Behavior of Steel Fiber Reinforced Concrete Panels under Surface Pressure

In this study, it is aimed to investigate the importance of the affecting parameters on the pressure–displacement relationship of steel fiber reinforced concrete panels. Among these parameters, panel thickness, panel dimensions, material type, and boundary conditions of the panels are the parameters that were examined. In this context, the effects of surface pressure on the steel fiber reinforced concrete panels were investigated. It was observed that as the thickness and the fiber ratio increased, the ultimate bearing capacity increased. It was determined that it may not be enough to support the panels only at the corner points, and intermediate supports are needed. As the support spacing decreased, the absorbed surface pressure increased. In addition, it was concluded that the increase in the amount of steel fiber in the concrete material increased the strength, deflection, and ductility values.

Improving the dependability of light vented foundations exposed to vibration load on frost soils

Aim. Today, dynamically-loaded foundations of process equipment often prove to be oversized with significantly overestimated values of stiffness, mass and material consumption. Therefore, reducing the costs and time of construction of gas pipeline facilities, especially on permafrost, is of relevance to PJSC Gazprom. One of the primary ways of solving this problem is installing gas pumping equipment on light vented support structures. The disadvantage of such structures is the low vibration rigidity. A method [1] is proposed for improving the vibration rigidity of a foundation subjected to vibration load. The simulation aims to improve the dependability of light vented foundations by studying vibration displacements of foundations with attached reinforced concrete panels depending on the thermal state of frost soils, parameters of the attached panels and connectors. Methods. Vibration displacements of a foundation with an attached device were identified using the finite element method and the improved computational model of the foundation – GCU – soil system. Results. Computational experiments identified the vibration displacements of the foundation in the cold and warm seasons for the following cases of reinforced concrete plates attached to the foundation: symmetrical and non-symmetrical; at different distances; through connectors with different stiffness parameters; with additional weights; frozen to the ground. Conclusions were made based on the results of simulation of vibration displacements of foundations with an attached device in cold and warm seasons. Conclusion. The presented results of computational experiments aimed at improving the vibration rigidity of light foundations by using method [1] show sufficiently good indicators of reduced vibration displacements of the foundation. Thus, in the case of symmetrical connection of four reinforced concrete panels in summer, the reduction of vibration displacements is 42.4%, while increased stiffness of the connectors, attachment of additional weights and freezing of reinforced concrete panels into the ground will allow reducing the vibration displacements of the foundation up to 2.5 times. However, it should be noted, that applying the findings in the process of development of project documentation and construction of foundations requires R&D activities involving verification and comparison of the obtained results of numerical simulation with a natural experiment.

Experimental and Numerical Studies on the Behaviors of Autoclaved Aerated Concrete Panels with Insulation Boards Subjected to Wind Loading

Autoclaved aerated concrete panels (AACP) are lightweight elements in civil engineering design. In this paper, experiments and numerical analyses were conducted to study the flexural behavior of an enclosure system that consisted of AACPs and a decorative plate. A full-scale test was conducted to investigate the behavior of the enclosure system under wind suction. Load–deflection curves and load–strain relationships under different wind pressures were recorded and discussed. The effects of thickness, reinforcement ratio, and strength grade on the flexural behavior of AACPs were numerically investigated. Based on the numerical results, we found that the flexural behavior of AACPs can be improved by increasing the thickness or the reinforcement ratio. A comparison of finite element and theoretical results calculated using American and Chinese design formulae was conducted, and the results indicated the existing design formulae can conservatively estimate the major mechanical indices of AACPs.

Visible Corrosion Damage in Carbonated Reinforced Concrete

This study discusses visible corrosion damage due to carbonation in concrete balconies and facades. The focus of the study was to find out how the age of the structure, cover depth of concrete, carbonation coefficient, capillarity of concrete and the climate affect visible corrosion damage. The research data consist of condition investigation reports of existing concrete balconies and facades built between 1948 and 1996. Balcony slabs and brushed painted facades were the most prone to visible corrosion damage. None of the researched panels met the required minimum cover depth of reinforcement even at the time of construction. However, most of the visible damage on the database was localized damage and there was not much visible corrosion damage. The carbonation coefficient of balconies was higher than the carbonation coefficient of facades. Brushed painted facade panels had clearly higher carbonation coefficient than other facade panels. The carbonation coefficient was considerably lower on white concrete panels compared to other panel types. When capillarity of concrete raises, the carbonation rate of concrete increases slightly. However, no correlation can be seen. The capillarity of concrete and the carbonation rate of concrete had a major range.

Impact identification on concrete panels using a surface-bonded smart piezoelectric module system

Timely identification of collision damage, especially in aging bridges, is critical for the safety of commuters. However, there is no efficient, cost-effective, in-situ technique to serve this purpose. Wave propagation-based structural health monitoring (SHM) using piezoelectric material is a promising alternative for remote sensing. To that end, this study aims to develop a wave propagation-based monitoring technique using surface-bonded smart piezoelectric modules (SPM) to determine the impact force, location, and projectile properties of low-velocity impacts on concrete panels. An impact source localization algorithm used in composite structures is adapted and simplified for concrete structures. This technique is validated using a combined experimental and numerical investigation, which shows good agreement with the actual impact source location. The impact force, projectile mass, and velocity is determined using a semi-theoretical-experimental technique based on Reed contact model. A special contact-SPM is fabricated and calibrated to determine the contact force at the impact location. The relationship between contact-SPM response and distributed-SPM response is determined using a drop-weight test with steel sphere. The peak contact force and contact duration are in good agreement with Reed contact model, although the latter overpredicts the given parameters. A simplified formula based on Reed contact model is used to inversely estimate the projectile velocity of a known mass and vice versa. Then, using pre-calibrated data, the impact force, projectile properties, and impact force-time distribution is determined using the response of distributed-SPM system. The technique is validated using an arbitrary steel sphere mass. As demonstrated in the combined experimental, theoretical, and numerical study, the proposed surface-bonded SPM system is capable of effectively identifying low-velocity impact incidents on concrete structures, which could potentially facilitate inexpensive, in-situ, real-time condition assessment.

Investigation of Fire Effect of Reinforced Aerated Wall (ACC) System Produced by Using Sustainable Construction Material

Reinforced Aerated Concrete panel building systems are preferred as wall elements in residences and industrial facilities due to their advantages. The signal issue encountered in industrial facilities is caused by fires that occur. Fire resistance of sustainably reinforced aerated concrete panels was investigated. The wall G3/05 class reinforced panel model to be used for the test was preferred. The panel wall has been subjected to a 120-minute fire resistance test. In this process, 1050 C° temperature was measured on the surface exposed to flames, while the wall temperature was read 50 C° on the other surface, and the heat temperature increased to 70 C° only at the panel joints. The data obtained from showed that the reinforced aerated concrete panels maintain their integrity under fire and resistant to high temperatures. These data that reinforced aerated concrete systems should be preferred, in buildings with human population and high fire risk.