Concrete Pouring Process Research Articles

Analysis of roof stability in ultra-large LNG storage tanks based on field measurements

ABSTRACT To ensure an accurate assessment of the stability of the steel roof during construction of ultra-large LNG storage tanks, real-time monitoring throughout the entire concrete roof pouring process of the world's largest 270,000 cubic meter LNG storage tank was implemented. A computational model for the stability of the steel roof during construction course was established, and the influence of time interval between pours, the holding pressure, and the volume of concrete poured on the stability of the steel roof were studied. The results show that the stability of the steel roof can be enhanced significantly by increasing the time interval between pours within the first eight days after each pouring. Increasing the holding pressure can improve the stability of the steel roof, with more significant effects observed when the time interval between pours is shorter. The volume of concrete poured plays a critical role in structural stability.

Research on Temperature Control of Mass Concrete for Multi-Tower Cable-Stayed Bridge Cap during Construction

In the construction process of mass concrete structures, the large temperature gradient due to exothermic hydration makes the mass concrete highly susceptible to cracking. This paper carried out research on temperature control methods of mass concrete for the purpose of ensuring construction quality based on the construction of Fengyi cable-stayed bridge caps. Firstly, the temperature and stress change rule in the concrete pouring process of the caps was analyzed though the finite element method (FEM). Then, targeted-oriented comprehensive temperature control schemes were formulated according to the structural characteristics and construction environment of the cap, including the optimization of the material ratio, the arrangement of crack-resistant reinforcing steel, the design of a water pipe cooling scheme and reasonable maintenance. Finally, the whole bridge cap construction process using the optimized water pipe cooling solution was monitored, and the temperature gap between inside and outside the concrete satisfied the specification requirements rigorously. In the concrete demolding session, the concrete surface was smooth and no cracks were found, which indicates the temperature control scheme is reasonable and effective. The research results have reference significance for the pouring and temperature control of mass concrete for bridge caps.

Evaluation on structural characteristics of the spiral case influenced by external concrete

Abstract As hydropower is developing vigorously, hydraulic-turbine units have to experience higher head to balance the large power production and consumption on the grid. It requests for higher level of structural strength and stability during operation. Water-filled and pressure-retaining spiral case is commonly used in the power houses of large-scale hydropower stations, which has a good joint bearing capacity of internal water pressure. In this paper, finite element models of the water-filled and pressure-retaining spiral case with and without external concrete under preloading pressure are established, which are used to simulate the structural characteristics when the water-filling process and concrete pouring process are completed. The results show that the maximum stress and deformation of the spiral case are significantly reduced by almost 50% under the support of concrete. Both of them are located at the inner edge and are about 200.80 MPa and 0.60 mm, respectively. The reason why the maximum stress and deformation positions of the spiral case changes after the external concrete being poured is the structural characteristics of concrete, which determine its stress and deformation distribution, and then affect the restraint effect of the corresponding area on the spiral case. The concrete can share parts of the preloading pressure from the spiral case that greatly improves the joint bearing capacity and stability of the overall structure. The conclusions in this paper can also be applied to evaluate the influence of external concrete on the spiral case structural characteristics for similar spiral case structure.

Intelligent Analysis of Hydraulic Concrete Vibration Time Based on Convolutional Neural Network

The vibrating of concrete is one of the most important procedures that directly determines the quality of construction projects. The concrete vibration quality in field construction is mainly judged by the experience of workers, lacking quantitative indicators, and necessary supervision. However, the lack of research about concrete vibration quality led to these problems are still existing. There are some methods are proposed that are too difficult, or too expensive to use in field construction. Combined with the pouring project of Jianquan Pumped Storage Power Station in Yunyang, China, this research developed an intelligent detection system for concrete vibration time. The system took the convolutional neural network as the basic framework, and divided the concrete vibration process into three different states: vibrating, not vibrating, and no vibration tube, realized the concrete vibration time through the analysis of concrete vibration video data. The detection of concrete vibration process video with multiple stages in the actual project shows that the detection error of the system for each state is kept within 1 s, the accuracy is high, which can meet the quality management requirements of the construction process. The system can be quickly deployed to the construction site by using mobile phones, cameras, and other common equipment. It has the advantages of simple frame structure, low hardware requirements, and accurate detection results. In addition, the current system training process is only for the concrete pouring process of Jianquan Power Station, and the training sample can be further expanded in the future to enhance the applicability and accuracy of the system in other engineering applications in order to play a better role.

Analysis of the safety impact of mobile rail hydraulic spreader on residential building machines under the system of building machines

The construction industry in China is a labor-intensive industry, but the cheap labor force has begun to change in recent years, with labor costs rising. In some labor exporting provinces, there has even been a "battle for talent.". Based on this, the "14th Five Year Plan" construction industry development plan issued by the Ministry of Housing and Urban-Rural Development proposes to accelerate the coordinated development of intelligent construction and industrialization of new buildings, and promote digital design, intelligent production, and intelligent construction. With the continuous progress of science and technology, the construction industry has also made many technological innovations, and innovative changes have taken place in related technologies. The residential building machine has begun to replace the traditional climbing frame application. Through gradual improvement, the lightweight building machine applicable to this project is only 220T, and the combination of spreader and building machine makes the concrete pouring process more convenient and intelligent, significantly reducing the labor intensity of construction personnel. Based on this, the analysis of the impact of mobile rail hydraulic spreader on the safety of residential building machines is a key factor.

Calculation model including time-varying coefficients for calculating the lateral pressure of bottom-up pumping self-compacting concrete

The accuracy of concrete lateral pressure predictions affects the safety and economic aspects of constructions. For the prediction of the maximum lateral pressure of bottom-up pumping self-compacting concrete, based on the graph multiplication method, a calculation model with time-varying coefficients was proposed, which considers the friction effect. The time-varying characteristics of the key coefficients of self-compacting concrete with slumps of 600 mm, 700 mm, and 800 mm were studied by simulating the concrete pouring process and, then, applied to the calculation model. In two dumbbell-shaped steel arch bridges, pressure sensors were placed in the inner wall of the typical steel pipe’s section to measure the lateral pressure during the pumping process and, hence, verify the accuracy of the calculation model. The applicability of the calculation model was verified by comparing the calculated results with other specifications. Results indicate that, as the liquid level increases, the effect of friction will cause a significant increase of pressure at the bottom. In predicting the maximum lateral pressure of bottom-up pumping self-compacting concrete, the calculation model can be well applied in the case where the liquid level was higher.

Numerical Simulation of the Construction Process of Long Spiral CFG Piles

A numerical model for the construction process of long spiral CFG piles is established based on the coupled Eulerian–Lagrangian method. The construction process is divided into drilling process and concrete pouring process for modeling. The influence of long spiral CFG piles construction on saturated sand foundation is studied, and dynamic responses, changes of pore water pressure, and void ratio of saturated sand foundation are obtained. The rationality and accuracy of the simulation results are proved by comparing with the field test data and calculation results of the theory of cylindrical cavity expansion. The presented numerical results prove that the vibration load generated during the construction acts on saturated soil in the form of irregular reciprocating shear forces, which leads to a large excess pore water pressure in the soil and an increase in soil void ratio. Both the excess pore water pressure field generated during the construction and the soil pore ratio after the construction show a parabolic distribution in the vertical direction. The research results can provide reference and theoretical basis for future research and engineering practice.

Lean construction analysis of concrete pouring process using value stream mapping and Arena based simulation model

An important challenge for the construction industry is how to reduce non-value adding activities which produce waste. Many researchers have attempted to resolve it to enhance the performance of this industry. However, the concrete pouring process (CPP) has not been adequately investigated in this regard. Accordingly, the present study aims to examine how to apply the lean manufacturing concepts to CPP effectively determine different wastes generated during operations, the main cause of the waste generation, and the strategies to minimize or mitigate the generation of the waste. Mixed value stream mapping (VSM) and computer simulation are applied to identify and eliminate wastes in a CPP case study by using lean principles and time-frame formulation through takt time calculation. Based on the future VSM improvements, findings showed that that production lead time (PLT) reduced from 11 days to 7 days, and the value-added time decreased from 38.2 min to 22.5 min. Takt time also was reduced from 138 s to 93 s. Our results are a valuable resource for construction managers and engineers to improve the concrete pouring process’s productivity in a cost-effective and timely manner.

A Positioning Method of Temperature Sensors for Monitoring Dam Global Thermal Field

During the concrete pouring process of a dam construction, timely and accurate temperature monitoring is of great significance to reveal the thermal distribution characteristics and evolution process, and control concrete cracking. In this study, a positioning method of temperature sensors (PMTS) in a concrete dam is developed to determine the arrangement of temperature sensors quantitatively. The proposed positioning method is related to the restructured thermal field based on the natural neighbor interpolation algorithm, and the cross-validation. Based on the method, thermometers, distributed optical fibers and infrared thermal imagers are optimally installed in a super-high arch dam for real-time measurement of concrete temperature. The results show that the PMTS is reasonable and reliable for obtaining the dam global thermal field. The on-site temperature monitoring data indicate that the time and space temperature distribution law of the restructured thermal field is consistent with the actual situation of the super-high arch dam. In addition, the cons and pros, and improvement of the PMTS are further discussed. The proposed PMTS is a valuable method to monitor the global thermal field of concrete dams.

Study on the safety of the concrete pouring process for the main truss arch structure in a long-span concrete-filled steel tube arch bridge

To study the safety and stability of the main truss arch structure during the concrete pouring process in a long-span CFST arch bridge, a combination of theoretical analysis and numerical simulation was adopted. The world's longest span CFST arch bridge, the Pingnan Third Bridge (main span 575 m) in Guangxi Province, was taken as an example. Firstly, the basic theory of stability and the concrete pouring technology of the main truss arch structure were summarized. Secondly, a three-dimensional finite element model of the main truss arch structure was established for the concrete pouring stage. Finally, the linearity, stress, and stability of the main truss arch structure during concrete pouring were studied. The results show that both vertical and transverse deflections occurred in the main truss arch structure during concrete pouring from the arch foot to the arch vault; the upper and transverse deflections of the main truss arch structure showed parabolic changes, and the upper and transverse deflections of the midspan section were larger than those of other sections. When concrete was poured near the 1/6 section of the main truss arch structure, the upper and transverse deflections of the middle section of the main truss arch structure peaked; the maximum upper deflection reached 113 mm, and the maximum transverse deflection reached 60 mm. In the process of concrete pouring from the arch foot to the arch vault, the stress in the steel tubes and concrete was constantly changing. Although upper and transverse deflections of the main truss arch structure occurred during concrete pouring, the stress in the steel tube and concrete in the main truss arch structure did not exceed the tensile strength, and the linearity of the main truss arch could be adjusted by retaining the anchor cables, which were set in the erection stage of the main truss arch structure at the 1/6 section of the main truss arch structure. During the concrete pouring process of the various steel tubes of the main truss arch structure, the stability coefficients of the main truss arch structures decreased gradually. During concrete pouring in a single steel tube, the maximum reduction in the stability factor was 21.32%, which occurred in the 1# steel tube, and the minimum decrease in the stability factor was 8.89%, which occurred in the 8# steel tube. The stability coefficients were greater than 4 after this reduction and met the requirements of the design specifications. This study can provide a reference for the optimization design and construction monitoring of long-span CFST arch bridges.

The Effectiveness of Sustainable Construction Materials by Using U-Shaped Composite Spacer Block (UCop)​

Nowadays in construction development, the needs of construction materials that have a unique reinforced concrete design with good quality, reasonable market price, and easy installation techniques has been prioritized. Therefore, this study aimed to produce an alternative new construction material that can fulfill the requirements. The U-shaped composite spacer block (UCop) through the production of Cement Bonded Particle Board (CBPB) as a specimen block was produced from the wood waste of carpentry work combined with Shorea spp. (Seraya red and white) particle size approximately 0.4mm - 2.00 mm. Then it was mixed together with Portland cement by using a ratio 1:2.5. The mixture was then added with Ammonia Chloride (Al2SO4) and Calcium Chloride (CaCl2) act as additives for this product. The physical and mechanical tests were conducted in this study. The results were showed that the thickness expansion was achieved an average of 1.79 %, which was passed the minimum requirement of MS934:1986 standards. However, the flexural strength did not meet the minimum standards. The poor mixing technique was attributed to the results. However, UCop still could contribute as an alternative solution in ease the concrete pouring process using a special binder, giving the spacer block any resistance to formwork of columns or beams is filled with concrete. The high-impact innovations of this product in construction such as it can help the process to be more efficient and to reduce construction costs, next indirectly preserve the nature.

Incremental extended finite element method for thermal cracking of mass concrete at early ages

Thermal cracks are cracks that commonly form at early ages in mass concrete. During the concrete pouring process, the elastic modulus changes continuously. This requires the time domain to be divided into several steps in order to solve for the temperature, stress, and displacement of the concrete. Numerical simulations of thermal crack propagation in concrete are more difficult at early ages. To solve this problem, this study divides crack propagation in concrete at early ages into two cases: the case in which cracks do not propagate but the elastic modulus of the concrete changes and the case in which cracks propagate at a certain time. This paper provides computational models for these two cases by integrating the characteristics of the extended finite element algorithm, compiles the corresponding computational programs, and verifies the accuracy of the proposed model using numerical comparisons. The model presented in this paper has the advantages of high computational accuracy and stable results in resolving thermal cracking and its propagation in concrete at early ages.

Incremental extended finite element method for thermal cracking of mass concrete at early ages

Thermal cracks are cracks that commonly form at early ages in mass concrete. During the concrete pouring process, the elastic modulus changes continuously. This requires the time domain to be divided into several steps in order to solve for the temperature, stress, and displacement of the concrete. Numerical simulations of thermal crack propagation in concrete are more difficult at early ages. To solve this problem, this study divides crack propagation in concrete at early ages into two cases: the case in which cracks do not propagate but the elastic modulus of the concrete changes and the case in which cracks propagate at a certain time. This paper provides computational models for these two cases by integrating the characteristics of the extended finite element algorithm, compiles the corresponding computational programs, and verifies the accuracy of the proposed model using numerical comparisons. The model presented in this paper has the advantages of high computational accuracy and stable results in resolving thermal cracking and its propagation in concrete at early ages.

Study on mechanical properties of a new type of prefabricated GRC mold shell

The GRC formwork structural column adopts the factory-based vertical prefabrication production process, which can reduce the floor space, reduce the formwork loss, speed up the construction progress, promote the full decoration of the prefabricated building, and improve the efficiency of the assembly construction. major. In order to optimize the production process of prefabricated GRC formwork column, the overall stress system of GRC formwork structure is analyzed in the concrete pouring process, and the thickness of GRC formwork, the number of steel hoops and the GRC mode are considered. The influence of the shell cross-section size on the mechanical properties. The research results can provide reference for the optimization and design of prefabricated GRC formwork column production process.

Study on stress simulation of concrete floor on transversely isotropic equivalent pile foundation during construction period

In the concrete pouring process of large pumping stations, the pile foundation plays an important role in supporting the upper structures, and also has a certain constraint on the concrete floor. In the numerical simulation calculation of construction period, to simplify the pre-processing, the volume ratio method is sometimes applied to regard the pile and surrounding soil foundation as the equivalent pile foundation, while the anisotropy of pile foundation is ignored, which will result in large calculation error of the horizontal stress of the concrete floor. Aiming at this problem, the anisotropy theory of materials is adopted in this paper to simulate the temperature field and stress field of the concrete floor both on non-equivalent pile foundation and equivalent pile foundation during construction period after compiling corresponding calculation program. The results show that when the ratio α of the horizontal elastic modulus to the vertical elastic modulus of equivalent pile foundation is about 1/20, the calculation result of the transversely isotropic equivalent pile foundation is approximately equal to the calculation result of the non-equivalent pile foundation (exact solution). It may provide some reference to similar engineering numerical simulation.

Design and Analysis of a Concrete Placer for Optimize the Craft of Infilled Walls’S Constructional Column

Aiming at the construction of infill wall structural column are often used in artificial layer pouring method and top pouring back method, to improve the structure of wall column concrete pouring process, puts forward a new type of structural column concrete pouring machine. The application of this equipment, process worker can finish pouring filled wall structure column and tap filled wall structure column and unloading modulus. Reduces the labor intensity, reduces the construction cost and ensure the construction quality of frame pillar structure, realizes the structural column placement by artificial into mechanization. Introduces the design concept and the design of machinery equipment. Put forward a kind of "mixed Vibration, Lifting and Transmission" design concept. The mechanical design including a pumping device, transmission device, track lifting device, transmission device, vibration device, supporting steel template module six. Describes the structure and function of the main components of the. Describes the use of the method and the working principle of the equipment. And correlation analysis and calculation on the key parts. Presents the control principle and control calculation. Through the 3D MAX animation simulation and real structures is feasible

Finite Element Analysis on Temperature Field of Inorganic Polymer Concrete Pouring Process

Because of its remarkable advantages, inorganic polymer concrete has been paid much attention by academic and engineering field in recent years. On the basis of inorganic polymer concrete temperature-stress test, the temperature field of concrete pouring process is simulated by using the finite element software ANSYS. The related thermodynamic properties of inorganic polymer concrete are discussed. Studies have shown that the temperature-time curve of inorganic polymer concrete pouring process has the same trend with that of the normal concrete. Temperature contours show a ring-shaped distribution. When the internal temperature of specimen reaches the peak, the center temperature is 44.947 degrees Celsius and the surface is 22.216 degrees Celsius. The results have certain value to explore the early cracking of inorganic polymer concrete.

Performance Improvement of Concrete Pouring Process Based Resource Utilization Using Taguchi Method and Computer Simulation

One of the most controversial issues in construction management is performance measurement. Construction managers are always involved in evaluation of resource changes which effect process performance. Due to limitations and also cost of resources, resource allocation has become a complex task in construction projects. To evaluate the effects of different resources on total project performance, managers strive to allocate limited resources by determining resource combinations. This paper aims at conducting Taguchi method along with computer simulation to determine the optimum combination of resources for a real world case study involving a concrete pouring operation in order to reduce cycle time and process costs. The proposed simulation model was conducted under Arena 13.9. Final result shows that the optimum resource combination will be achieved when all of resources are located in the low level. This means that number of trucks, spreader crew, vibrator crew and finisher crew should be equal to 3, 1, 1, and 1 respectively to improve the total performance.

Predicting the Duration of Concrete Operations Via Artificial Neural Network and by Focusing on Supply Chain Parameters

Abstract Being able to precisely predict the duration of concrete operations can help construction managers to organize sites and machineries more efficiently, especially when there is limited space for equipment on site. Currently there is no theoretical method for estimating the duration of the concrete pouring process. Normally, the maximum capacity of pumping facilities on construction sites is not used, and concrete pumps are idle for a considerable time as a result of the arrival of concrete trucks being delayed. In the light of this issue, this paper considers the supply chain parameters of Ready Mixed Concrete (RMC) as a means of solving this problem. Artificial Neural Network (ANN) is hired for modelling/predicting the productivity of a concrete operation. The proposed model is tested with a real database of an RMC in the Sydney metropolitan area that has 17 depots and around 200 trucks. Results show that there is an improvement in the achieved results when these are compared to the results of relevant studies that only considered the construction parameters for predicting the productivity of concrete operations

Exterior-Template Design for Concrete Engineering in an Arched Structure

In accordance with the technical specifications of existing concrete structure construction template and an arched structure concrete pouring process, the exterior-template design for concrete of the project has been done, which contents the requirements of the of engineering concrete on construction quality.