scholarly journals Analysis of the Generating and Influencing Factors of Vertical Cracking in Abutments during Construction

2018 ◽  
Vol 2018 ◽  
pp. 1-13 ◽  
Author(s):  
Xingwei Xue ◽  
Junlong Zhou ◽  
Xudong Hua ◽  
Hongnan Li
Keyword(s):  
Mechanical Properties ◽  
Pile Foundation ◽  
Age Difference ◽  
Construction Process ◽  
Factors Affecting ◽  
Crack Control ◽  
Temperature Changes ◽  
Concrete Shrinkage ◽  
Pile Cap ◽  
The Impact

In order to analyze the causes of cracking in abutments subject to concrete shrinkage and temperature variation during the construction process and to determine factors affecting the mechanical properties of the abutment, nonlinear calculations capturing abutment behavior are conducted with Midas/FEA software. Using these calculations, the cracking mechanism is identified, and the influence of the evaluated factors is analyzed. It is concluded that the deformation between the pile cap and abutment backwall as constrained by a pile foundation when subjected to concrete shrinkage and temperature changes is the basic cause of abutment cracks during construction; these cracks form over the piles and develop upward. For a given reinforcement ratio, the distribution of horizontal crack-control steel using small, closely spaced bars is more beneficial. When pile-bearing capacity meets the standard, the width of the generated cracks tends to decrease with the decrease in the diameter of the piles. The existence of a postcast strip in the abutment backwall also contributes to the decrease in the depth of the crack. Finally, the impact of age difference between the pile cap concrete and abutment backwall concrete on cracking is inconsequential.

Construction Process Numerical Simulation and Experimental Research of Parallel-Adjacent Loess Tunnel

2012 ◽  
Vol 446-449 ◽  
pp. 2186-2191
Author(s):  
Jian Guo ◽  
Qi Cai Wang ◽  
Rong Ling Zhang ◽  
Zhi Guo Yang
Keyword(s):  
Mechanical Properties ◽  
Numerical Simulation ◽  
Experimental Research ◽  
Tunnel Lining ◽  
Tunnel Construction ◽  
Construction Process ◽  
Tunnel Excavation ◽  
Lining Structure ◽  
Loess Region ◽  
The Impact

According to the mechanical properties of the parallel-adjective tunnel, the construction process is simulated and the displacements and concrete stress of the lining structure is monitored of an actual tunnel in the loess region. The influence which the new tunnel on the existing tunnel lining during the new tunnel construction process studied by comparatively analyzed the numerical simulation and monitoring the results. The results show that the impact on the existing tunnel during the new tunnel excavation changes with tunnel distance and the excavation method of the new tunnel, when the line distance increases the impact on the existing tunnel has been remarkably reduced.

The Engineering Accident Analysis of Cast-In Situ Bored Pile

2012 ◽  
Vol 446-449 ◽  
pp. 1514-1519
Author(s):  
Bin Tang ◽  
Ting Wang ◽  
Zi Ning Shan
Keyword(s):  
Pile Foundation ◽  
Bridge Engineering ◽  
Foundation Engineering ◽  
Construction Process ◽  
Floating Pile ◽  
Bored Pile ◽  
Wrong Identification ◽  
Catheter Tube ◽  
The Impact

Abstract: Cast-in situ bored pile is a common form of pile foundation and widely used in road and bridge engineering in China. Because of complex cast-in situ bored pile construction process, high technical content requirement, vulnerable to the impact of human and environmental factors, cast-in situ bored piles prone to various kinds of quality problems in the construction process, such as drilling deflection, drilling hole collapse and diameter reduction, wrong identification of pile-end’s bearing stratum, catheter tube blockage, reinforcement cage floating, pile breaking, pile silted, etc. These problems often make it difficult to meet the design requirements into a pile formation, and difficultly to remedy. In this paper, Zhoutian Zhenjiang bridge at Shaoguan City, Qujiang to Nanxiong highway A03 contract bid package cast-in situ bored pile foundation engineering encountered in the construction collapsed hole, inclined hole, catheter tube blockage and other issues for example to analyzes the cause of cast-in situ bored pile engineering accident, made appropriate preventive measures and processing method.

Computation of Dynamic Characteristics of Deepwater Group Pile Foundation for Bridges

2011 ◽  
Vol 261-263 ◽  
pp. 1510-1514
Author(s):  
Can Xu ◽  
Wan Cheng Yuan ◽  
Kai Wei ◽  
Pak Chiu Cheung
Keyword(s):  
Dynamic Characteristics ◽  
Pile Foundation ◽  
Pile Group ◽  
Vertical Vibration ◽  
Lateral Bending ◽  
Approximate Analytical Solutions ◽  
Simplified Method ◽  
Pile Cap ◽  
Bending Modes ◽  
The Impact

In the design of deepwater foundation for bridges, the interaction between water and the structure especially under earthquake motions should be addressed. This paper presents a practical simplified method to analyze deepwater pile group foundation to determine its dynamic characteristics by combining approximate analytical solutions with the finite element method. The applicability of this proposed method is shown in a case study of a nine-pile foundation. Compared with those from complete numerical method, the analysis results from this simplified method are in agreement when the pile cap is not submerged in water. Furthermore when ignoring the vertical hydrodynamic added mass of the pile cap, the vertical vibration mode results are greatly affected, but not for other non-vertical vibration modes. This simplified method is also used in the study of the influence of water on the dynamic characteristics. The deeper the water is, the more obvious the impact of water is, particularly for the pile cap lateral bending modes, and there appears no evident difference for the pile lateral bending modes, on which water effect is stronger than that on pile cap lateral bending mode.

Shrinkage and Creep of Concrete on the Mechanical Properties of Cable-Stayed Bridge

2012 ◽  
Vol 594-597 ◽  
pp. 1498-1503
Author(s):  
Heng Shan Gao ◽  
Tie Ying Li
Keyword(s):  
Mechanical Properties ◽  
Finite Element ◽  
Element Model ◽  
Main Beam ◽  
Construction Process ◽  
Analysis Software ◽  
Element Analysis ◽  
Concrete Shrinkage ◽  
Cable Stayed Bridge ◽  
Shrinkage And Creep

In this paper, using the universal finite element analysis software SAP2000 to build a large span cable-stayed bridge with finite element model, using a stepwise analysis finite element method to study the concrete shrinkage and creep efforts on the main beam inner force and deformation, cable tension during the cable-stayed bridge construction process and after the bridge. Research results show that the effects of shrinkage and creep in the finished bridge cannot be ignored, and the results can be used as reference for the design of similar projects.

Impact Analysis of Different Cable Types on Saddle-Shaped Cable-Net in Construction Process

2012 ◽  
Vol 479-481 ◽  
pp. 190-193
Author(s):  
Zhan Sheng Liu ◽  
Ran Zhang
Keyword(s):  
Mechanical Properties ◽  
Impact Analysis ◽  
Steel Wire ◽  
Steel Structure ◽  
Element Model ◽  
Wire Rope ◽  
Construction Process ◽  
New Type ◽  
Prestressed Steel Structure ◽  
The Impact

Cable is widely used in the actual project of prestressed steel structure for its mechanical properties can be fully used. Saddle-shaped cable net is a new type of large-span prestressed structure, but there is little study on the impact of different cable types on the mechanical properties of saddle-shaped cable net during the construction. In order to meet the thought of integration of design and construction, a finite element model of saddle-shaped cable net has been established. The four types of cables such as semi-parallel steel tendon cable, steel wire rope cable, steel strand cable and full-locked coil rope are chosen. The impact on mechanical properties of the structure was analyzed by different cable types.

scholarly journals Experimental Study of Dynamic Mechanics Characteristics of Saturated Marble under Low Temperature

2021 ◽  
Vol 2021 ◽  
pp. 1-15
Author(s):  
Yang Yang ◽  
Jianguo Wang
Keyword(s):  
Mechanical Properties ◽  
Low Temperature ◽  
Dynamic Strength ◽  
Fracture Morphology ◽  
Dynamic Mechanical Properties ◽  
Load Test ◽  
Peak Strain ◽  
Temperature Changes ◽  
Dynamic Mechanical ◽  
The Impact

The effect of low temperature on dynamic mechanical properties of low-temperature frozen marble at a high strain rate was studied by a dynamic impact test. The influence of temperature changes (25°C–40°C), especially negative temperature changes, on dynamic strength, peak strain, and failure mode of the marble was analyzed. Combined with the fracture morphology, the reasons for the deterioration of dynamic mechanical strength of water-saturated marble at lower negative temperatures were investigated. The experimental results show that the dynamic mechanical properties of marble are significantly affected by the change of freezing temperature. The dynamic strength firstly decreases and then increases with the decrease of temperature in the range of 25°C to −20°C, but the dynamic strength decreases sharply after −20°C. The peak strain increases first, then decreases, and then increases, and the inflection point temperature of the change is −5°C and −20°C, respectively, which is completely different from the static load test results of frozen rock at low temperature. According to fracture morphology analysis, water-ice phase transformation at −5°C leads to the nucleation and expansion of a large number of microcracks and micropores in marble, and the interaction between slip separation cracks and microstructures caused by shear deformation under impact separates the massive crystals inside the rock into microscopic crystals, thus reducing the bearing capacity and strength of marble. From −5°C to −20°C, the ice medium and marble matrix contract when cooled, and the microcracks and micropores caused by the phase transition gradually close during the contraction process, the integrity of the rock is restored, and the dynamic strength of the rock is increased. At −20°C, there is a great difference in the shrinkage rate of the marble matrix and the ice medium, and the internal microstructure increases. Meanwhile, the impact amplifies the brittleness of the rock at low temperatures, leading to a sharp decrease in the dynamic strength of the marble.

DAMPAK KEBIJAKAN FISKAL TERHADAP KINERJA SEKTOR PERTANIAN DI SULAWESI TENGGARA

2017 ◽  
Vol 1 (1) ◽  
Author(s):  
La Ode Jabuddin ◽  
Ayub M Padangaran ◽  
Azhar Bafadal Bafadal
Keyword(s):  
Fiscal Policy ◽  
Interest Rates ◽  
Agricultural Sector ◽  
Simultaneous Equations ◽  
Poor People ◽  
Land Area ◽  
Factors Affecting ◽  
Historical Simulation ◽  
The Impact ◽  
Direct Expenditure

This study aims to: (1) Knowing the dynamics of fiscal policy and the performance of the agricultural sector, (2) Analyze the factors that influence fiscal policy and the performance                   of the agricultural sector, and (3) Analyzing the impact of fiscal policy on the performance of the agricultural sector. The data used in this study were pooled 2005-2013 data in the aggregate. Econometric model the impact of fiscal policy on the performance of the agricultural sector is built in the form of simultaneous equations, consisting of 7 equations with 25 total variables in the model, 7 endogenous variables, 12 exogenous variables, and 6 variables lag. The model is estimated by 2SLS method SYSLIN procedures and historical simulation with SIMNLIN procedure.The results showed that: (1) The development of fiscal policy in Southeast Sulawesi from year to year tends to increase, (2) The performance of the agricultural sector from the aspect of GDP has decreased, from the aspect of labor is still consistent, in terms of investment to grow positively, and assign roles which means to decrease the number of poor people, (3) factors affecting fiscal policy is local revenues, equalization funds, other revenues, as well as the lag fiscal policy, (4) the factors that affect the performance of the agricultural sector from the aspect GDP is labor, direct expenditure and GDP lag; from the aspect of labor is the total labor force, investment, land area, direct expenditure, as well as the lag of labor; from the aspect of investment is influenced by GDP per capita, land area, interest rates and investment lag; as well as from the aspect of poor people, are affected by population, investments, direct expenditure and poverty lag, (5). Fiscal policy impact on the agricultural sector GDP increase, a decrease in the number of poor, declining agricultural laborers, and a decrease in the amount of investment in the agricultural sector.Keywords: Fiscal policy, the performance of the agricultural sector, the simultaneous equations

Effect of combined drink cans and steel fibers on the impact resistance and mechanical properties of concrete

2020 ◽  
Vol 14 (2) ◽  
pp. 6734-6742
Author(s):  
A. Syamsir ◽  
S. M. Mubin ◽  
N. M. Nor ◽  
V. Anggraini ◽  
S. Nagappan ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Compressive Strength ◽  
Reinforced Concrete ◽  
Impact Resistance ◽  
Fiber Reinforced Concrete ◽  
Steel Fibers ◽  
Fiber Reinforced ◽  
Indirect Tensile ◽  
The Impact

This study investigated the combine effect of 0.2 % drink cans and steel fibers with volume fractions of 0%, 0.5%, 1%, 1.5%, 2%, 2.5% and 3% to the mechanical properties and impact resistance of concrete. Hooked-end steel fiber with 30 mm and 0.75 mm length and diameter, respectively was selected for this study.  The drinks cans fiber were twisted manually in order to increase friction between fiber and concrete. The results of the experiment showed that the combination of steel fibers and drink cans fibers improved the strength performance of concrete, especially the compressive strength, flexural strength and indirect tensile strength. The results of the experiment showed that the combination of steel fibers and drink cans fibers improved the compressive strength, flexural strength and indirect tensile strength by 2.3, 7, and 2 times as compare to batch 1, respectively. Moreover, the impact resistance of fiber reinforced concrete has increase by 7 times as compared to non-fiber concretes. Moreover, the impact resistance of fiber reinforced concrete consistently gave better results as compared to non-fiber concretes. The fiber reinforced concrete turned more ductile as the dosage of fibers was increased and ductility started to decrease slightly after optimum fiber dosage was reached. It was found that concrete with combination of 2% steel and 0.2% drink cans fibers showed the highest compressive, split tensile, flexural as well as impact strength.    

Methodology of studying the mechanical properties of composite materials (reinforced concrete)

2018 ◽  
Vol 84 (12) ◽  
pp. 61-67
Author(s):  
V. A. Eryshev
Keyword(s):  
Mechanical Properties ◽  
Reinforced Concrete ◽  
Experimental Studies ◽  
Analytical Relationship ◽  
Hardened Concrete ◽  
Deformation Model ◽  
Joint Work ◽  
Concrete Shrinkage ◽  
Axial Tension ◽  
Tension And Compression

The mechanical properties of a complex composite material formed by steel and hardened concrete, are studied. A technique of operative quality control of new credible concrete and reinforcement, both in laboratory and field conditions is developed for determination of the strength and strain characteristics of materials, as well as cohesion forces determining their joint operation under load. The design of the mobile unit is presented. The unit provides a possibility of changing the direction of loading and testing the reinforced element of the given shape both for tension and compression. Moreover, the nomenclature of testing equipment and the number of molds for manufacturing concrete samples substantially decrease. Using the values of forcing resulting in concrete cracking when the joint work of concrete and reinforcement is disrupted the values of the inherent stresses and strains attributed to the concrete shrinkage are determined. An analytical relationship between the forces and deformations of the reinforced concrete sample with central reinforcement is derived for axial tension and compression, with allowance for strains and stresses in the reinforcement and concrete resulted from concrete shrinkage. The results of experimental studies are presented, including tension diagrams and diagrams of developing axial deformations with an increase in the load under the central loading of the reinforced elements. A methodology of accounting for stresses and deformations resulted from concrete shrinkage is developed. The applicability of the derived analytical relationships between stresses and deformations on the material diagrams to calculations of the reinforced concrete structures in the framework of the deformation model is estimated.

Sign in / Sign up

Export Citation Format

Share Document