bluuebunny/crossref_metadata_2025 huggingface dataset:
Constructing Surrogate Models for Springback in U-Bending Process
Authors: Bekar Deniz , Acar Erdem , Ozer Firat , Güler Mehmet Ali
Published: February 2012

In this study, surrogate models are constructed to approximate the behavior of simulation models for springback angles, sidewall curl, and sheet thickness reduction in U-bending process. The surrogate-modeling techniques used here are: (i) polynomial response surface (PRS), (ii) Kriging (KR) and (iii) radial basis functions (RBF). While constructing surrogate models, the following procedure is pursued. First, a set of training points is generated using Latin hypercube sampling method, and finite element simulations are performed at these points. Then, surrogate models are constructed utilizing the training data. The accuracies of the surrogate models are evaluated by using the leave-one-out cross validation errors. First-order PRS is found to be most accurate surrogate model for prediction of the springback angles, side wall curl, and sheet thickness reduction.
In Situ Temperature Measurement in the Shearing Zone during Sheet Metal Blanking
Authors: Demmel Peter , Hirsch Martin , Golle Roland , Hoffmann Hartmut
Published: February 2012

Blanking is one of the most widely used manufacturing technologies in sheet metalprocessing, because nearly each sheet must be trimmed out of a semi-finished part or has to beblanked after a forming process to get the precast part in the manufacturing chain. In general, a highquantity of blanked parts should be manufactured without reworking the tool. Therefore a capableprocess is indispensable to avoid inadequate part quality or premature failure of the tool because ofwear. The blanking process is affected by tool parameters, the press and the material properties ofthe blanked part.However, another important factor is the occurring temperature in the shearing zone of the sheetmetal due to the dissipation of nearly 95% of the plastic work during blanking and, in addition,frictional heating. This temperature impacts the blanking process features such as tool-wear andresulting cut edge quality. It has been presumed to be negligible by a lot of authors yet. In contrastsome publications with experimental and analytical research assume that the temperature reachesvalues up to 1000°C. Therefore, this report outlines a thermoelectric method to measure theresulting temperature distribution during the blanking process on the cutting edge of the blankingpunch. The feasibility of the investigated measurement concept is shown on a concrete example.
Simulation of Ceramic Powder Injection Moulding Based on the Behavior of Flow Stress Depended on the Thermal Viscosity Flowage Property and the Volume Fraction
Authors: Lee Moon Kyu , Kim Hong Lae , Hong Seok Moo , Choi Sun Chul , Kim Nak Soo
Published: February 2012

The prediction of flow pattern and volume fraction distribution in ceramic powder injection moulding (CIM) is very important because their characteristics affect the mechanical stiffness and the sintering shrinkage. The definition of feedstock behavior in the simulation of CIM depends on the various parameters such as temperature, strain rate and volume fraction. The aim of this study is to generate the governing equation based on non-newtonian flow model and predict the distribution of volume fraction from the result of CIM simulation using the subroutine of finite element package. Material parameters of governing equation are obtained from the compressive test of feedstock. Initial volume fraction is defined as the value of 0.5 referred to experimental data. In the boundary condition, the velocity of injection is 3 mm/s and the frictional coefficient between the feedstock material and the die is assumed as the value of 0.7 which means the value in the condition of cold moulding. The flow pattern of feedstock is very consistent with the experimental result. The result indicates that the range of volume fraction is from 0.42 to 0.58 depended on the pressure distribution. This result aids to predict the material stiffness according to the location of product from the relationship of the volume fraction and stiffness via Micro-hardness test.
Drawing of Piezoceramic Fibers and Ribbons Using a Novel Alginate Gelation Method and Properties of Fiber and Ribbon-Based Piezodevices
Authors: Alkoy Sedat , Tekdas A. Serkan , Tekel Emre , Olukkent Recep
Published: February 2012

Piezoceramics are usually shaped into three dimensional bulk form using dry pressing or slip casting methods. However, certain applications require piezoceramics to be shaped in one dimensional fiber or two dimensional ribbon form. In this study, piezoceramic fibers and curved piezoceramic ribbons were fabricated using a novel alginate gelation method. Alginate is a natural linear polymer that is obtained from brown kelp. In the presence of multivalent cations, it forms ionic cross-links and gels in a three dimensional network form. In our study, gelation conditions of alginate containing aqueous slips of lead zirconate titanate based piezoelectric ceramic powders were investigated. Piezoelectric ceramic fibers and ceramic ribbons were prepared by sintering of gelled powders for transducer applications. Structural characteristics of these ceramics and electrical characteristics of piezodevices prepared from these ceramics were investigated and reported.
Investigations on the Microstructure and the Fracture Surface of Pulsed Nd: YAG Laser Welding of AISI 304 Stainless Steel
Authors: Akbari Mousavi Seyed Ali Asghar , Garehdaghi A.
Published: February 2012

The paper presents pulsed Nd:YAG laser welding of the 304 stainless steels. The welding tests were carried out with various operational parameters. The effects of laser welding variables on the geometry, microstructure and solidification of the weld are considered. The austenitic or ferritic solidification is produced in the 304 austenitic stainless steel depended upon the cooling rate and its chemical compositions. The possiblity of austenitic solidification compared with the ferritic solidification decreases with the chromium to nickel equivalent ratio and that increases with cooling rates. Moreover, more δ ferrite is obtained if the cooling rate is increased or the higher power laser is used. The surface of fracture samples was considered and the reason for failure was investigated. The study shows that the fracture is in ductile type.
Shape Evolution of Pinholes in Bloom with Multi-Scale Finite Element Technique
Authors: Son Il Heon , Lee Kyung Hoon
Published: February 2012

This study investigates the shape evolution of the pinholes on the bloom surfaces, which are originated from the continuous casting process, during multi-pass hot bar rolling. It is important to track the shape evolution of the pinholes since they can be formed as the sharp surface cracks after hot bar rolling and can initiate the surface bursts in the cold forging process. It is very hard to track the deformation behavior of the pinholes with detection tools during hot rolling, so the numerical simulations can be properly utilized. In general, the size of the pinholes in the bloom surface is order of micrometer although the bloom size is order of millimeter. This size discrepancy between them makes it difficult to discretize the domain including the pinholes for the finite element (FE) simulations. To overcome this limitation of the conventional FE simulation, multi-scale technique coupling the macro and micro models was developed in current study. This technique was implemented into the commercial simulation code, DEFORM-3D. The developed multi-scale simulation technique was capable of simulating the shape evolution of the pinholes through multi-pass hot bar rolling successfully. It is concluded that aspect ratio of the initial pinhole should be larger than 2.0 approximately to prevent it folded.
Manufacturing of Thin-Shell Offset Demonstrator Reflector
Authors: Soykasap Omer , Karakaya Şükrü , Türkmen Durmus
Published: February 2012

This paper presents manufacturing and testing of a 1/3-scaled demonstrator of a full-scale thin-shell reflector. The demonstrator reflector is an offset reflector with a diameter of 2 m, and a focal length of 1.6 m, and an offset distance of 0.1 m. The reflector structure is a simple monolithic structure, and consists of a reflector surface and a skirt. The skirt is an integral part of the reflector and used to stiffen the reflector. The demonstrator is made of plain-woven carbon/epoxy by vacuum assisted resin infusion process. It is aimed that the manufactured reflector has a low manufacturing cost, a high precision surface, and demonstrates capability of folding and deploying.
Investigation of the Improvements on Mechanical Properties and Thermal Performance of MgO-MgAl2O4 Composite Refractories by Additions of ZnO-Al2O3 to MgO
Authors: Aksel Cemail
Published: February 2012

The variations and developments with the reasons on the mechanical properties of MgO-MgAl2O4 and MgO-ZnO-Al2O3 composite refractories were examined and thermal parameters affecting the durability of composites at high temperatures were investigated. The density, porosity, strength, modulus of elasticity, fracture toughness, fracture surface energy, critical defect size and mean MgO grain size values of composites were measured/calculated and evaluated. In addition, microstructural changes using XRD measurements and SEM analysis were examined. Thermal stress/shock parameters R and Rst that are used for determining high temperature performance of composites were calculated. The relationships between mechanical properties and structural variations for different compositions and the factors affecting this connection were investigated. With the additions of various amounts of ZnO-Al2O3 to MgO, significant improvements were achieved on both mechanical properties and R-Rst parameters of in-situ formed M-S-ZnAl2O4 composite refractories, compared to MgO-MgAl2O4 materials containing preformed spinel, by factors of up to 3.6 and 2.0, respectively. The important parameters increasing mechanical properties and thermal performance of M-S-ZnAl2O4 composites were determined as follows: i) formation of ZnAl2O4 phase leading to a high resistance to crack initiation and propagation, ii) propagation of microcracks formed in the structure for a short distance by interlinking to each other, iii) arresting or deviation of microcracks when reaching pores or ZnAl2O4 particles, and additionally iv) co-presence of both intergranular and transgranular types of cracks on fracture surfaces, and with the incorporations of ZnO-Al2O3, v) increase in density, vi) rise in critical defect size, and vii) a significant reduction in MgO grain size. The optimisation of M-S-ZnAl2O4 composite refractories that could be used for obtaining longer service life in industrial applications was performed.
Wear Assessment of Ti/SiC Surface Nano-Composite Layer and its Associated CP-Ti Substrate
Authors: Shamsipur Ali , Kashani-Bozorg Seyed Farshid , Zarei-Hanzaki Abbass
Published: February 2012

In the present investigation, the surface of a commercially pure titanium (CP-Ti) substrate was modified to Ti/SiC nanocomposite layer employing friction stir processing technique; nanosized SiC powder was introduced into the stir zone provided by a rotating and advancing tool. The fabricated nanocomposite surface layer exhibited a micro hardness value of ~535HV which is much greater than 160HV of the substrate material using Vickers micro hardness testing. In addition, the un-treated CP-Ti substrate showed sever wear regime in the pin-on-disc test against the hardened AISI 52100 steel. It suffers extensive typical adhesive wear dominated by plastic deformation as evidenced by scanning electron microscopy. Also, deep grooves were formed, i.e. evidence of abrasive wear. Contrary to this, enhanced wear properties were detected for the Ti/SiC nanocomposite surface layer, i.e. lower coefficient of friction and weight loss. The nanocomposite surface layer was found to be adherent to the underlying substrate during the pin-on-disc test. The superior wear behavior of the nanocomposite surface layer is attributed to its improved micro hardness value due to the presence of hard nanosize SiC particles in a refined titanium matrix.
Permeability of Rapid Prototyped Artificial Bone Scaffold Structures
Authors: Lipowiecki Marcin , Ryvolova Marketa , Tottosi Akos , Naher Sumsun , Brabazon Dermot
Published: February 2012

Fluid flow through a bone scaffold structure is an important factor in its ability to build up a living tissue. Permeability is often used as a measure of a structure’s ability to allow for flow of nutrients and waste products related to the growth of new tissue. These structures also need to meet conflicting mechanical strength requirements to allow for load bearing. In this work, the effect of different bone structure morphologies on permeability were examined both numerically and experimentally. Cubic and hexagonal based three dimensional scaffold structures were produced via stereolithography and 3D printing techniques. In particular, porosity percentage, pore size, and pore geometry were examined. Porosity content was varied from 30% to 70% and pore size from 0.34 mm to 3 mm. An adapted Kozeny-Carmen numerical method was applied for calculation of permeability through these structures and an experimental validation of these results was performed via a standard permeability experimental testing set-up. From the results it was determined that increased permeability was provided with the cubic rather than hexagonal structure as well as by utilizing the larger pore size and higher levels of porosity. Stereolithography was found to be the better processing technique, not only for improved micrometer scale dimensional accuracy reasons, but also due to the increase wettability found on the produced surfaces. The appropriate model constants determined in this work will allow for analysis of new alternate structure designs on the permeability of rapid prototyped synthetic bone structures.
A Study on the Development of Dedicated FEA Tool for Roll Forming of Asymmetrical U-Channel
Authors: Cha Wan Gi , Kim Hong Lae , Kim Nak Soo
Published: February 2012

In a roll forming process, a desired profile is produced through continuous bending of a sheet metal strip. Occurrences of spring back, twist, and bow are major defects in roll formed profiles. We developed a dedicated analysis program based on the elastic-plastic finite element method to simulate roll forming processes with asymmetrical shaped rolls. We applied the augmented Lagrangian technique in contact algorithm and a pre-determined deformation region division method for computation efficiency. A simplified cross section produced via three passes of roll forming has been experimented to be measured in the amounts of twist and bow occurred after roll forming. The performance of the developed FEA tool has been verified with measurements in terms of accuracy. The tool has been evaluated in terms of computation efficiency by comparison of without region division method.
Effect of Tool Material and Offset on Friction Stir Welding of Al Alloy to Carbon Steel
Authors: Karimi Namdar , Nourouzi S. , Shakeri Mohsen , Habibnia M. , Dehghani A.
Published: February 2012

In this research, effect of tool material and tool offset on tool erosion and metallurgical and mechanical properties of dissimilar friction stir welding of Al alloy to carbon steel are investigated. As the tool erosion is one of the important parameters on the defect-free friction stir welding, especially in butt joint of Al alloy to steel. In present work, different tool material and offset are used in friction stir welding at Al alloy to carbon steel with a constant tool speed and feed rate named as 710 rpm and 28 mm/min respectively. The result of experimental observation is shown better performance by tungsten carbide (WC) tool material with 1 mm offset on Al alloy area.
Vibration Drilling Process on Al2024
Authors: Amini Saeed , Tehrani Alireza Fadaei , Barani A. , Paktinat H.
Published: February 2012

Vibration Drilling (VD) is one of the advance machining techniques to produce precision holes. In this study the vibration tool of drilling process is made with a new design while drilling tool vibrates by an ultrasonic transducer, it also rotates. The exerted vibration to tool has frequency of 20.6 kHz and low peak-to-peak amplitude. After preparation of process set-up, primary experiments were done on Al2024 workpiece. In these experiments , it was shown that thrust force in vibration drilling process is lower than in ordinary drilling (OD).Then the influence of some machining parameters include cutting speed and feed rate on thrust force in VD process studied and compared with OD process.
Arc Spraying of Nanostructured Wires on Steel Surfaces: Influence of Coating Thickness on Microstructure and Fracture Toughness
Authors: Askandarani A. , Hashmi M.S.J. , Yilbas Bekir Sami
Published: February 2012

nanostructured coating materials become demanding, since it improves the mechanical properties, such as hardness, through grain refinement. One of the methods of producing nanostructured coatings is to use an arc spray coating process using nanostructured wires. Although the arc spraying process is well developed, the influence of nanoparticles on the fracture toughness of the coating surface has not been examined in details. Consequently, in the present study, arc spraying of nanostructured wires on carbon steel surface is carried out. The influence of coating thickness on the microstructure and fracture toughness of the coating is investigated. It is found that the self-annealing due to large coating thicknesses has a noticeable effect on the microstructure and fracture toughness.
Investigation Using Simulations for the Development of Low Cost Catalytic Converter from Non-Precious Metals
Authors: Mohiuddin A.K.M. , Rahman Ataur
Published: February 2012

This paper discusses the uses of non-precious metals in catalytic converters to bring down the cost without sacrificing the performance capability. Copper powder and nickel catalyst were chosen as the alternative catalysts to reduce the use of precious group metals (PGMs) platinum, palladium, and rhodium. Simulation by COMSOL has shown that Nickel and copper were very effective in reducing NOx during rich condition of air-fuel mixture while oxidizing CO and HC during lean condition. Simulations using FLUENT and COMSOL have shown the actual characteristics of the catalytic converter performance. The flow throughout catalytic converter and the backpressure have successfully determined. Furthermore, catalyst conversion efficiency also has been shown clearly. On the other hands, the experimental results have excellently validated the simulation results in terms of the nature and trends of the catalytic converter performance as well as its efficiency. Catalyst distribution and application of the non-zoning monolith substrates have further contributes to cut down the production cost. It was found that the low cost catalytic converter was able to meet the EURO 2 emission regulation control and has optimum backpressure at full throttle.
Detecting Impact Damages in an Aramid/Glass Fiber Reinforced Hybrid Composite with Micro Tomography
Authors: Fidan Sinan , Sınmazcelik Tamer , Avcu Egemen , Bora Mustafa Ozgur , Coban Onur
Published: February 2012

This paper utilizes the micro computerized tomography (micro-CT) as the NDI technique to characterize the initial matrix delaminations locations and sizes in an aramid/glass fiber reinforced hybrid composite test specimen after a low velocity impact tests. Further, to visualize the localized low velocity impact damage volumes; based on the specimens micro-CT results; image analysis, geometric modeling and meshing softwares CtAn and CtVox were used. Finally, interpretation of damage mechanisms occurred in aramid/glass fiber reinforced hybrid composite after low velocity impact loading presented with accurate 3-D rendered models obtained from a series of micro-CT slices. 3-D rendered models gained from impacted specimens help to quantify the internal microscopic damage modes of complex material system such as aramid/glass fiber reinforced hybrid composite. It is very important to predict or determine composite materials response to an impact loading since impacts occur during manufacture, normal operations, maintenance, etc. After low velocity impact loading tests, investigation of damage zone will provide a better composite manufacturing process. For example, it is acknowledged that up to 80% of the cost of manufacture of a composite is xed once the preliminary conguration had been nalised. Further detail changes afterwards can only make a small impact on the nal cost of the manufacturing process.
The Influence of Concrete Creep on Deflection of Box Beam with Sectional Joints in Continuous Rigid Frame Bridge
Authors: Wang Rong Xia , Li Fan , Guo Rong , Zhao Shao Wei
Published: February 2012

Over-deflection of beam in continuous rigid frame bridge has become an serious problem in recent years. The reason is complex. Some reseachers think that the bad quality of sectional joints in cantilever construction will cause additional shearing deformation and affect the beam deflection, this idea need to be further studied. In the paper, two three-dimensional models are built up based on a factual bridge, the simulation method of sectinoal joints is studied. The influence of concrete creep on the deflection of box beam with sectional joints is analysed being compared to beam without sectional joints . In order to simulate concrete creep, a method of effective elastic modulus adjusted with concrete age was applied. The study shows that the shearing deformation of sectional joints has obvious influence on the long-term deflection , and different calcultion method of concrete creep has different effect on it. It shouldn’t be ignored in the bridge design.
Study on the Properties of Fiber Reinforced Sulphoaluminate Cement Mortar
Authors: Ye Zheng Mao , Wu Qin Yi , Du Peng , Cheng Xin
Published: February 2012

The effects of wood fiber and polypropylene fiber on the mechanical performance, drying shrinkage and moisture loss of sulphoaluminate cement (SAC) mortar were studied. The experimental results show that wood fiber and polypropylene fiber can both improve the flexural strength of the mortar and reduce drying shrinkage ratio and moisture loss at different ages. Polypropylene fiber can also improve the late compressive strength of the mortar. Adding 0.3% mass fraction of wood fiber, the drying shrinkage ratio and moisture loss of the motar reach minimum values. The drying shrinkage ratio reduces to 0.029% at 28d. Moisture loss reduces to 0.4%. Adding 0.5% mass fraction of polypropylene fiber, the drying shrinkage ratio and moisture loss of the motar also reach minimum values. The drying shrinkage ratio reduces to 0.03% at 28d and moisture loss reduces to 0.39%.
Chaos Behavior and Control of Stay-Cables
Authors: Li Jin Hai , Yan Qing Li , Liu Jin Shuan
Published: February 2012

Stay-cable is infinite dimensional nonlinear dynamical system with a very complex vibration types and mechanism which are not described reasonably yet. In order to better control its dynamic behavior, it is necessary to study complex dynamic behavior carefully. Fistly, partial differential equation of the cable motion is established based on the parabolic initial configuration and is simplified into n Duffing-equations by using Galerkin method. Secondly, the chaos behaviors of the first order Duffing-equation under periodic excitation are studied by taking advantage of Melnikov method. At last , parameters may lead to chaotic motion of a true cable in laboratory are calculated and the methods of chaos control are discussed briefly. The study shows that: 1. First order vibration of cable under periodic excitation has much more complex behaviors than the freedom vibration; 2. The Melnikov method can be very effective and convenient for the analysis of chaotic motion of cable.
The Research of Pile Load Test on Permafrost Regions
Authors: Wang Xu , Wang Li Feng , Wang Zi Qiang , Feng Yong Hang
Published: February 2012

Through conducting load test on reinforced concrete piles of the bridge in Kunlun Pass Basin, the research is mainly about pile foundation bearing capacity on permafrost regions. The paper expounds the fundamental of pile vertical load test and the loading method. Through analyzing the test data, what can be concluded is that it can be close to actual working condition of piles when pile load test is conducted on permafrost regions. Meanwhile, reference data is provided for future bridge projects in the application of pile on permafrost regions.
Full-Scale Segment Model Test and Stress Analysis of Abnormally Shaped Anchorage Zone of Cable-Stayed Bridge Pylon
Authors: Li Yue , Cai Qin Feng
Published: February 2012

The anchorage zone of pylon is the key part of the cable-stayed bridge, and it is also the difficult and important part in designing and construction of cable-stayed bridge. Especially for an abnormally shaped anchorage zone, it is hard to analyze the actual stress distribution on the bridge pylon by a simple mechanical method. The full scale segment model test of the abnormally anchorage zone of Maling River cable-stayed bridge pylon was described. In the test, the cracks, stress and deformation were observed and analyzed. Further more, the finite element analysis for the segment model was carried out. Through the contrast analysis between the model test and the finite element analysis, some important conclusions are drawn such as the model test and the finite element analysis have a good agreement, “the joints outside” and “the polyline inside” are the easy cracking zones, the cracking resistance coefficient of the model is no less than 1.3 and the destroy safety coefficient is no less than 1.6, which can provide important theoretical basis for the design and construction.
Stability Analysis during Concrete Pumping for a CFST Arch Bridge Rib
Authors: Chen Yan Jiang , Ren Xiao Qiang , Wang Jin Jie , Gu Da Peng
Published: February 2012

Abstract. This paper lists the problems during the stability analysis of long span CFST arch bridge and the corresponding modeling method. Based on the construction control of an orthotropic long span CFST arch bridge, a FEM model had been established to analysis the stability of its rib during the concrete pumping. The conclusion shows significant importance to the bridge’s construction process.
Reliability Analysis and Sensitivity Design of the Uniform Strength Component
Authors: Liu Qiao Ling , Xing Hai Feng , Zhang Tian Xiao
Published: February 2012

In this study, the reliability sensitivity of the uniform strength Variable Cross-section Component is analyzed, which is the normal distribution. We propose a method for the reliability and sensitivity of the Uniform Strength Components. We may accurately obtain the uniform strength component's reliable sensitivity information on basic of random variable probability characteristic for certain situation. Through the value examples, we have studied the random variable reliable sensitivity for dangerous sections. We propose a design method with practicality for the uniform strength components.
An Experimental Study on the Fire Behavior of CFT Columns under the Constant Axial Loading Condition in Fire
Authors: Kim Hyung Jun , Kim Heung Youl , Yeo In Hwan
Published: February 2012

The temperature of the steel tube of a CFT column rises rapidly upon a fire causing the deterioration of its strength, while the concrete inside of the tube having large heat capacity provides fire-resistance performance. In order to employ CFT columns as fire-resistant structure, it is necessary to conduct studies on the factors exerting influence on structural capacities and the influence associated with each condition. Concrete’s compressive strength, cross-sectional size, axial load ratio and boundary condition are the major factors which are influential in fire-resistance performance. In particular, boundary condition between columns and beams is one of the major factors which decide fire-resistance performance because it exerts influence on load carrying capacity. The result of the test conducted in this study showed that fire-resistance time of 106 minutes was secured in the specimens with clamped ends and that of 89 minutes in those with pinned ends when cross-sectional size was 360 by 360. In the specimens with cross-sectional size of 280 x 280, fire-resistance time of 113 minutes was secured under the condition of clamped ends and that of 78 minutes was secured under the condition of pinned ends.
Research on the Technology of Defects Detection in Prestressed Pipe Grouting
Authors: He Xiao Yu , Liu Jing , Guo Yi Lin
Published: February 2012

Nondestructive testing technology on prestressed pipe grouting is an important issue in recent years. Some research methods including Radar Method, Ray Method, and Impact Echo Method were contrasted and verified in this paper. The applicable scope and the defect detectable effect of these methods mentioned above was studied exploringly. The achievements obtained this paper were certain to be significant for the detection on pipeling grouting quality and defect inside concrete.
Influence of Reinforcement on Temperature and Stress of Hollow Pier
Authors: Wu Yun Fang , Sun Yan Yan
Published: February 2012

This paper put circular hollow bridge pier under cold wave as an example. Based on solid heat conduction principle, we selected its border and initialized condition according with actual circumstance. Combining solid heat conduction differential equation and generalized hooke’s law which takes temperature stress into account, we have calculated the temperature and stress of concrete piers with different reinforcement ratio by ANSYS finite element software. These results indicate that the longitudinal bars and horizontal ring stirrups in concrete circular hollow pier under cold wave will increase its outer surface temperature tensile stress. Namely the reinforcements in concrete circular hollow pier not only do not prevent its outer surface cracks under the action of cold wave, but will also promote the surface cracks to produce faster. Therein, the contribution of horizontal ring stirrups to the surface cracks is greater than the longitudinal bars.
Fuzzy Comprehensive Evaluation and Empirical Study of BT Mode Transaction Structure Scheme Design for College Campus Constructing
Authors: Yao Chuan Qin , Wang Chao , Ma Hai Bin
Published: February 2012

This paper mainly studied the basic principles and methods of the application of fuzzy mathematics to the transaction structure scheme design evaluation of BT(build transfer) mode for university campus construction, also set up multi-level rating index for university campus construction, and decided the weight coefficient and the information collection system. It illustrated the feasibility of this method by empirical study and offered strong theoretical foundation for project decision.
Damage Localization of Output-Only Frame Systems Using Stochastic Subspace Identification
Authors: Wang Yen Po , Lin Yi Ting , Huang Gang
Published: February 2012

Assurance of integrity of structures is the main task of structural health monitoring. The condition (health) of a structure may be revealed from its dynamic characteristics in response to natural or man-made loads. As the measurement of the natural or operating forces on actual real-life structures is generally formidable, dynamic characteristics of the structures have to be extracted from the available output signals only. The stochastic subspace identification (SSI) technique is adopted in this study to identify the equivalent system parameters of the discrete-time state equation using covariance functions of the measured output signals. With the system parameters realized, the method of damage locating vector (DLV) is then considered for further assessment. Members with nearly zero stress under the loadings of DLVs are considered potentially damaged, whereas the DLVs are derived from singular value decomposition of the change in flexibility matrix of the structure before and after the damage state. In this study, the feasibility of DLV method for damage detection of a planar structure is explored based on its seismic responses. To comply with the desired output-only scenario, the information of ground motion is discarded in the stage of SSI analysis. Despite the non-stationary nature of earthquakes, the proposed scheme has been proved sufficient for damage localization of structures from global responses (floor accelerations). The damaged locations can be identified when the structure is fully observed, regardless of single or multiple damages. In the case of partial but co-located observation (damaged floors observed), the damaged locations can still be identified with acceptable accuracy and reliability.
The Elastic Solution for Internal Force and Deformation of the Muti-Bracing Sustaining Structures
Authors: Kong De Zhi , Wei Jun Jun , Song Yan Xiang
Published: February 2012

This paper analyze the principle of the soil pressure caused by the sustaining structures. The author divides the soil pressure into two parts: first part is generated by digging and unloading and the value is close to the static value; another part is generated by resisting soil force related to the displacement of the structure and the value is proportional to the displacement, and applied the horizontal bedding coefficient of the sectioned stable value. And based on the elastic mechanical theory, the author established the flexing formula of these structures and answered it. And at last, this paper proved the practicality of this solution by a certain foundation test.
The Experimental Study on the Performance of the Reinforced Red Mudstone Using Triaxial Tests
Authors: Zhuo Shuai , Wang Ning , Lu Ping , Yao Yong
Published: February 2012

via the red mudstone proceed of the unconsolidated and non-drained triaxial compression test, the research in different degree of compaction reinforcement material under the influence of red mudstone strength. To the different reinforcement layers, different ambient pressure test, analyses not reinforcement material layer number of decorate the more the better, decorate three layer of steel material is better than the four layers of reinforcement decorate material sample. The analysis in different degree of compaction element soil and reinforced soil under test result, the reinforcement material that can obviously increase the strength of the soil, and in different degree of compaction soil under the different strength, and with the degree of compaction to improve the stress-strain relationship curves by strain softening type to strain change sclerosis type. Analysis of the С value of the red mudstone compaction degree with the increased and rise, but theφ rise and reduced.
Finite Element Modeling and Structural Behavior of Stainless Steel Plates in Compression
Authors: Zhu Hao Chuan , Yao Jian
Published: February 2012

Featuring for non-linear stress-strain relation, the behavior of thin-wall plates differ widely from stainless steel to carbon steel, which plays a basic role in relevant researches. This paper describes the development of FE models for analyzing stainless steel plates in compression which is based on the existing results of Rasmussen’s test, as well as the strength curve achieved by such advanced FE models. The explicit strength equations and design method are proposed for determining the local buckling strength of stainless plate and cold-formed square and rectangular hollow section in compression. It is shown excellent agreement with test results achieved by using Quach’s model as stress-strain relations in FE models. The proposed design method also exhibits reliable results, which could be used in structural design of stainless steel plates in compression.
Characteristics of Fouling in Urban Sewage Source Heat Pump System
Authors: Zhang Cheng Hu , Yang Zhi Gang , Sun De Xing
Published: February 2012

Abstract—The article describes the growth and thermal resistance characteristics of the debris formation of the urban sewage source heat pump system, and describes the common measures.
Stability of Geotechnical Material by Safety Factor of Rock Mass Element
Authors: Xie Xiong Gang , Yu Zhao Yang , Dai Zhang Yin
Published: February 2012

In order to study the safety situation in each part of rock mass, the element safety factor Fe is introduced to estimate the micro-stability of rock mass; the equation for the element safety factor is deduced by the theoretical analysis. Rather than base an engineering design decision on a single calculated factor of safety, an approach which is frequently used to give a more rational assessment of the risks associated with a particular design is to carry out a sensitivity study. This involves a series of calculations in which each significant parameter is varied systematically over its maximum credible range in order to determine its influence upon the factor of safety. In the present paper, the element safety factor Fe is introduced to estimate the micro-stability of rock mass; the equation for the element safety factor is deduced by the theoretical analysis, and the influential factors to the element safety factor is studied.
Geology Analysis and Support Scheme Design in Soft Rock Coal Mine
Authors: Li Cheng Liang , Li Zhao Yan
Published: February 2012

In this paper, Dongrong mine encountered soft rock geological problems as the research object, from the field investigation, laboratory analysis, program design and numerical simulation of four aspects of the problem spread out concrete research. Combining engineering geological conditions and scene construction condition, adopt big deformation nonlinearity theory and design procedures. Study the instability of soft rock tunnel, rock mineral composition and structure. Soft rock tunnel shoring method has carried out the three-dimensional numerical simulation.Studies have shown that pre-stressed anchor supporting technology can effectively control the roof deformation, single-arch bottom floor heave phenomenon can be reduced.
Contrastive Studies of the Testing Method for the Bearing Capacity and Deformation Modulus of Dynamic Consolidation Backfill Foundation
Authors: Gui Yue , Tao Hui , Zhu Pei Ning , Yang Hua Hai , Deng Tong Fa
Published: February 2012

The study collected a great deal of testing data, including the physical properties of soil before dynamic compaction and in-situ test and laboratory test data after dynamic consolidation, from twenty-eight engineering practices about dynamic consolidation granite residual soils(GRS) backfill foundation in power construction in Guangdong province over the past fifteen years. The backfill were classified into three types according to the fraction of soil, the corresponding foundations were classified into three types too. Base on the plate loading testing (PLT), the suitability of testing the bearing capacity and deformation modulus of dynamic Consolidation backfill foundation, by dynamic penetrating testing (DPT), standard penetrating testing (SPT) and laboratory soil testing (LST), were evaluated. The statistic relationships between SPT, DPT blow count and the bearing capacity, deformation modulus of dynamic consolidation backfill foundation were also generalized; as well as the factors influent the testing results were analyzed. And the accuracy of adopting two common region specifications to determine the bearing capacity and deformation modulus were analyzes. This article has some reference value on ground treatment detection of dynamic consolidation backfill foundation with similar engineering geological conditions.
Influence of Matric Suction on Shear Strength Behavior of Unsaturated Silty Sand
Authors: Dong Qian , Liu Liu , Hou Long
Published: February 2012

In order to research matrix suction how to influence the shear strengt of unsaturated silty sand. Based on the analysis of the Soil-water characteristic of unsaturated silty sand through pressure plate instrument test,the suction control direct shear tests under the different suction condition of unsaturated silty sand are studied. And then, the microscopic structure of two kinds soil sample with different water content are scanned to analyze the relationship between the matrix suction and the shear strengt of unsaturated silty sand. The results of the research show that unsaturated silty sand different from unsaturated clayey soil.When water content gradually reduce, the soil shear strength of unsaturated silty sand is not always increased with the increase of matrix suction, but there is a "peak effect".The appearance of "peak effect" is due to unsaturated silty sand has own microstructure characteristics.On the other hand, when the moisture content reduction constantly,the existence form of moisture change gradually.The two factors lead to the effect area of matrix suction change constantly,and then influence shear strengt of unsaturated silty sand to appear "peak effect". In addition,the stress environment also can influence contribution degree of matrix suction to the shear strengt of unsaturated silty sand.
Analysis of Monitoring and Measurement for Heishan Tunnel
Authors: Tian Wen Ling , Li Qi , Xiao Cheng Zhi
Published: February 2012

Abstract: For the purpose of stability of surrounding rocks of tunnel during the stage of construction and operation, a series of monitoring methods and measurement are carried out to investigate performance of Heishan tunnel through selecting 5 cross sections for monitoring. Based on the monitoring data, convergence around tunnel, displacement of different points of interior of surrounding rock, axial forces of rock bolts and pressure of surrounding rock are analyzed. The characteristics of selected cross sections are useful for engineers to optimize the preliminary design of tunnel. Furthermore, the study results can be used to guide the design, monitoring and construction for future tunnels with the similar geological condition.
Lateral Load Distribution of Articulated Hollow Slab Beam Bridge Strengthened by Transverse Prestressed Force
Authors: Xiang Yi Qiang , Xing Cheng , Shao Lin Hai , Xing Yuan
Published: February 2012

Abstract. Aiming at the features of the articulated hollow slab beam bridges with transverse prestressed force, an assumption that regards the reinforced slab beam bridges as analogy orthotropic plate was proposed. The lateral flexural stiffness and torsional stiffness of the plate bridges per meter width can be calculated approximately as an average value of those of the solid section and the minimum hollow section. The longitudinal flexural stiffness and torsional stiffness per meter width remain the same as the original ones. The modified G-M method for calculating the strengthened bridge was proposed. Example as a typical hollow slab bridges, the lateral load distribution influence-line after strengthening bridge obtained by using modified G-M method. The numerical analysis before and after strengthening bridge by using FEM was complete to gain lateral load distribution influence-line. It shows that the values predicted by the proposed modified G-M were matched with the results by the FEM after strengthening bridge. It shows that the method strengthening articulated hollow slab beam bridges by exerting transverse prestress steel wire on them proved to be effective and the presented modified G-M theory to be right.
The Relationship between Retaining Wall Deformation and Earth Pressure in Deep Excavation
Authors: Peng She Qin , Zhao Qi Hua , Chen Zi Yang
Published: February 2012

Earth pressure may change with retaining wall deformation in the process of deep excavating. But how? The answer can be very important to the safety of retaining system. Using monitoring data of north anchor foundation pit of Runyang suspension bridge, this paper studied retaining structure and soil interaction. Find the relationship between retaining wall deformation and earth pressure in deep excavation. In this case, earth pressure increased with wall deformation upward the depth of 18m and decreased with wall deformation down below. A regression equation about foundation pit depth and ratio of earth pressure and wall deformation was established. Then give a simplified earth pressure calculation method considering retaining wall deformation.
Semi-Active Vibration Control Structure with MR-TLCD under Wind Load
Authors: Sun Hong Xin , Wang Xiu Yong
Published: February 2012

The equation of motion for the coupled system of structure—MR-TLCD is formulated by Lagrange equations in this paper. Wind load response of a single-degree-of-freedom structure with MR-TLCD is obtained by time domain method. From the point of view energy dissipation force of MR-TLCD, the Simple Bi-State (SBS) control algorithm control algorithm is developed based on energy dissipation. By applying semi-active and passive control strategies, the controlled wind load response of the coupled system excited by wind load are numerically simulated. The peak value and root mean square value of the displacement and acceleration are obtained and the control effects of the system using the SBS algorithms. The results showed that the wind load responses of the coupled systems could be controlled effectively by applying the MR-TLCD.
Studies on the Index of Energy Momentary Change Rate for Sliding Base-Isolated Structures on Different Level of Friction Coefficient
Authors: Sun Min , Tong Li Ping
Published: February 2012

Being the research object,the index of energy momentary change rate for sliding base-isolated structure is put forward and its corresponding design formulas are given，and three indexes of energy momentary change rate for sliding base-isolated structure including input energy,restorable energy of superstructure and friction energy dissipation on different level friction coefficient are analyzed numerically from the angle of energy.Research shows that energy momentary change rate is a very effective index for energy analysis of sliding base-isolated structure,and there are big relations between the index and isolation layer’s friction coefficient,and the index can reflect well momentary changes of all kinds of energy for every moment.
The Study of Field Effect through Uniaxial Compression Experiment on Marine Recycled Concrete Specimen Based on DPDM Technique
Authors: Liu Wen Bai , Shen Chao , Li Xia , Jiang Hong Ming
Published: February 2012

Recycled concrete is a kind of composite heterogeneous material. Through the uniaxial compression experiment on recycled concrete specimen, the corresponding stress-strain curve is depicted with the major variables of replacement rate of recycled aggregate and time of corrosion by seawater, and the analysis of compression resistance capacity of recycled concrete sample is carried out by comparing common samples with those after the process of vacuum pumping. According to the results of comparison, the process of vacuum pumping can raise the strength of concrete by 9% to 22% and the lowering speed of compression resistance capacity rises as replacement rate of recycled aggregate goes up after the same corrosion period. The compression resistance capacity of the concrete specimen with replacement rate of 60% descends 50% to 80% faster than the sample with 30% of rate. DPDM technique is used to analyze deformation field, displacement field and strain field of concrete specimen during the process of uniaxial compression. As shown in the images from the experiment, the cracks develop from the bottom and both edges towards the middle part along the direction of loading until some of them run through the cube with the failure of the overall specimen while the stress reaches the peak, the displacement amount decreases from bottom to top and from both edges to center and the greatest strain concentration scatters around the bottom of the specimen while the strain of 62% appears around the peak stress of 33-36MPa. This paper puts forward constructive references and guidance for the application of recycled concrete in marine engineering on the basis of the study of field effect through uniaxial compression experiment based on DPDM technique.