bluuebunny/crossref_metadata_2025 huggingface dataset:
A Technique Based on Kalman Filter and Least Square Estimation for Time Domain Structural Damage Detection
Authors: Lei Ying , Mao Yi Ke
Published: December 2010

In this paper, a time domain structural damage detection approach based on Kalman filter and least square estimation is proposed for structures under limited input and output measurements. First of all, the dynamic parameters of the structure, such as stiffness and damping coefficients are identified by sequentially utilizing the extended Kalman estimator and the least squares estimation. Secondly, after the structural dynamic parameters are gained, the normal Kalman filter and least square estimation is used to identify the state vector and unknown input of the structure, and the changes of the structure such as reducing of the stiffness are regarded as ‘additional unknown input’. Then the changed parameters can be calculated by analyses the connection between ‘additional unknown input’ and changing parameters, Local structural damage in the structure can also be detected by tracking the changes in the identified values of structural dynamic parameters in time domain at element level, e.g., the degrading of stiffness parameters. Numerical example of detecting structural local damages in a four story share building illustrates the efficiency of the proposed approach.
Vibration-Based Crack Identification of Generally Supported Beam Structures
Authors: Zhang Yu Xiang , Xu Fu Hou , Wu Cui Qin
Published: December 2010

An effective crack identification method has been developed based on the dynamic behavior of a cracked beam. The nature frequencies of a generally supported beam with crack are calculated by Rayleigh-Ritz method. The crack is then identified from the changes of the nature frequencies caused by the appearance of crack. A hybrid PSO (Particle Swarm Optimization) algorithm is employed as a global search technique to back-calculate the damage. Numerical experiments are carried out on beams with different crack damage. The results demonstrate that the proposed method is able to effectively and reliably locate and quantify the crack in the beam with elastically restraint against translation and rotation.
Safety Assessment for Single-Tower Self-Anchored Suspension Bridge
Authors: Liang Xiao Fei , Fu Ying Chun , Xu Yue
Published: December 2010

Connected with the practical construction and considering Structural properties of single-tower self-anchored suspension bridge, the multi-level safety evaluation model is established according to the main risk factor and weighting rate of risk factor is analyzed by the analytic hierarchy process. A safety assessment method with qualitative analysis and quantitative analysis is proposed based on the grey theory and fuzzy mathematics theory for the practical problem of multi-index comprehensive evaluation, and risk ranking is given.
A Comparison of Artificial Neural Network Learning Algorithms for Vibration-Based Damage Detection
Authors: Lyn Dee Goh , Bakhary Norhisham , Abdul Rahman Azlan , Hisham Ahmad Baderul
Published: December 2010

This paper investigates the performance of Artificial Neural Network (ANN) learning algorithms for vibration-based damage detection. The capabilities of six different learning algorithms in detecting damage are studied and their performances are compared. The algorithms are Levenberg-Marquardt (LM), Resilient Backpropagation (RP), Scaled Conjugate Gradient (SCG), Conjugate Gradient with Powell-Beale Restarts (CGB), Polak-Ribiere Conjugate Gradient (CGP) and Fletcher-Reeves Conjugate Gradient (CGF) algorithms. The performances of these algorithms are assessed based on their generalisation capability in relating the vibration parameters (frequencies and mode shapes) with damage locations and severities under various numbers of input and output variables. The results show that Levenberg-Marquardt algorithm provides the best generalisation performance.
Study on Benchmark Structure Damage Identification Base on Frequency Response Function and Genetic Algorithm
Authors: Zou Wan Jie , Luo Zhen , Zhou Guo En
Published: December 2010

A combined method for the Benchmark structure damage identification base on the frequency response function(FRF) and genetic algorithm(GA) is presented. The reducing factors of element stiffness are used as the optimization variables, and the cross signature assurance criterion (CSAC) of the test FRF and the analysis FRF is used to constructing the optimization object function and the fitness function of the GA. To avoid the weakness of binary encoding, the floating point number encoding is used in the GA. At last, the Benchmark structure established by IASC-ASCE SHM group is caculated by the proposed method, the results show that even if the serious testing noise is considered, the patterns of damage of the Benchmark structure can be identified well. The effectiveness of the presented method is verified.
Effects of Closure Phase on Vertical Density Profile of Fiberboard
Authors: Zhang Yang , Yu Zhi Ming
Published: December 2010

Studying the vertical density profile (VDP) forming progress of fiberboard helps understand and improve the hot-pressing technology. The presented work aims to investigate the effects of coreline temperature and thickness curve on VDP by changing hot-pressing curve and moisture content of mat. In doing so, it was hoped to study the VDP forming progress and manufacture “Steep-Flat” VDP and “Flat” VDP fiberboard. The results indicated that Closure phase of traditional hot-pressing curve failed to alter shape of mat thickness curve which control the shape of VDP. The mat manufactured by traditional hot-pressing curve was “Steep” VDP and could not manufacture “Steep-Flat” VDP and “Flat” VDP; Closure phase of “high-low-high” hot-pressing curve could be separated into rapid compression stage, thickness expansion stage, and second compression stage. The density of surface layer formed at rapid compression stage and decided by first high-pressure. The density gradient between surface layer and core layer formed at thickness expansion stage and decided by expansion time. The density of surface layer formed at rapid compression stage and decided by second high-pressure. The “Steep-Flat” VDP and the “Flat” VDP could manufactured by modulated moisture content of mat, first high-pressure, expansion time, second high-pressure.
Structural Damage Detection with Cross Correlation Function of Vibration Observations
Authors: Lei Jia Yan , Yao Qian Feng , Lei Ying
Published: December 2010

A structural damage identification technique based on cross correlation function analysis of vibration measurements is proposed. An 8-storey steel shear building model has been chosen as the case verification. Structural acceleration responses from neighbouring test points are used to establish damage identification parameters. Experimental analysis shows that the method can achieve quite precise results.
Research on Deformation Monitoring of Large Span Hyperbolic-Paraboloid Composite Torsional Shell
Authors: Deng Hui , Xiao Guang Jian , Cao Yu
Published: December 2010

Long span hyperbolic-paraboloid composite torsional shell is a new type structure. In order to find out actual deformation of the roof during construction, monitoring is carried out based on deformation monitoring scheme that was put forward in this paper, and deformation parameters and characteristic of the roof are obtained. It is proved that the measured deformation values are basically consistent with the simulation calculations, and the results show that the scheme is correct and feasible, meanwhile, all of monitoring results are helpful for future analog calculation, design and construction optimization of similar project.
Theoretical Analysis for Effects on a Base-Isolated High-Rise Building
Authors: Kang Jin Xia , Zhao Long Mao
Published: December 2010

In this paper, three-Dimensional finite element analysis was used for the research of a base-isolated high-rise building. After studying the effects of different structural systems, action of bidirectional earthquake wave, P-Delta effect and acceleration responses on it, some useful conclusions are given as follows: in the same structural systems, the story shears of the isolated structure are one order of magnitude less than those of the non-isolated structure under the action of the same seismic waves; the story displacements of the isolated high-rise frame-shear structure and those of the isolated high-rise shear wall structure are different under the action of the same seismic waves; under the action of different seismic waves, the earthquake responses of the same structural system are quite different; the effects of bidirectional earthquake waves on some components should be considered; P-Delta effect can be ignored in the base-isolated building; and the acceleration responses of the isolated high-rise building are different from those of the non-isolated counterpart. Results show that the technology of base-isolation can be applied to the high-rise building system.
Capillary Absorption of Liquid by Powder Compact and its Application on Preparation of Repeatable Cement Compacts
Authors: Shen Ye Qing , Deng Min
Published: December 2010

Preparation of repeatable cement compacts may contribute to quantitively research of processing, structure and properties of cement materials. Capillary absorption of liquid by powder compact was briefly reviewed. Deviation degree of absorption coefficient (Dac) was designed for evaluation on repeatable preparation of cement compacts. Dry cement was compacted in special moulds. A group of orthogonal experiments were designed to investigate repeatable preparation of the compacts. Results show the most important factor influencing on repeatable preparation is the cavity size of mould. The influence of force and specific surface area of cement is generally below 1.41%. According to optimum scheme for preparation, Dac is 0.00%. Repeatable preparation of cement compacts may provide a new method for quantitatively research of cement materials.
Vibration-Based Damage Identification Method Using Modified Back-Propagation Neural Networks
Authors: Jin Hai , Nan Fei
Published: December 2010

This paper presents a damage detection method using a combination of global (changes in natural frequencies) and local (displacement mode shapes) vibration-based analysis data as input in neural networks for location and severity prediction of structural damage. The necessary features for damage detection have been selected by performing sensitivity analyses. In order to check the robustness of the input used in the analysis and to simulate the numberical errors, artificial random noise has been generated numerically and added to noise-free data during the training of the neural networks. Furthermore, a modified back-propagation neural networks with the dynamic steepest descent (DSD) algorithm as training algorithm is used to improve the training efficiency. With those as basis, the neural networks can assess damage condition (locaiton and severity) with very good accuracy.
The Stress and Strain Concentrations in Curved Beams of Finite Thickness with End Moments
Authors: Zhang Ling Ling , Yang Zheng , Hou Jian , Wang Zhi Qian
Published: December 2010

In this paper, the elastic stress and strain fields in curved beams of finite thickness with end moments are systematically investigated using 3D finite element analysis. For a curved beam of finite thickness, the through-thickness distributions of the stress and strain concentration factors are not uniform and their distributions are different. The radius of curvature and the thickness of the beam have significant effect on the stress and stain concentrations. The relations of the maximum value and the value at the corner root of surface of the stress and strain concentration factors with different thickness for various radius of curvature are respectively obtained.
Finite Element Analysis of Staircase under Earthquake Action
Authors: Su Qi Wang
Published: December 2010

The stair is the vertical transport hinge among stories, it becomes a very important component. the stair is seriously damaged in Wenchuan earthquake, and it failed to perform the role for person escaping in case of emergency. a reinforced concrete frame structure with plate stairs as an example, the finite analysis is used. Calculation result shows that plate stairs have a great influence on earthquake resistant behavior of the structure. Designing without the plate staircase in consideration would lead to structural weakness in some columns and cause seriously damage under earthquake and affect the safety of structure.
Research on the Evaluation of the Tunnel Leakage Classification Based on BP Artificial Network
Authors: Pan Hai Ze , Huang Yuan Chun , Deng Na
Published: December 2010

Tunnel Leakage has been a key issue of the Tunnel Engineering construction and maintenance because of the universality and serious harmfulness. Aiming at the status of tunnel Leakage in our country, this paper identifies the main factor from all kinds of factors. An evaluation indexes system is advanced which consists of 10 factors coming from following four grade indexes, including construction factors, Drainage and Waterproof Methods for Waterproof Tunnel, the situation of Surrounding Rock and groundwater and physical geography. In addition, an evaluation model based on the BP artificial network is designed. Combining with evaluation example, the calculation method is realized by software. The results show that the evaluation method is useful. The method provides a new way to increase the precision of tunnel leakage disease level evaluation.
Comprehensive Evaluation of In-Service RC Flexural Member′s Reliability Based on Attribute Mathematics
Authors: Li Wen Sheng , He Yi Heng
Published: December 2010

When the reliability analysis of in-service RC flexural member is carried on, an expert evaluation or AHP (analytical hierarchy process) for evaluation is commonly used, but human factors are big. This paper presents a comprehensive evaluation method of a existing RC flexural member’s reliability on the basis of attribute mathematics. According to the actual measured values of each index in the evaluation system, using a mathematical method to calculate weight, and build a comprehensive quantitative analysis model. Example analysis shows that this method can effectively identify and finely distinguish the reliability of in-service RC flexural members, which be much more objective and scientific compared with other previous methods.
The Pile Bearing Capacity Analysis Based on ANSYS and Reliability Analysis
Authors: Yan Qing Zhi , Zhang Zhan , Liu Tai Qiang , Wang Yan Hua
Published: December 2010

Based on finite element theory and finite element software ANSYS, this thesis establish three-dimensional pile-soil contact model pile to simulate the pile-soil interaction, analysis the bearing capacity particularity, analysis of different factors on the pile P-S curves. Using ANSYS optimization module Monte Carlo sampling method calculate pile capacity reliability, Simplify the cumbersome process of reliability analysis.
Study on Reliability of Jacket Offshore Platform by Seismic Action Based on ANSYS
Authors: Yan Qing Zhi , Zhang Zhan , Cui Liang , Wang Yan Hua
Published: December 2010

Jacket Offshore Platform is a complex statically indeterminate structure, reliability of which is impacted by many factors, and the earthquake is a main factor. This paper simplify the significant failure mode of Jacket Offshore Platform by standard. Calculate the reliability of Jacket Offshore Platform under the effect of earthquake with the Monte Carlo method based on ANSYS. The result can provide evidence for safety assessment of Jacket Offshore Platform.
Reliability Research of Masonry Column Strengthened with CFRP Based on Monte-Carlo Method
Authors: Li Li , Jiang Hong Yi , Zheng Yi , Yang Yu Lin , Sun Mei Zhu
Published: December 2010

CFRP(Carbon Fiber Reinforced Plastics) reinforced structure, as one kind of new technology, has been applied extensively in concrete structure, and CFRP reinforced masonry structure has been began studying and applied. But reliability research of masonry strengthened with CFRP is less, which restrains applying of CFRP. In the paper, Combined with the theory of reliability and tests, supposed that it is basic random variable that strength of brick and mortar and geometry dimension of members and effect of load, it is established that the stability probabilistic formula of brick column reinforced by CFRP under axial-loading. Its reliability is calculated, by means of Matlab. Under the action of different loads and total loads being constant, it is analyzed that the relationship of index of reliability and ratio of loading effect. Some useful results are gotten. And the result calculated is reasonable and reliable and it may supply engineering personnel with computer basis.
Artificial Bee Colony Algorithm for Reliability Analysis of Engineering Structures
Authors: Li Hao Jin , Li Jun Jie , Kang Fei
Published: December 2010

Artificial bee colony algorithm is a noval optimization method which is inspired by bee colony foraging behavior. Its use in the structure reliability field presents not only the advantage of its facility of implementation, but also the capability to obtain the design point and the failure probability with good accuracy. And by this method, the reliability index of nonlinear and complex limit state function which iteration scheme may fail to converge could be obtained with efficiency. It is demonstrated by four examples that the present method is reliable and accurate in reliability analysis of engineering structures.
Fuzzy Matter-Element Evaluation Method for Reliability Analysis of an Existing Highway Tunnel
Authors: Gong Zheng Xi , Yang Jian Guo
Published: December 2010

Reliability analysis is the premise for reinforcement and maintenance of an existing highway tunnel. In order to understand the structure reliability of an existing highway tunnel, a fuzzy mat-ter-element evaluation method was put forward based on entropy weight according to the fuzzy matter-element analysis method. Firstly, levels of inspection results were regarded as objects of matter-element and composite fuzzy matter-elements were constructed considering such factors and their evaluation indexes as cracks of concrete lining, lining thickness, concrete strength, cavities behind the lining and water leakage conditions. Secondly, reliability evaluation results of the existing tunnel structure were obtained by calculating the relevancy. Lastly, fuzzy matter-element evaluation model was effectively used to evaluate reliability of one highway tunnel structure.
Fractal Characterization of Corroded Surface Profile in Reinforcing Steel Bars
Authors: Xu Yi Dong , Qian Chun Xiang
Published: December 2010

Based on fractal geometry theory and surface roughness characterization technology, this paper presents the fractal characterization of nonuniform corrosion degree of corroded reinforcing steel bars. The surface profile curves of different corroded reinforcing steel bars were obtained and their fractal dimensions were calculated in order to describe the fractal characteristics. As is shown by the results, the surface profile curves of rebar have statistical fractal feature. However, fractal dimension is not sensitive to small changes in profile curves. By combining fractal dimension D with scale parameter C, characteristic profile parameter r* is derived to characterize the surface profile of corroded reinforcing steel bars sensitively, which realized the unity of multi-scale similarity measurement and absolute measurement. The results of this analysis will become the basis for corrosion damage evolution of corroded reinforcing steel bars.
Resistance of Hydrated Cement Paste to Acid Attack and Kinetics Analysis of Corrosion
Authors: Zhao Ming , Zhang Xiong , Zhang Yong Juan
Published: December 2010

The resistance of hydrated cement paste (HCP) to acid attack was investigated. Three groups of blended cementitious materials were designed, binary binder A (cement and slag), ternary binder B (cement, slag and silica fume), and quaternary binder C (polymer modified ternary binder). According to a series of designed experiments, acid resistance of HCP was tested by acid consumption, mass loss and corrosion depth of specimens. In the study, ternary binder B shows superior resistance to acid attack. The advantage of polymer modification is unobvious. Furthermore, the variability of acid corrosion depth d with time t was analyzed specially for the foundation of degradation model. Kinetics equation of acid corrosion was established in form of d=K•tn to predict HCP corrosion depth at specific age, which provides available references for durability analysis and engineering design of concrete structures.
Numerical Simulation Method for Predicting Chloride Concentration Distributing around Reinforcement in Concrete
Authors: Wang Xian Li , Ma Guang Shu , Qi Chun Ling
Published: December 2010

The reinforcement in concrete alters the pathway for chloride transporting and in turn causes the chloride concentration to accumulate faster near the reinforcement closest to the exposed surface. A mass conservation matrix equation under the non-stable diffusion based on the Fick’s second law was derived. Hereby, a numerical simulation method for predicting chloride concentration in concrete was established utilizing the compiled module based on FEA. The validity of the method was verified by the comparison with the analytical results. The proposed method has a wider applicability for predicting the service life of RC structures. And it can be applied flexibly to any complicated section shape of RC members with multi-boundary attacked by chloride and the reinforcement considered simultaneously.
Damage Analysis on a Frame Structure under Repeatedly Blasting Vibration
Authors: Tan Wen Hui , Yu Miao , Zhang Peng Fei
Published: December 2010

Blasting is a conventional technique for mining, but structures adjacent to open pit mines are often damaged by blasting vibration, therefore, durability and safety of these structures are affected. Damage characteristics of a three-floor frame structure on the top of an open pit mine under repeatedly blasting vibration is studied in this paper. The damage model of structural members is made based on the theory of damage mechanics of continuous medium, and an overall damage model of the structure is also established by the method of frequency. The results showed that the Young’s modulus, frequency of the structure decreased as increasing of the blasting times, the damage factors of structural members are bigger than that of the structure; the strength of the structure decreased greatly under repeatedly blasting vibration, the strength of the structure is low. The durability of structures is affected, but the structure will not collapse. The research is helpful for blasting control in open pit mines and design on structures adjacent to open pit mines.
Durability of Ancient Earthen Architecture under Wind Erosion in the Milan Ancient City along the Silk Road of China
Authors: Wang Xiao Dong , Zhang Hu Yuan , Yan Geng Sheng , Pei Qiang Qiang
Published: December 2010

Wind erosion is one of the most familiar and serious diseases to Ancient Earthen Architectures (AEA). As far as the durability of AEA is concerned, most previous researches focus on laboratory test with little on field simulative test. In order to find out actual effect of PS (high mole ratio potassium silicate) in enhancing the durability of AEA under wind erosion, this paper combines laboratory test and field test. In the former part, we treated samples with PS of 7% and 10%, then carried out laboratory tests on water stability and compressive strength, as well as wind tunnel tests on wind erosion durability. In the latter part, we infiltrated the test region with PS of 3%、5% and 7%, and carried out wind erosion test on field. The results indicate that the compressive strength and water stability of PS-treated samples are obviously advanced. In the wind tunnel test, the critical wind speed of untreated and treated samples respectively are 12m/s and 20 m/s. In the field test, the durable time of being eroded increases and the failure depth of test region decreases along with the increase of PS concentration. The surface layer of W starts exfoliating in short time, the eroding styles of W3 and W5 are delves-little piece-large piece and delves-little piece, however, there are only several delves in the W7. Laboratory and field results indicate that the PS can to a large extent change the characters of soil, and the durability of AEA under wind erosion is enhanced along with the increase of PS concentration.
A Study on Risk of Durability Failure for Construction Projects of Tunnels and Underground Projects
Authors: Pan Hong Ke , Zhang Zhong Guo , Yang Lin De
Published: December 2010

Tunnel and underground engineering projects have certain failure risks during construction and operation, including the risk of durability failure to which the study is not enough. In this paper, a whole set of research method for analysis, assessment and calculation on durability risk was proposed on the basis of identification to durability risk factors of large underground concrete structures. That is: this paper provided a method of reliability calculation by establishing failure mode and limit-state-equations according to reliability theory; then, classified and collated various risk factors by taking methods of analytic hierarchy process (AHP) and fault tree analysis (FTA); after that, the quantitative analysis of structural durability was done in accordance with Monte - Carlo (M-C) method. Finally, as an example, for the project of passage across the Yangtze River in Chongming, Shanghai, the above methods were applied to estimate the risk of durability failure of segment component. Effective measures and methods were presented and adopted to enhance the durability capacity of structure according to the results of analysis and assessment.
A Specimen Design of Steel Anchor Box on Arch Pylon of a Cable-Supported Bridge
Authors: Lu Chun Yang , Wu Chong , Su Qing Tian
Published: December 2010

A specimen for a static model test was designed to simulate a steel anchor box on the arch pylon of a cable-supported bridge. In order to reflect mechanical behavior of the prototype of the real structure, appropriate boundary conditions were determined by the comparison of FE analysis results from the real structure and the specimen. The design of the specimen successfully dealt with the difficulties in loading irregular structures. The FE analysis results show: the stress distribution on specimen was in good accordance with the real structure; the specimen can well represent the mechanical behavior of the anchor box on arch pylon.
Study on the Stability of Underground Constructions with Different Locations in Alpine and Gorge Region
Authors: Yong Min , Zhu Wei Shen , Yu Da Jun , Wang Li Ge
Published: December 2010

The reasonable selection of a location for underground structures has a great influence on the stability of surrounding rock masses, especially when the construction is built in the alpine and gorge regions. In general, the higher and steeper the mountains are, the more significant the effect is. In this paper, numerical analysis was carried out to study the stress distribution characters in the mountain with different slope angles of 30 °, 45 ° and 60 °. The results show that, the initial vertical component of stress field can not be directly determined by the buried depth when the slope angle is greater than 30 °. Meanwhile, numerical results indicate that is unfavorable for the structural stability when the underground caverns are constructed in the stress concentration areas of mountains with high slope angle. Moreover, some conclusions and recommendations were proposed for the design of underground constructions.
Failure Probability of Salt Rock Underground Gas Storage Cavern Based on Random Field Model of Material Parameters
Authors: Liu Jian , Song Juan , Zhang Qiang Yong
Published: December 2010

For the safety of salt rock underground gas storage cavern, uncertainties of material parameters and their influence to structure must be considered. In this paper, random field method is used for failure probability analysis of gas storage cavern. Random field model of material parameters is introduced firstly, local average method is used in discretization of random field, then Monte-Carlo stochastic finite element method is used in failure probability calculation. Conclusions can be drawn as follow: Failure probability in middle part of the cavern is higher than that of upside and underside, and failure probability decreases when operation pressure increasing. Middle part of cavern in release process is the most dangerous. Failure probability of cavern computed by random field model and random variable model based on response surface method are campared. It is obviously that failure prabability computed by random field is lower than that of by RSM. As variation coefficient and fluctuation range increasing, failure probability of salt rock cavern will increase.
Stochastic Analysis of Chloride Profiles in Concrete Structures
Authors: Jiang Qiong Ming , Yang Lu Feng , Chen Zheng
Published: December 2010

Chloride attack has been identiﬁed as one of the most important factors initiating the corrosion of reinforcing bars. Chloride penetration into the concrete is generally recognized as a diffusion-controlled process. Material properties of the concrete structures are widely recognized that it is of intrinsic randomness, and it is an urgent task to develop a stochastic analysis method for chloride diffusion. Firstly, a deterministic boundary element method with new time marching scheme is developed and described. The diffusion coefficient is described as the random field and discretized based on the local average theory. In order to conduct a stochastic analysis, combining the Monte-Carlo simulation technique with the proposed BEM, the Monte Carlo stochastic BEM for stochastic analysis is proposed in this paper and used in numerical examples. Stochastic analysises presented in this paper provide basis for the reliability analysis of the durability of the concrete structures.
The Formation of Acicular Ferrite and Mechanical Properties Behaviors in a Low Welding Crack Susceptibility Steel
Authors: Lan Liang Yun , Qiu Chun Lin , Zhao De Wen
Published: December 2010

The nucleation and crystallographic characteristics of acicular ferrite in the as-rolled and tempered steel were investigated by using an optical microscopy (OM), transmission electron microscopy (TEM) and scanning electron microscopy (SEM) equipped with electron backscatter diffraction (EBSD). The results showed that acicular ferrite forms at nucleation sites such as dislocations within austenite grains under the heavy reduction in the austensite non-recrystallization region and accelerated cooling conditions, and the inclusions such as Al2O3•MnS may have promotion effect for the formation of acicular ferrite. Acicular ferrite has high misorientation angle boundaries and a number of sub-boundaries or high density of dislocations inside, which contributes to an excellent combination of high strength and toughness. And the morphology of acicular ferrite does not show obvious change in tempering microstructure due to high temperature thermal stability, which plays an important part in keeping good mechanical properties for tempered specimens.
Study on Neutralization Model for Fly Ash Concrete Subjected to Acid Rain
Authors: Niu Jian Gang , Zhang Bing , Niu Di Tao
Published: December 2010

Based on the theory of diffusion and mass transfer, a theoretical neutralization model for fly ash concrete eroded by acid rain was proposed. The values of the model parameters were studied, and the calculation formula of effective diffusion coefficient DA was established considering both material and environmental aspects. The model was verified by acid rain erosion test results, and the results calculated by the model agree well with test results. The model proposed in this paper can be used to predict neutralization depth of fly ash concrete subjected to acid rain attack.
Experimental Investigation on Shear Behavior Of GFRP-Concrete Hybrid Beams
Authors: Zhao Fei , Feng Peng , Chen Chao He , Lou Wen Juan
Published: December 2010

The present study describes an experimental investigation on shear behavior of GFRP-concrete hybrid beams, consisting of reinforced concrete beams combined with U-shaped glass fiber reinforced polymer pultruded profile constructed as combined tensile reinforcement, permanent formwork and corrosion resistance. A total of six beams were tested, three served as control beams and the remaining were implemented with U-shaped GFRP composites. Test results show that hybrid beam provides significant increase in shear capacity when compared to control RC beam.
A Method of Determining Strengthening Design Ground-Motion Parameters for the Existing Building
Authors: Ma Yu Hong , Zhao Gui Feng , Cui Jie , Tan Ping
Published: December 2010

At present, seismic strengthening design reference period of the existing building is usually equal to 50 years in China, sometime this is uneconomic and unreasonable. In this paper, determining principle of seismic strengthening design reference period for the existing building with different importance is presented. The seismic strengthening design level of the existing building is put forward. After the shape factor of intensity probability distribution function is used to represent the seismic hazard characteristic of different areas, the seismic hazard curve formula of design acceleration Amax and earthquake influence coefficient αmax are deduced according to the seismic hazard curve of intensity. The seismic strengthening design ground motion parameter for the existing building with different importance is researched in detail by use of hazard curve formula of seismic ground motion parameter based on seismic hazard characteristic zone. At last, the method and the calculation step are explained by a calculation example. The result shows that for the existing building with different design reference period, using same design parameter is unreasonable in different seismic hazard characteristic zone, and the method is more scientific than the code method.
The Reinforcement Design of Special Vertical Irregular Steel-Concrete Composite Structure
Authors: Zeng Fan Kui , Hu Chang Ming , Liu Xing Cai
Published: December 2010

A reinforcing method is introduced, concerning the inclined and cantilever features in the structure of the Palms together dagoda in the Famen Monastery and the cracking in the floor slab of 54 meters high. According to the actual situation, the welding of the strengthened metal and the structure on the nodes is difficult to achieve. In order to make some improvement, we use bolt connection run throng the wall body instead of steel belt and steel bone welding, which will make the transmission of the structure more clear, shorten the construction period and ensure the engineering quality effectively. This method can also be used for the reinforcement in concrete structures of large span and tall buildings. Therefore, the discussion of processing technology dealing with the combination of the structural cracks in floor which this article focuses on, has some reference value on similar projects.
Experimental Study on Steel-Concrete Interface Skid Resistance Properties
Authors: Yu Tian Lai , Liu Xing Guo , Zhang Hong Xiang
Published: December 2010

Steel-concrete interface skid resistance properties have been studied by orthogonal test. Three factors are considered, including glue amount, silicon carbide mesh, and amount of silicon carbide. For each factor, five levels are selected. Through comparative analyses of the experiment results for each factor and the combinations of the levels of the factors, the combination with the optimal interface skid resistance was obtained. The friction coefficient with consideration of glue cohesive force was also determined. The research results provide references for structure strengthening using adhered steel plates and external prestressing.
Study on Crack Causes and Strengthening Measures of Large Span PC Continuous Box Girder Bridges
Authors: Peng Wei , Zha Zhi Xiang
Published: December 2010

This template Based on cracks observation and finite element analysis of real engineering projects as well as bridge load test after reinforcement, causes and types of cracks in prestressed concrete box girder bridges and treating measurements are systematically studied. The results obtained from the calculation are presented to demonstrate the effect of sensitive factors, such as arrangement of longitudinal prestressed tendons, the magnitude of vertical prestressed force, temperature gradient, etc. The results show that the arrangement of longitudinal prestressed tendons and the magnitude of vertical prestressed force take key roles in cracks control of box girder webs. Lots of treating measurements are presented in accordance with different types of cracks, some of them are applied to a reinforcement engineering of a long span pretressed concrete continuous box girder bridge with cracks. Load test after reinforcement of the bridge demonstrates the reasonability of the treating measurements. Several design recommendations and construction measures about reinforcements and some sensitive factors mentioned above are proposed to control cracks.
Properties of Interface Structure between Ultra-Thin White Topping and Old Concrete Pavement
Authors: Zhao Fang Ran , Wang Shu Fang
Published: December 2010

The research of this paper focused on bond characteristics of overlay-substrate interface in ultra-thin white topping(UTW), aim at ultra-thin concrete overlay on old concrete. Compressive and shear stress have been considered in the structural analysis and experimental research. Bonding behaviors of several surface pretreatments to old concrete have been investigated. A shear-peel test device has been developed to imitate brake-load of wheels at the plate boundary of UTW, and its analytical calculate principle have been discussed to simulate the mechanical theory of the shear peel test. Structural analysis and experimental research results indicate that various flaws are accumulated remarkably in the transition layer at overlay-substrate interface in UTW. Different surface pretreatments of the old concrete will influence on the bonding characteristics of overlay-substrate interface, chiseling treatment for interface has more contribution to working together with the new concrete, but interface adhesive agent enhances the coordination between the interface and the old concrete layer. The treatment combination of chiseling and brushing interface adhesive can effectively improve the strength of the weak interface transition layer. Shear-peel test results indicate that the interlocking influence generated by chiseling treatment is prior to brushing interface adhesive. It is necessary turn to account suitable measure to prevent ultra-thin concrete overlay peeling off from old concrete.
Anti-Seismic Energy Dissipation of Structures with Stress-Dependent Complex Damping with Consideration of Zero Amplitude Damping
Authors: Zhang Hui Dong , Wang Yuan Feng
Published: December 2010

Under most cases, the non-liner energy dissipation is approximately replaced with Rayleigh damping model which belongs to Maxwell-Kelvin type, the method is a fuzzy evaluation method of damping. Based on complex damping theory, equivalent dynamics equation of complex damping model is derived and loss factor is discussed, the accuracy of the equation is theoretically confirmed in this paper. Based on the existing damping theories, a new damping model is proposed, which is a zero amplitude damping model combing with stress dependent complex damping model. The model is used in seismic resistance analysis. Taking a steel beam for an example, the relationship between response amplitude and damping ratio is analyzed with the new damping model. It shows that the method of stress-dependent damping with consideration of zero amplitude damping can precisely describe the energy input and energy dissipation principles and the dynamic response under seismic loads can be precisely obtained. A solid foundation is laid for the further study of complex damping theory, its equivalent viscous damping model and engineering application.
Effect of Cycle-Counting Methods on Fatigue Evaluation of Railway Bridges
Authors: Wang Chung Sheng , Hao Long
Published: December 2010

The effective stress range (ESR) and the number of stress cycles (NSC) are two key parameters in fatigue damage evaluation. The inaccuracies in predicting remaining fatigue life can be attributed to either one of these two parameters. A sensitivity analysis is described to address the effects of four cycle-counting methods on ESR and NSC for various fatigue details, which including rain-flow counting (RF), mean-crossing-peak counting (MCP), level-crossing counting (LC) and simple-range counting (SR). Using field monitoring data under normal traffic of Wei River Bridge, the comparative results of four methods showed that RF was more conservative than MCP and SR. The relationships between RF and other three counting methods were determined in the form of a correlation coefficient and a linear regression line. Therefore, values obtained for ESR and NSC by MCP, LC and SR can be converted to values for RF, which is used for comparison and transformation of fatigue life evaluation results using different cycle-counting methods.
Vibration Analysis and Evaluation of the Indoor Spiral Steel Stair
Authors: Zhou Bin , Ren Xiao Song , Lu Xi Lin
Published: December 2010

The spiral steel stair is widespread used as indoor stair for its graceful appearance. For the space structure system of the spiral stair, it is necessary to make vibration analysis and comfort evaluation to the stair. The load model of pedestrian and the analysis condition by walking and running in the process of ascending and descending are presented in this paper. Referring to some design code and research achievement of footbridge and floor, the index of comfort evaluation, which are the natural frequency, the peak vertical acceleration and the weighted root-mean-square (r.m.s) acceleration, are put forward in this paper. Finally, the numerical analysis and the vibration site test of a practical project are made and the results of vibration analysis and comfortability evaluation are presented to demonstrate the suggestion by the authors.
Flexural Behavior and Ductility of Concrete Beams Strengthened with Near-Surface Mounted GFRP Bars
Authors: Zhang Hai Xia , Wang Ling , Liu Guo Rui
Published: December 2010

The objective of this study is to investigate the flexural behaviors and ductility of reinforced concrete beam with near-surface mounted (NSM) GFRP bars. A total of 5, simply supported rectangular cross-section beams strengthened with NSM GFRP bars and two control beams are tested in this paper. The mode of failure, load-deflection relationship, strain distributions along the height of the beam on mid-span cross-section, and ductility of the beams are analyzed. The studies indicate that the yield and ultimate load have a significant increase compared with the control specimen. Especially, the ultimate load has a more measurable improvement than the yield load. The strain distribution along the height of specimen shows a clear nonlinear characteristic as a result of the crack propagating and steel yield. Also, the studies show that GFRP bars has played an important role in the flexural capacity of the strengthened beam during the stage from the yield to the failure of the beam. Besides, the strengthened beam is considered to be ductile using the displacement ductility index.
On the Soil-Structure Interaction Numerical Study of Strengthening Design of Sluice within Mining Subsidence Areas
Authors: Chang Hong , Xia Jun Wu , Chang Hong Fei , Zhang Feng Jie
Published: December 2010

Finite element models, established using ANSYS, given the soil - structure interaction phenomena produced at the interface between the reinforced concrete structure and the soil, have been used to perform a parametric study of the strengthening design of the foundation and the sluice chamber within mining subsidence area. High pressure jet grouting pile is adopted to reinforce the foundation, this analysis model is simplified by the transformation from the pile foundation to the solid foundation, which reflects the characteristic of pile foundation. The strengthening design of the sluice chamber is a renovation from open style to frame, to increase the integral property. It is indicated that, using high pressure jet grouting pile to reinforce the foundation can apparently improve the stability of sluice in mining area. Nevertheless, it can't improve the stability of sluice through reinforcing the sluice chamber.
Numerical Analysis on Settlement Law of an Underpinning Structure Composed of Piles and Beams
Authors: Jia Qiang , Gu Fang
Published: December 2010

The settlement law during the underpinning process of a frame structure was analysed using the three-dimensional finite element model based on ANSYS program. The birth and death technique was adopted to simulate the work state of the underpinning structure and the underpinned piles. The secondary settlement deformations in the process of foundation underpinning can be simulated when the settlement values of the column bases before underpinning were applied to the underpinning structure. The settlement-location curves of the frame column bases before and after underpinning can be gained through path operation. The analysis results show that the settlement values and the differential settlements of the underpinning location increase obviously after underpinning, the medial deflection of the underpinning beam increases, and the settlement value of corresponding frame becomes bigger. The deformation of the underpinning beam occupys big proportion in the total settlement deformation. When the length diminishes and the diameter augments of the underpinning pile, the stiffness of the pile increases, therefore the settlement values and the differential settlements decrease. When the span diminishes and the height augments of the underpinning beam, the stiffness of the beam increases, accordingly the settlement values and the differential settlements decrease obviously. The width change of the underpinning beam has little influence on the settlement values and the differential settlements.
Interface Properties of Cracked RC Beams Strengthened with Prestressed Hybrid FRP - Part I: Crack Height
Authors: Guo Yong Chang , Xie J.H.
Published: December 2010

This study is the first part of investigation into the interfacial mechanics performances of cracked reinforced concrete (RC) beam strengthened with prestressed hybrid fiber reinforced polymer (HFRP). Finite element (FE) analysis models were established for such beams with different concrete crack height in this paper. The analysis results indicate that the existing of the flexural cracks obviously affect the stress distribution in the interface between concrete and HFRP, and a sudden change of the stress would arise at the cracks. For cracked RC beams strengthened with prestressed HFRP, both the shearing stress and normal stress of the adhesive layer and fiber sheet are much larger than those without cracks, and the growth rate increases with the crack height.