Current Issue : October-December Volume : 2024 Issue Number : 4 Articles : 5 Articles
This study establishes a numerical model for beam-type steel–concrete composite specimens considering the corrosion of anchor bolts, with which studies the long-term deformation performance of the components under sustained load. The experimental results were compared with the calculated values obtained by combining the effective modulus method according to the CEB-FIP 1990 code and the ACI 209R code. Then a comparison with the calculation method of shrinkage and creep in standards (Standard Creep Method (SCM)) is made, and it shows that by supplementing the degradation of interface stiffness due to corrosion (using the defined modulus method (DMM)), the simulation results match better with the experimental results, confirming that this approach is suitable for analyzing the long-term load conditions of anchor bolt corrosion. Furthermore, based on the defined modulus method, the long-term behavior of composite beams under different loads and varying corrosion rates is studied....
The accurate installation of long-span arch bridges’ arch ribs remains a challenge due to the complex calculations required for cable forces and arch rib displacements, as well as the significant influence of environmental and construction loads. In this study, we propose a practical approach to alignment and error feedback control for long-span arch bridges. Cable forces were optimized using multiple control objectives based on influence matrix principles. The impact of temperature on the next segment to be installed was analyzed using the metastatic GM(1, 1) model and fitting results. Several tunable parameters were employed to account for parameter errors and environmental interference. These parameters were adjusted based on the deviations between practical and theoretical alignments for different arch rib segments, achieving a model output of an offset-free-tracking arch rib structure. This technology was applied to monitor the construction of the Tian’e Longtan Grand Bridge. Compared to conventional alignment control approaches, the proposed method achieved excellent arch ring alignment after the closure of the high-accuracy arch rib and cable release, as well as effective control of cable force uniformity and tower deviation. Field measurement data indicate that the closing deviation of the arch ring is only 3 mm. This study provides a valuable reference for the construction control of long-span arch bridges....
The tabular roof construction method (TRcM) is an alternative to open-cut and cover tunnels commonly used in constructing underground structures. The open-cut tunnels often lead to traffic congestion and ground settlement, especially in densely populated areas. However, when dealing with very soft ground that allows minimal settlement, piling becomes necessary to distribute the load. Implementing ground improvement solutions in such scenarios poses challenges in terms of space and time constraints. This study presents a unique case study that explores the combination of helical piles with the TRcM, offering a viable solution for ground improvement under challenging ground, limited space, and time constraint conditions. A robust helical pile loading system design for static compression tests inside TRcM ensuring TRcM pipe stability is presented. Also, the validation of the helical pile-bearing capacity interpretation using various factors through static field test inside the TRcM is presented....
The incorporation of sisal fiber into the concrete matrix reduces waste disposal, which has negative environmental impacts. The aim of this study was to perform an experimental investigation on shear strength and microstructure of chemically treated sisal fiber-reinforced concrete (SFRC). In order to accomplish the aim of the study, physical, shear, and mechanical properties of concrete reinforced with chemically treated sisal fiber have been performed. 0.50%, 1.00%, 1.25%, 1.50%, 1.75%, and 2.00% of sodium hydroxide (NaOH) and sulfuric acid (H2SO4) treated sisal fiber were used as an addition to the dry weight average with the help of the American Concrete Institute (ACI) mix design procedure. After the 7th and 28th days of curing, shear strength according to the ASTM D5379M standard and the mechanical properties of concrete have been conducted. For microstructural properties, scanning electron microscopy (SEM) and X-ray diffraction (XRD) were conducted after the concrete was cured for 28 days. Forty-six percent and 20% compressive strength enhancement at the 7th and 28th days of curing was compared to the control mix. Twenty-seven percent enhancement was recorded in the split tensile strength of 1.5% SFRC as compared to the control mix at 28 curing days. A shear strength of 1.5% SFRC was improved by 95% at the 7th curing days and 28% at the 28th curing days as compared to the control mix. As compared to conventional concrete, SFRC shows a denser microstructure. In addition to this, portlandite, quartz, calcium aluminum silicate, and C─S─H crystal are the available phases in the concrete matrix....
Energy demand is continuously increasing around the globe, and the building sector contributes 40% of the total energy consumption, as per the studies. Fossil fuels are the primary cause of harmful gas emissions, thus causing environmental pollution. There is a dire need to introduce innovative techniques to fulfill energy demands while reducing environmental pollution. Phase change materials (PCMs) are the latent thermal storage materials that store thermal energy during phase change from solid to liquid state and vice versa. Thus, using PCMs in structural engineering offers one of the best options for rapidly developing energysaving materials. To do so, ascaled model, concrete walls room, encapsulating locally available PCMs, was constructed in this study. Three locally available PCMs (glycerin, vegetable ghee, and ferric chloride hexahydrate) have been tested in a controlled environment. The model response is then evaluated for the energy-storing capacity of each PCM while considering the human comfort zone. From the test results, it is concluded that PCMs have a significant effect on improving the thermal energy efficiency of the model without any notable adverse effects. Over the completion of the test, after 12 hr, all the incorporated PCM showed positive results, and a maximum temperature loss of 2.25K was observed. Among different PCMs, the optimal performance was observed for vegetable ghee, which showed a drop in temperature for all the points at the inner side of the wall, i.e., T3, T4, and T5....
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