Concrete Foundation Research Articles

Research on Temperature Control of Mass Concrete of Fan Foundation

In recent years, wind power, as a new energy source, has its unique advantages. Under the push of the country, the number of wind power plants is increasing. Based on a wind power plant project in Shanxi Province, temperature field simulation is carried out for the construction of large volume concrete fan foundation, and field temperature monitoring and early acoustic emission monitoring experiments are carried out. The development trend of the temperature field inside the mass concrete is obtained, which reflects the temperature change inside the foundation in real time, and the rule between temperature and acoustic emission signal is found, which plays a certain guiding significance for the construction of mass concrete.

BEARING CAPACITY OF SHALLOW FOOTINGS RESTING ON DUNE SAND

As a result of the growth of economic, demographic and building activities in Iraq, that necessitates carrying out geotechnical investigations for the dune sand to study behavior of footings resting on these soils. To determine these properties and to assess the suitability of these materials for resting shallow foundation on it, an extensive laboratory testing program was carried out. Chemical tests were carried out to evaluate any possible effects of the mineralogical composition of the soil on behavior of foundation rested on dune sands.Collapse tests were also conducted to trace any collapse potential. Loading tests were carried out for optimum water content and different shapes of footing. Loading test recommends manufacturing of steel box and footing models with different shapes and dimensions. The results indicated that, Affek dune sand is predominantly fine sand with non-plastic fines.Because the content of sulphate (as SO3) is only 0.05%, and the alkalinity of dune sand, which reduces the corrosion potential, ordinary Portland cement can be used in concrete foundation construction in/on dune sands. The results of collapsing tests showed that Affek dune sand exhibit a slight to moderate potential depending on stress level. Due to Soaking by water, the reduction in bearing capacity of optimum state was about 45%. The bearing capacity of square footing was greater than those of the circular and rectangular footings.

Study of a monopile with pre-tensioned tethers for offshore wind turbines at deeper waters

Currently, monopiles are the industry's first choice to support offshore wind turbines (OWTs) due to the complexities associated with fabrication, transportation and installation of various foundation solutions. These are, however, considered suitable for water depths up to ∼30–35 m, beyond which they become massive and complex to handle. Increasing the application range of monopiles without making them too large by adopting some suitable means may significantly impact the rapid growth of OWTs at intermediate water depths (∼50 m), where existing solutions such as jackets or concrete gravity foundations involve large capital expenditure. In this work, a novel approach of utilising pre-tensioned tethers along with a 6.0 m wide monopile was explored for 50 m water depth. Under an extreme load case, the stress ratio was found to be reduced from 1.17 to 0.44 when pre-tensioned tethers are used. Similarly, it was found that by adjusting parameters associated with the proposed concept, fatigue damage can be brought down from a very high value to 0.63 or less. The results thus show that the proposed approach can open new avenues to bring competitiveness to the cost of offshore wind energy at intermediate water depths.

In silico curation of QTL-rich clusters and candidate gene identification for plant height of bread wheat

Many genetic loci for wheat plant height (PH) have been reported, and 26 dwarfing genes have been catalogued. To identify major and stable genetic loci for PH, here we thoroughly summarized these functionally or genetic verified dwarfing loci from QTL linkage analysis and genome-wide association study published from 2003 to 2022. A total of 332 QTL, 270 GWAS loci and 83 genes for PH were integrated onto chromosomes according to their locations in the IWGSC RefSeq v2.1 and 65 QTL-rich clusters (QRC) were defined. Candidate genes in each QRC were predicted based on IWGSC Annotation v2.1 and the information on functional validation of homologous genes in other species. A total of 38 candidate genes were predicted for 65 QRC including three GA2ox genes in QRC-4B-IV, QRC-5A-VIII and QRC-6A-II (Rht24) as well as GA 20-oxidase 2 (TaSD1-3A) in QRC-3A-IV. These outcomes lay concrete foundations for map-based cloning of wheat dwarfing genes and application in breeding.

Insulated concrete form foundation wall as solar thermal energy storage for Cold-Climate building heating system

Employing green energies for building energy sector decarbonization has captured the world’s attention in the current century. However, the imbalance between energy demand and availability necessitates designing reliable and cost-effective energy storage systems. The present study aims to propose an innovative building-integrated solar thermal storage method using insulated concrete form (ICF) foundation walls for residential buildings in cold climates such as that of Canada. Surplus solar thermal energy is stored inside the ICF wall, which has a high thermal capacity and mass and is integrated into the building envelope. The ICF wall and solar thermal collectors are coupled with a water-to-water heat pump to meet building space heating load and domestic hot water demand. Different configurations integrating the ICF wall are modeled and simulated in TRNSYS software to perform a yearly transient analysis. It is shown that a system with ICF walls has an 11% higher solar fraction (SF) than a similar system with a large water thermal storage tank. By replacing the solar thermal collector with a hybrid photovoltaic/thermal collector, the overall system solar fraction can increase to 20% above that of a similar system with a large water thermal storage tank system. An ICF-based system with a 16 m2 solar collector can completely cover nine months of space heating and domestic hot water load for a single-family house in London, Ontario. A detailed sensitivity analysis shows that the proposed ICF-based systems achieve an optimum solar fraction at high tilt angles (65-70°), unlike a similar design with an extensive water thermal storage tank system. Because of their ability to achieve a high SF at high tilt angles, ICF systems are suitable for vertically mounted solar systems typically required by high-rise buildings due to limited roof area. As part of the building envelope, ICF foundation walls have no additional cost and can be considered a feasible strategy for reducing the residential sector’s carbon footprint..

Numerical Simulation Research on Vibration Isolation Performance of Concrete Foundation Platform

The simulation analysis model of the concrete experimental foundation platform is constructed by the method of three-dimensional computer-aided design (3D CAD) and three-dimensional computer-aided engineering (3D CAE). The influence of the slotting depth and width on the concrete structure’s vibration isolation performance is analyzed in detail. The results show that as the slotting depth increases from 0 m to 4 m, the total vibration acceleration level of the concrete inner side structure decreases by 12.27 dB. The vibration isolation performance of the foundation platform is highly sensitive to the slotting depth. As the slotting width increases from 0.5 m to 2 m, the total vibration acceleration level of the concrete inner side structure is always maintained within the range of 8.8 dB–8.9 dB. The total vibration acceleration level of the foundation platform changes little. Vibration isolation performance shows low sensitivity to the slotting width.

경년변화에 따른 콘크리트 매입 기초접지극의 접지저항 특성분석

In accordance with the Korea Electro-technical Code(KEC), which took effect on January 1, 2021, concrete foundation rebar can be newly applied as a type of ground electrode. Using the foundation rebar of a building as a ground electrode is economically advantageous because it does not require additional grounding equipment and the structure of a typical building (rebar and steel H-beam) is easy to maintain electrical continuity. Because of these advantages, more and more building foundation rebar are being used as ground poles in actual construction.In this paper, the characteristics of grounding resistance over time when using these concrete foundation rebar as grounding electrodes in construction sites were analyzed. To this end, we proposed a plan to connect ground wires to concrete foundation rebar in two buildings under construction to measure and analyze the grounding resistance of the building over time for about four months and apply ground poles to the actual site.

Investigation of Load-Bearing Capacity for Reinforced Concrete Foundation Retrofitted Using Steel Strut–Tie Retrofit System

To reduce the thickness of reinforced concrete foundation members used in construction and structural applications, a previous study developed and tested a strut–tie retrofit system installed in the foundations. This study proposes the optimum retrofit details of a steel-tie retrofit system for foundation members with reduced thickness via a finite element simulation-based load-bearing capacity assessment. The retrofit parameters (structural steel type, plate thickness, and number of strut frames) that significantly affected the load-bearing capacities were optimized by comparing the maximum effective stress and code-defined allowable stress limits. The optimum retrofit details were compared with those computed using a code-defined strut–tie model. Based on the load-bearing capacity assessment for the design of loading combinations, the optimum retrofit details can be reduced in transverse (by 55%) and longitudinal (by 87%) directions compared with those designed using the strut–tie model approach.

Analysis of bridge foundation pile detection based on convolutional neural network model

Abstract In order to quickly and accurately detect the instability of foundation piles on concrete Bridges, an improved convolutional neural network based image recognition method for concrete bridge pile foundations was proposed. In order to improve the image quality, the entropy threshold method is used to process the image, and the two-channel convolutional neural network is designed to extract the image features fully. The improved traditional Relu activation function avoids model underfitting. Support vector machine (SVM) was used to replace Softmax classifier to improve computing efficiency. The experiment of bridge pile foundation image recognition shows that the improved convolutional neural network has significantly improved the recognition rate of the real bridge pile foundation. No matter how many degrees the image is rotated, the method in this article always maintains a high recognition rate, and the recognition rate does not fluctuate much, indicating that the algorithm in this article has good robustness to rotation and translation. In summary, the average recognition rate of the 5 groups was 96.26%. The feasibility of this method in identifying bridge pile foundation is proved.

A systematic review – handwritten examinations are becoming outdated, is it time to change to typed examinations in our assessment policy?

With the advances of technologies, possessing digital and information literacy is crucial for the selection of candidates by employers in this digital AI era. For most students, receiving and outputting electronic text has become the norm, and thus examinations with writing components done by hand may not accurately reflect their abilities. It seems that such traditional handwritten examinations are incongruous when assignments are now expected to be in typed formats, so the question is should it become part of the university assessment policy to make it compulsory for students to type their examinations? To better assist higher education institutions in planning for long-term, future-oriented assessment policies, this study provides a systematic review of the literature focusing on typed and handwritten examinations. A classification scheme of the unambiguous advantages and disadvantages, ambivalent factors, and impacts and perceptions for different stakeholders, is developed based on the findings to provide a thorough and concrete foundation for stakeholders to act upon and navigate the complexities of transitioning to typed examinations.

Dynamic Analysis of CRTS II Ballastless Track-Vehicle System Based on Moving Unit Method

On account of the influence of the discontinuity of CRTS II ballastless track slabs and the discrete support of track pads on the high-speed rail vehicle-ballastless track system, a vibration analysis calculation model of the ballastless track-vehicle coupling system was established on the basis of the moving unit method. The dynamic response of the system at different travel speeds and with and without consideration of the track plate discontinuities was investigated. The effect of the random process discontinuity on the dynamic response of the steel rails was analyzed by Fourier inverse transform on the high and low discontinuity spectra of ballastless rails on China’s high-speed rail. We also generated time domain samples of the track discontinuity corresponding to the three percentile spectra. The results show that the dynamic response of the track structure increases with the speed of the train under the condition of track unevenness, with the dynamic response of the steel rail being the most significant, while the dynamic response of the track slab and concrete foundation decreases step by step compared with that of the steel rail; the discontinuity of the track slab has a low impact on the vertical acceleration of the vehicle and does not affect the smoothness of the train; the magnitude of the dynamic response of the rail increases as the amplitude of the irregularities increases or the wavelength decreases. In the wavelength of 2~30 m, the maximum and as the wavelength of the discontinuity sample increases, the oscillation of the power response time curve decreases significantly and tends to be smooth.

Thermal modeling and monitoring of massive concrete foundations to prevent pathological manifestations

Thermal modeling and monitoring of massive concrete foundations to prevent pathological manifestations

Digital reconstruction of a concrete pile from temperature data and boundary element formulation

This paper presents an application of the boundary element method (BEM) in engineering to numerically analyse the integrity of cast-in-place concrete foundations, as in the case of concrete piles, using a developed system composed of an artificial heat source, thermometers coupled with metal reinforcement and mathematical algorithms. This type of integrity monitoring of concrete piles is present in recent articles where temperature measurements occur only during the cement curing process, related to the cement hydration reaction in a time interval of a few days. However, the innovation proposed in this study refers to the possibility of continuous monitoring of the pile, considering the installation of an artificial heat source, whose temperature measurements will allow evaluating the positioning of the metal reinforcement inside the pile, in order to identify possible concreting anomalies and/or exposure of metal rods to the ground, where metal corrosion can be more pronounced. The diffusion equation with heat generation and the D-BEM formulation is used to simulate a cross-section of the set of soil and concrete pile with metal reinforcement in different situations. Details on the formulation of boundary elements used, as well as numerical results on the feasibility of the methodology developed to monitor the integrity of cast-in-place concrete foundations, are presented below.

How have the land reform, misunderstanding, and dysfunction of modernity led to rural underdevelopment in Iran?

Rural underdevelopment in Iran has triggered numerous theoretical standpoints and discussions. However, none of them are based on concrete scientific foundations and historical arguments. The literature contains little or no evidence to support or refute that rural underdevelopment in Iran has originated in modernity. Accordingly, the present historical study mainly aimed to explore the role of modernity in Iranian rural underdevelopment. So, around 500 secondary documents including books, articles, and journals published from 1906 to 2019 were reviewed and coded. The research team needed a general comprehension of the course of events, so the researchers adopted the systems thinking approach and dynamic systems method to fulfill the research objective, i.e., obtaining a general comprehension of the studied events. The investigation of the historical events in Iran showed that the misunderstanding of modernity in Iran led to dysfunction, which resulted in making inefficient decisions, such as land reform. This trend has continued until today and led to rural underdevelopment. Since the theory of modernization is still supported and applied in Iran, fundamental changes are needed in policymakers’ and government officials’ perceptions of modernity. This means a shift in the role of government in the implementation of modernity programs, including land reform, from a dominant and implementing agent to a supporting agent. This perspective can be more practical and efficient than making efforts to force changes. Executive officials can first focus on conceptual changes like changing social and cultural contexts towards modernization. Furthermore, this finding can explain the causes of the success and failure of modernization in rural areas of developing countries. Finally, the results can serve as a preliminary analysis for building a framework to give development theoreticians access to information about rural underdevelopment in Iran. Overall, the policy implications of the study could be far-reaching, not least because they may force planners to change their attitudes toward theoretical standpoints in Iranian rural development.

Casting plan for a mass concrete foundation of a high-rise building for avoiding DEF and shrinkage cracking

Casting plan for a mass concrete foundation of a high-rise building for avoiding DEF and shrinkage cracking

Analysis of the Effect of Protective Properties of Concretes with Similar Composition on the Corrosion Rate of Reinforcing Steel Induced by Chloride Ions.

This study presents a comparison of the protective properties of three concretes of similar composition on the effect of chloride ions. To determine these properties, the values of the diffusion and migration coefficients of chloride ions in concrete were determined using both standard methods and the thermodynamic ion migration model. We tested a comprehensive method for checking the protective properties of concrete against chlorides. This method can not only be used in various concretes, even those with only small differences in composition, but also in concretes with various types of admixtures and additives, such as PVA fibers. The research was carried out to address the needs of a manufacturer of prefabricated concrete foundations. The aim was to find a cheap and effective method of sealing the concrete produced by the manufacturer in order to carry out projects in coastal areas. Earlier diffusion studies showed good performance when replacing ordinary CEM I cement with metallurgical cement. The corrosion rates of the reinforcing steel in these concretes were also compared using the following electrochemical methods: linear polarization and impedance spectroscopy. The porosities of these concretes, determined using X-ray computed tomography for pore-related characterization, were also compared. Changes in the phase composition of corrosion products occurring in the steel-concrete contact zone were compared using scanning electron microscopy with a micro-area chemical analysis capability, in addition to X-ray microdiffraction, to study the microstructure changes. Concrete with CEM III cement was the most resistant to chloride ingress and therefore provided the longest period of protection against chloride-initiated corrosion. The least resistant was concrete with CEM I, for which, after two 7-day cycles of chloride migration in the electric field, steel corrosion started. The additional use of a sealing admixture can cause a local increase in the volume of pores in the concrete, and at the same time, a local weakening of the concrete structure. Concrete with CEM I was characterized as having the highest porosity at 140.537 pores, whereas concrete with CEM III (characterized by lower porosity) had 123.015 pores. Concrete with sealing admixture, with the same open porosity, had the highest number of pores, at 174.880. According to the findings of this study, and using a computed tomography method, concrete with CEM III showed the most uniform distribution of pores of different volumes, and had the lowest total number of pores.

Ensuring the Serviceability of 0.4 kV Electric Networks in Case of Breaks of the Combined Neutral and Earth Conductor

Breaks of the neutral conductor are among the most common failures in 0.4 kV networks. At present, to ensure the electrical safety of personnel, grounding loops with standard values of grounding resistance in compliance with Electrical Installation Code (PUE) are set up. Such grounding loops do not have any significant impact on the power quality indicators. Moreover, their construction is quite expensive and requires significant material costs. To maintain power quality parameters within the permissible limits, grounding loops with much lower resistance values are needed, which, however, are much more expensive. One of the ways for solving the problem under consideration is the use of natural grounding conductors for temporarily maintaining the standard electric power quality. The article addresses the problem of ensuring the electric power quality in case of breaks of the neutral conductor and a decrease of its conductance with reference to voltage unbalance. The ways of solving this problem are briefly outlined, in particular, by laying an additional conductor or using the TN-C-S grounding system. One of the alternative solutions to the problem considered is the use of natural grounding conductors, for example, a reinforced concrete foundation or a metal fence. The grounding resistances of such grounding conductors were calculated, the estimated values of which have confirmed the possibility of using them to comply with the PUE requirements. Practical recommendations for implementing the suggested proposals are given. One of them is to develop a device for monitoring the state of the neutral protective and main conductors. The key related issue of the problem considered is to ensure the electrical safety of both personnel and all people staying in the territory in which the grounding is temporarily used as the main neutral conductor. This issue will be addressed in the subsequent publications.

Gelam Wood (Melaleuca cajuputi Powell) as a Substructure Construction Material

Gelam wood (Melaleuca cajuputi Powell) which is widely used for substructure construction materials in South Kalimantan is classified into strong class II and durable wood class III. This study aims to provide more detailed information regarding what forms of use of gelam wood as substructure construction material and why gelam wood was chosen for it. This information will later be able to support the preparation of future utilization plans for the use of gelam wood considering that currently gelam wood is starting to decrease in availability. The method to identified the use of gelam wood as a substructure construction material is field survey method combine with other references. Gelam wood with a large diameter of 10-12 cm and a length of 4 m is generally used as a construction foundation for 1-storey building with an ultimate bearing capacity of 729,25 kg for single pile foundation. In terms of cost, the foundation with gelam wood material is cheaper than the mini-pile concrete foundation for the construction of the same building. The large size of gelam wood is also used as sheet pile or retaining wall with an average flexural strength of 100,13 MPa. The small size of gelam wood is generally used as wooden scaffolding where the cost of gelam wood scaffolding is 26.85% cheaper than iron scaffolding in the rental price, and 15 times the cost of the iron scaffold in the purchase price.

Selection of foundation type of hospital building using analytical hierarchy process

In order to develop the Ministry of Defense Hospital dr. Suyoto in Bintaro, South Jakarta, a new 27-storey building will be built on the south side of the hospital complex. This study aims to select the type of foundation that is able to support the building above it, but with minimal disturbance due to vibration, noise, mud, and excavation, because the hospital must continue to operate, and relates to aspects of cost, time, and scope. The method used is the Analytical Hierarchy Process (AHP) involving five respondents who are considered construction experts from the Construction Center (Puskon) officers, planning consultants, supervisory consultants, and contractors. The results of the study found that concrete pile foundations with Hydraulic Static Pile Drivers (HSPD) were the most suitable for new building foundations from the five criteria and four alternative choices of foundations. In the detailed design process by the planning consultant, several pile caps were found that coincide with each other so it was decided to combine them into a large pile cap which also functions as a raft foundation. So that in its implementation, a combination of concrete piles with HSPD and raft foundations is used.

Георадарные обследования горнотехнических сооружений западной части Арктики

The application of georadar surveys is described as a non-destructive, giving a detailed continuous (profile) picture, method for studying the internal structure and water saturation of mining structures. Examples of surveys of specific objects of large mining enterprises in the western part of the Arctic are given. It is shown that the electromagnetic field induced by the georadar is distorted in areas where the physical properties of rocks and soils differ (heterogeneities, increased fracturing, tectonic disturbances, faults, zones of increased water saturation, etc.). The key parameter of georadar sounding is determined, which is the intensity of wave field distortion, determined by the contrast (ratio) of the physical properties of rocks, spatial orientation and depth of heterogeneity. Based on this, structural features of the rocks of the Zhelezny quarry JSC “Kovdorsky GOK”, the mine Vostochny KF of JSC «Apatit», etc. were revealed. Hidden tectonic faults and heterogeneities of the massif, which pose a potential danger to mining operations and industrial facilities, were identified and traced. On the basis of long-term monitoring georadar surveys of the enclosing dams of the tailings of Kovdorsky GOK JSC, Kola Mining and Metallurgical Plant JSC, Oleniy Ruchey Mining and Processing Complex of NWPC, OLCON JSC, patterns of formation of filtration-deformation processes were established. For the Oleniy Ruchey mine, quality assessments were made for the construction of tailings dams, concrete foundations for mills, and railway loading and unloading terminals. On the island of Svalbard, georadar surveys have clarified the upper boundary of frozen rocks under the site of the thermal power plant of Arktikugol JSC.