,分别详述了钙元素的主要植物生理作用、土壤中的主要存在形态以及钙元素与土壤中有机碳之间的相互作用等方面的研究进展。研究表明,钙与土壤有机碳含量存在显著的正相关关系,交换态和有机结合态钙能够影响SOC的积累与转化。同时,土壤中的矿质（无机）胶体通过钙和铁铝的键桥作用与有机质形成有机无机结合态腐殖质,钙离子可以在有机胶体和矿物表面形成离子桥,增强土壤的团粒结构性。然而,还存在一些土壤钙含量对土壤团聚性无明显影响或负面影响的报道。     

浇筑式钢桥面铺装层推挤变形病害机理分析

以贵州省北盘江大桥钢桥面铺装层推挤变形病害为研究背景,采用凝胶渗透色谱法(GPC)和傅里叶变换红外光谱法(FTIR),从沥青分子尺度分析钢桥面铺装产生推挤变形的原因。分析结果表明:沥青老化并不是造成钢桥面铺装层推挤变形的主要原因;从现场调查可知,第2层粘层粘结能力的降低是造成钢桥面铺装层推挤变形病害的次要原因;通过级配分析发现,造成钢桥面铺装层推挤变形的主要原因是浇筑式沥青混合料(GA)级配偏细以及GA中集料颗粒的棱角性较差所致。     

Spatial Calculation Methods of Three Main Trusses Continuous Plate truss Composite Bridge

According to the structural features of three main trusses continuous plate truss composite bridge, two composite beam methods are presented by constructing the displacement mode of composite beam elements and deriving the stiffness matrix of composite beam elements. The characteristic of composite beam method one is that the bridge slab is taken as the top flange of the chord of main truss and combined with the chord of main truss to form a steel concrete composite beam; the characteristic of composite beam method two is that the bridge slab is taken as the top flange of longitudinal and traverse beam and form a steel concrete composite beam with longitudinal and traverse beams. And as for the conventional plate beam composite method, the slab is characterized by forming bridge slab system with continuous isotropic sheets and longitudinal and traverse beams to bear load. Also, the comparison between theoretical results and experimental ones verifies the effectiveness of the above three methods.     

Analysis of Vehicle-Bridge Coupled Vibrations for Simply Supported Girder Bridge Considering Bridge Surface Roughness

Bridge surface roughness is usually considered to be the main Influencing factors of vehicle-bridge coupled vibrations.The way that obtaine Bridge surface roughness by the transformation of power spectral density is effective and rapid.The Bridge surface roughness is obtained by Fourier inverse transform method and trigonometric series method respectively. It can be concluded from the comparision that the precision of Fourier inverse transform method is higher than trigonometric series method. The vibration functions for 4-dofs Vehicle and bridge were derived with the employment of d'Alembert principle and computational procedures for vehicle-bridge coupled vibration were compiled. The dynamic response of a simply supported beam and vehicle was analyzed considering bridge surface roughness which was obtained by Fourier inverse transform method.The research shows that the influence due to the bridge surface roughness is significiant and vehicle speed also effects the bridge vibrations by changing the frequency of the force acting on the bridge due to vehicle and the force acting on the vehicle due to bridge deformation.     

Dynamic Finite Element Model Updating of Prestressed Concrete Continuous Girder Bridge Based on Real-Coded Accelerating Genetic Algorithm

The dynamic finite element model (FEM) of a prestressed concrete continuous girder bridge (PCCGB), named Zhangjiagang river main bridge, was established and updated based on the results of field ambient modal testing using real-coded accelerating genetic algorithm (RAGA), which objective function was defined based on frequency index and correlation coefficient index for evaluating the updated FEM. The dynamic FEM of the bridge was updated based on seven experimental modal parameters. The prediction ability of the updated FEM were evaluated based on three experimental modal parameters. The updated results and prediction ability of updated FEMs indicated that they can reflect adequately the dynamic characteristics of actual PCCGB by using the above objective function and RAGA.     

Research on Seismic Behavior of Top-bear Arch Bridge with Viscoelastic Damping Braces

This paper proposes a new method of structure control that to set damping braces in a top - bear arch bridge. Lumped damping can be introduced to structures to reduce seismic response. The FEM analysis of Nimu bridge which is braced with viscoelastic dampers had done. The results show that the viscoelastic damping braces can remarkably decrease displacement within the arc plane, which is an efficient structure control method.     

Design method and homogeneity control of bridge fair-faced concrete

According to the structural characteristics of bridge engineering, the mix optimization design method of bridge fair-faced concrete was presented, and C30~C50 concrete with high cohesion and package, outstanding fluidity and excellent mechanical properties were prepared. Through the test of air content of fresh concrete, micro hardness and micro structure in different parts of hardened concrete specimens, effects of viscosity-modifying admixtures on homogeneity of concrete were discussed. The results showed that the composition of bridge fair-faced concrete were relatively homogeneous, and the microstructure were relatively dense. When C30 concrete mixed with 5 × 10 -5 cellulose ether or 6% silica fume (mass fraction of cementitious material), air content of fresh concrete were less than 2%, and slurry viscosity values were between 1 900 and 2 000 MPa·s. Also, the micro hardness values in different parts of hardened concrete specimens were closed. The results were applied in practical bridge engineering, which generally meets the apparent quality requirements of bridge fair faced concrete.     

Fiber Fabry-Perot Sensor and Its Application for Monitoring Bridge Strain

The strain is an important parameter that reflects the bridge health status, the fiber Fabry-Perot sensor is embedded in the concrete structure as the intelligent sensing element for the bridge strain. The strain measuring system is made up of the fiber Fabry-Perot sensor,light switch,fiber strain gauge and the comput- er; it can be used to monitor automatically the bridge strain. At present,the system has been installed in the Dafosi Bridge over the Yangtze River in Chongqing. The monitoring data show that the fiber Fabry-Perot sensor has good stability and reliability; it can be used to monitor the bridge strain for a long time.     

Operational Bridge Responses due to Road Surface Profile Spectral Excitations

Random spectrum excitation samples of a road surface profile are investigated. The displacements, velocities, accelerations of a vehicle and a bridge structure are discussed using certain samples. The road excitations are numerically simulated by the random phase cosine method of the power spectral density. The vehicle bridge system responses are obtained using the vehicle bridge differential equations for different road surface profiles. It is concluded that the random phase has critical effects on the road surface profile curve shape, and the power spectral density on the curve value. The random samples possesses the same statistical characteristics. The system response values are affected more by the road surface profiles, and the response shapes are affected more as the vehicle velocity varies. Some engineering advice is proposed based on the numerical calculation with the different random excitation inputs for their significant differential responses.