Concrete Shrinkage and Creep Effect Prediction Model and the Influence Factors Analysis

2013 ◽  
Vol 756-759 ◽  
pp. 2051-2054 ◽  
Author(s):  
Rui Fang Duan ◽  
Xiu Fen Huang ◽  
He Zhang
Keyword(s):  
Relative Humidity ◽  
Influence Factors ◽  
Shrinkage Strain ◽  
Complex Problem ◽  
Concrete Creep ◽  
Concrete Shrinkage ◽  
Creep Coefficient ◽  
Creep Effect ◽  
Shrinkage And Creep ◽  
Average Relative Humidity

It is a complex problem that forecast and control the shrinkage and creep of concrete and influence on the performance of the structures.Through the conmparion of all kinds of common model,the article have also analysed the main influence factors about the concrete shrinkage and creep effect . The results showed that JTJ 85 model for shrinkage and creep effect tends to conservative calculation; the creep coefficient and shrinkage strain of JTG D62 model and the CEB-FIP model were basically consistent; and ACI 209 model underestimated the concrete shrinkage and creep effect. Theoretical depth of components was more sensitive to concrete shrinkage strain, and creep coefficient was smaller sensitivity; The effect of concrete creep increases with the decreasing of age at loading, when age of loading percentage increased from three to 28 days, the concrete creep effect of the terminal value reduced about 80%; The influence of environment average relative humidity on shrinkage and creep effect is more sensitive, when environment average relative humidity increased from 50% to 80%, creep coefficient nearly reduced about 30%,and shrinkage strain decreased 50%, in comparison, the influence of environment relative humidity chance on the concrete shrinkage effect is greater than that on creep effect.

A Simplified Concrete Creep and Shrinkage CEB-FIP90 Model in Long-Span Bridge Design

2014 ◽  
Vol 638-640 ◽  
pp. 1059-1062
Author(s):  
Qing Xiang Zeng ◽  
Da Jian Han
Keyword(s):  
Influence Factor ◽  
Shrinkage Strain ◽  
Bridge Design ◽  
Concrete Shrinkage ◽  
Creep Coefficient ◽  
Long Span ◽  
Long Span Bridge ◽  
Shrinkage And Creep ◽  
The Pearl River ◽  
Creep And Shrinkage

The concrete shrinkage strain and creep coefficient calculation method in CEB - FIP MC90 model is briefly introduced. For application convenience in bridge design, a simplified formula for calculation of the concrete shrinkage strain and creep coefficient is derived. Considering the varying range of every influence factor, a correlation analysis for the factor is carried out. And the weights of those factors related to concrete shrinkage and creep coefficient are discussed. Considering the climate characteristics and the bridge structure features in the Pearl River Delta area, the variation ranges of concrete nominal shrinkage strain and nominal creep coefficient are calculated respectively.

scholarly journals Modeling Shrinkage and Creep for Concrete with Graphene Oxide Nanosheets

Materials ◽  
2019 ◽  
Vol 12 (19) ◽  
pp. 3153 ◽  
Author(s):  
Chen ◽  
Xu ◽  
Hua ◽  
Zhou ◽  
Wang ◽  
...  
Keyword(s):  
Graphene Oxide ◽  
Concrete Strength ◽  
Shrinkage Strain ◽  
Influential Factors ◽  
Graphene Oxide Nanosheets ◽  
Model Accuracy ◽  
Modified Model ◽  
Creep Coefficient ◽  
Shrinkage And Creep ◽  
Application Scope

In this study, the shrinkage and creep of concrete containing graphene oxide (GO) nanosheets were experimentally and theoretically investigated. Experiments for the shrinkage and creep of concrete with 0.02% and 0.08% GO nanosheets by the weight of cement and common concrete were carried out. Subsequently, the influence of GO nanosheets on the shrinkage and creep of concrete was analyzed and discussed. A modified model was developed to accurately predict the shrinkage and creep of concrete containing GO nanosheets after models for predicting shrinkage and creep of common concrete were compared and the influential factors and application scope were determined. Results indicate that: (1) GO nanosheets can increase the shrinkage strain and reduce the creep coefficient of concrete, and (2) a modified ACI209 (92) model can accurately predict the shrinkage and creep of concrete containing GO nanosheets. Factors considering concrete strength can be introduced in the model to improve the model accuracy.

SHRINKAGE AND CREEP EFFECT ANALYSES OF DOUBLE COMPOSITE CONTINUOUS BOX-GIRDER BRIDGE CONSTRUCTED BY PRE-JACKING METHOD

2017 ◽  
Vol 4 (1) ◽  
Author(s):  
Shujin Duan ◽  
Bin Wang ◽  
Yuanyuan Wang ◽  
Runming Niu
Keyword(s):  
Composite Beam ◽  
Concrete Slab ◽  
Bridge Construction ◽  
Creep Equation ◽  
Box Girder ◽  
Concrete Creep ◽  
Creep Effect ◽  
Shrinkage And Creep ◽  
Negative Moment ◽  
Girder Bridge

Continuous double steel and concrete composite beam is a new structural system developed on the basis of common steel and concrete composite beam. Controlling concrete slab crack width in a continuous double composite beam is a significant content in the bridge construction process. Jacking-up and landing bearing supports method is applied to a double composite girder bridge construction and its structural mechanical behaviors in the whole process will be simulated. By using of User Programmable Features and ANSYS Parametric Design Language, the commercial FEM software ANSYS was further developed. The exponential model of concrete creep and the implicit solution of concrete creep equation under the action of variable stress were introduced into ANSYS, to realize the concrete shrinkage and creep effect analysis of double composite continuous box-girder bridges constructed by pre-jacking method. The results show that it is improved that the stress state of the top concrete slab in the negative moment regions by pre-jacking method. Due to the effect of concrete creep, the concrete creep will cause tensile stress in the negative moment regions of the composite beam, which will reduce the compressive stress in the top concrete slab. The effect of prestressing is greatly affected by pre-jacking value, and the creep of the concrete also causes the stress redistribution of the concrete and the steel beam.

Prediction Models of Shrinkage and Creep for Concrete Columns

2011 ◽  
Vol 243-249 ◽  
pp. 1583-1588
Author(s):  
Yi Gang Lv ◽  
Jian Ren Zhang ◽  
Kang Xu
Keyword(s):  
Prediction Models ◽  
Plain Concrete ◽  
Least Square Method ◽  
Concrete Columns ◽  
Shrinkage Strain ◽  
Least Square ◽  
Creep Effect ◽  
Shrinkage And Creep ◽  
Term Performance

In constant temperature and humidity environment, the properties of shrinkage and creep for a group of plain concrete and reinforced concrete columns were observed in long-term and experimental method. The curves of concrete shrinkage and creep effect with time were obtained. Checking coefficient and type coefficient of shrinkage and creep effect were put forward in order to predict models of shrinkage and creep. Using the least square method, functions of checking coefficient and type coefficient were acquired and the prediction models of shrinkage strain and creep coefficient of concrete were obtained based on the modification of the formula of JTG D62-2004. The foundation is laid for the application of the long-term performance research in bridge structure.

Models for Autogenous Shrinkage in Low Water-Binder Ratios Concrete

2012 ◽  
Vol 487 ◽  
pp. 435-439
Author(s):  
Qiao Zhu ◽  
Lin Hua Jiang ◽  
Jin Xia Xu
Keyword(s):  
Physical Mechanism ◽  
Prediction Models ◽  
Autogenous Shrinkage ◽  
Complex Problem ◽  
Research Trends ◽  
Future Research ◽  
Concrete Shrinkage ◽  
Shrinkage And Creep ◽  
Binder Ratio ◽  
Capillary Tension

Non-structural cracking of concrete is a serious problem and the underlying phenomena, namely, shrinkage and creep, need to be better understood. Much research has been devoted to this complex problem. However, despite major successes, the phenomenon of autogenous shrinkage is still far from being fully understood. The paper discusses the main aspects of concrete shrinkage, with a focus on autogenous shrinkage, which are especially important in low water/binder ratio concrete. These aspects include the theories of physical mechanism, prediction models and future research trends. Shrinkage of concrete due to moisture changes, which result in surface and capillary tension, was reviewed. The mechanisms often cannot be directly linked to the macroscopically observed dilatation/contraction. An overview of recent model developments is also presented.

Corrosion Behaviors of Mg-7Gd-5Y-1Nd-0.5Zr Alloys in CO2 Atmosphere under Different Relative Humidity

2014 ◽  
Vol 900 ◽  
pp. 39-42
Author(s):  
Quan Tong Jiang ◽  
Xing Gang Li ◽  
Yong Jun Li ◽  
Ming Long Ma ◽  
Guo Liang Shi ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Weight Loss ◽  
Relative Humidity ◽  
Influence Factors ◽  
Corrosion Morphology ◽  
Corrosion Rates ◽  
Corrosion Behaviors ◽  
Peak Aged ◽  
Residual Mechanical Properties ◽  
Loss Rates

The corrosion behaviors of peak-aged Mg-7Gd-5Y-1Nd-0.5Zr alloys in CO2atmosphere under different relative humidity were investigated by OM, SEM. The weight loss rates, corrosion morphology and residual mechanical properties were also analyzed. The corrosion rates of specimens in CO2atmosphere at 70% relative humidity were highest than others. Relevancy of the influence factors included relative humidity and concentration of CO2were researched. The results show that relative humidity and concentration of CO2in the environment both played an important role in corrosion behaviors.

scholarly journals Investigation of monthly variations in the efficiencies of photovoltaics due to sunrise and sunset times

2020 ◽  
Vol 18 (1) ◽  
pp. 310
Author(s):  
Armstrong O. Njok ◽  
Julie C. Ogbulezie ◽  
Manoj Kumar Panjwani ◽  
Raja Masood Larik
Keyword(s):  
Relative Humidity ◽  
Solar Energy ◽  
Electrical Energy ◽  
Time Of Day ◽  
Peak Efficiency ◽  
Pv Module ◽  
Average Relative Humidity ◽  
The Difference ◽  
Monthly Variations ◽  
Different Levels

<p>The effect of time of day and month on the efficient conversion of solar energy to electrical energy using a polycrystalline (PV) module in calabar was studied. A KT-908 precision digital hygrometer and thermometer, and a M890C+ digital multimeter were used in the process. Results obtained shows that photovoltaic produce different levels of peak efficiencies at different times of the day for different months due to the difference in sunrise and sunset times for the months. The results also indicated that photovoltaics will be more efficient in months with low average relative humidity couple with low panel temperature. A peak efficiency of 77% at 12:30 in the month of April was observed before dropping to 73% at 12:00 in the month of May, indicating that there might be further drop in efficiency as we proceed further into the year. Results also show that photovoltaics are more efficient before noon in the month of May than in April while the reverse will be observed in the afternoon. </p>

scholarly journals Karakteristik Pengeringan Biji Jagung (Zea Mays L.) Menggunakan Alat Pengering Surya Adriyarkara Termodifikasi

2018 ◽  
Vol 3 (2) ◽  
pp. 351-360
Author(s):  
Athul Fadhli ◽  
Diswandi Nurba ◽  
Raida Agustina
Keyword(s):  
Zea Mays ◽  
Relative Humidity ◽  
Moisture Content ◽  
Zea Mays L ◽  
Initial Moisture Content ◽  
Solar Irradiation ◽  
Air Velocity ◽  
Drying Time ◽  
Average Temperature ◽  
Average Relative Humidity

Abstrak. Jagung merupakan tanaman penghasil karbohidrat terpenting. Pengeringan jagung pipil menggunakan alat pengering merupakan proses untuk menghasilkan jagung pipil yang siap diolah untuk pembuatan tepung jagung dengan batas kadar air tertentu sehingga menghaslkan jagung pipil dengan kualitas yang baik. Tujuan penelitian ini adalah untuk mengkaji karakteristik pengeringan biji jagung menggunakan alat pengering surya Termodifikasi. Metode penelitian  menggunakan 3,15 kilogram jagung pipil dengan kadar air awal 22% untuk proses pengeringan. Parameter yang dianalisis terkait alat pengering kolektor surya yaitu temperatur, kelembaban relatif, kecepatan udara dan iradiasi surya, sedangkan parameter yang dianalisis terkait bahan yaitu kadar air, lama waktu pengeringan, laju pengeringan dan organoleptik. Prosedur penelitian terdiri dari pengujian kosong dan pengujian dengan menggunakan jagung pipil. Hasil penelitian menunjukkan bahwa temperatur rata-rata dalam rak pengering sebelum dilakukan modifikasi yaitu 44,4oC, temperatur rata-rata setelah dilakukan modifikasi yaitu 55,5oC dan temperatur rata-rata rak pengering pada pengeringan menggunakan jagung pipil yaitu 46,96oC. Kelembaban relatif rata-rata dalam rak pengering sebelum dilakukan modifikasi yaitu 40,1%, kelembaban relatif rata-rata dalam rak pengering setelah modifikasi yaitu 35,1% dan kelembaban relatif rata-rata pengeringan menggunakan jagung pipil yaitu 44,45%. Dari hasil pengukuran tersebut menunjukkan bahwa nilai temperatur dan kelembaban pada alat setelah modifikasi lebih baik dibandingkan sebelum alat dimodifikasi. Pengukuran temperatur dan kelembaban relatif terdiri dari 4 titik pengukuran yaitu rak 1A,1B dan rak 2A, 2B. Kecepatan udara rata-rata yang diukur konstan yaitu 0,7 m/s pada ruang pengering, sedangkan lingkungan 1,1 m/s. Total iradiasi surya selama pengeringan yaitu 1848,84 W/m2. Kadar air jagung pipil masing-masing rak yaitu rak 1A 14,29%, rak 1B 14,47%, rak 2A 13,91% dan rak 2B 14,1%. Hasil dari pengujian organoleptik, panelis agak menyukai jagung pipil yang dikeringkan menggunakan alat pengering tersebut.Characteristics of Seed Drying (Zea mays L.) Using a Modified Adriyarkara Solar DryerAbstract. Corn is the most important carbohydrate plant. Drying corn using a drying tool is a process to produce corn that are ready to be processed for making corn flour with a certain water content limit so as to produce corn with good quality. The purpose of this study was to examine the characteristics of drying of corn kernels using a modified solar dryer. The research method used 3,15 kilogram of corn milled with the initial moisture content of 22% for drying process. The parameters analyzed in relation to solar collector dryers are temperature, relative humidity, air velocity and solar irradiation, while the parameters analyzed are materials such as moisture content, drying time, drying rate and organoleptic. The research procedure consists of unloaded testing and testing using corn. The results showed that the average temperature in the dryer tray before modification was 44,4°C, the average temperature after modification was 55,5°C and the average temperature of the dryer tray on drying using corn was 46,96oC. The average relative humidity in the dryer tray before modification is 40,1%, the average relative humidity in the dryer tray after modification is 35,1% and the average relative humidity of drying using corn is 44,45%. From the measurement results show that the value of temperature and humidity in the tool after modification is better than before. Measurement of temperature and relative humidity consist of 4 point of measurement that is tray 1A, 1B and tray 2A, 2B. Average mean air velocity measured is 0,7 m/s at the dryer room, while the environment is 1,1 m/s. Total solar irradiation during drying is 1848,84 W/m2. Moisture level of corn each shelves tray 1A is 14,29%, tray 1B is 14.47%, tray 2A is 13,91% and tray 2B is 14,1%. As a result of organoleptic testing, panelists rather like dried corn using the dryer.

scholarly journals The Effect of Temperature and Humidity May Reduce the Growth Rate of the Coronavirus Disease 2019 Epidemic

2020 ◽  
Author(s):  
Lei Qin ◽  
Qiang Sun ◽  
Jiani Shao ◽  
Yang Chen ◽  
Xiaomei Zhang ◽  
...  
Keyword(s):  
Growth Rate ◽  
Relative Humidity ◽  
Effect Of Temperature ◽  
Average Temperature ◽  
Temperature And Humidity ◽  
Scatter Plots ◽  
Low Humidity ◽  
Average Relative Humidity ◽  
Effects Of Temperature ◽  
The Relationship

Abstract Background: The effects of temperature and humidity on the epidemic growth of coronavirus disease 2019 (COVID-19)remains unclear.Methods: Daily scatter plots between the epidemic growth rate (GR) and average temperature (AT) or average relative humidity (ARH) were presented with curve fitting through the “loess” method. The heterogeneity across days and provinces were calculated to assess the necessity of using a longitudinal model. Fixed effect models with polynomial terms were developed to quantify the relationship between variations in the GR and AT or ARH.Results: An increased AT dramatically reduced the GR when the AT was lower than −5°C, the GR was moderately reduced when the AT ranged from −5°C to 15°C, and the GR increased when the AT exceeded 15°C. An increasedARH increased theGR when the ARH was lower than 72% and reduced theGR when the ARH exceeded 72%.Conclusions: High temperatures and low humidity may reduce the GR of the COVID-19 epidemic. The temperature and humidity curves were not linearly associated with the COVID-19 GR.

Study on Prediction Model of Shrinkage and Creep of Prestressed Concrete Beam in Passenger Dedicated Line

2011 ◽  
Vol 255-260 ◽  
pp. 3998-4002
Author(s):  
Jun Li Luo ◽  
Zhi Sheng Xu ◽  
Jun Li ◽  
Ji Hao Yang
Keyword(s):  
Prestressed Concrete ◽  
High Speed ◽  
Concrete Beam ◽  
Influence Factors ◽  
Creep Model ◽  
High Speed Railway ◽  
Modified Model ◽  
Shrinkage And Creep ◽  
Prestressed Concrete Bridge ◽  
Passenger Dedicated Line

To improve the calculation precision of deformation in prestressed concrete bridge in passenger dedicated line and accurately predict the development of shrinkage and creep in bridge, a universal applicable modified model was put forward in this paper based on ACI 209R(1992) shrinkage and creep model. In the modified model, three influence factors-slump, strength and reinforcement - are corrected. And the modified model results were compared with the experimental results. It shows that the modified model can more accurately predict the development of shrinkage and creep of high-speed railway bridge and better accord with the law of it.

Sign in / Sign up

Export Citation Format

Share Document