Advances in Civil Engineering

Nowadays, building structures in corrosive environments requires some considerations. Being lightweight, high tensile strength, and corrosion resistance are the features that make fiber-reinforced plastic (FRP) bars an alternative component for longitudinal steel reinforcement of concrete. On the other hand, the linear elastic behavior of FRP bars, alongside the brittle behavior of concrete, makes brittle members without considerable ductility. In this paper, the effect of compression region confinement with CFRP sheets on the FRP-reinforced concrete beams was experimentally investigated. Eight GFRP reinforced beams with 2 m length, including one reference beam and seven confined beams, were constructed and tested under a four-point bending test. Based on the type of confinement, specimens are categorized into four groups. Flexural behavior improvements, including load carry capacity, energy dissipation capacity, and ductility, were observed in at least one specimen of each confined group. According to the results, the specimen that was spirally confined with a 30 mm ribbon width and angle of 10° had the best total energy absorption up to about 110% improvement in comparison to the unconfined specimen. On the other hand, vertically confined specimens with 50 mm ribbon width showed the highest improvement in ductility indices and load carrying capacity up to 60% and 11% in comparison to unconfined specimens, respectively. Due to concrete compression zone fractures in flexural failure mode, the over-reinforce method is considered the design philosophy. Results indicate that regardless of the confinement type (discrete vertical, discrete spiral, or continuous spiral confinement), there is an optimal amount for width, blank space between ribbons, and depth of confinement to achieve the best flexural behavior.

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.

Primarily generated at the interface between the wheel and the rail, railroad vibrations then propagate through the supporting soil. If these vibrations reach nearby bridges and buildings, they amplify the vibration nuisance and cause ground noise, which has detrimental effects on nearby residents, sensitive equipment, and historic structures. By analyzing measured data from metro vibration field vibration experiments, this article attempts to contribute to the body of knowledge on environmental vibration propagation patterns by offering insightful conclusions. Before analyzing the deformation response of the metro jet system (MJS) vibration isolation piles to the structure and the ground, we investigated the effect of MJS vibration isolation piles in the ground of the existing subway tunnel structure on the control of vibration of the proximate structure and conducted dynamic tests on the vibration of bridges without vibration isolation measures caused by operating subway trains. The tests determined that the acceleration of the bridge’s lateral vibration exceeded the code limit; one of the contributing factors was that the bridge’s structure had already sustained damage. The utilization of MJS isolation piles was also discovered to safeguard the extant bridge pile foundations. The paper presents an innovation in the form of economically viable vibration mitigation strategies that were implemented subsequent to the identification that the lateral vibration acceleration of the preexisting bridge surpassed the prescribed code standards. Considerable insight is gained regarding the design and implementation of vibration control systems for structures situated near caverns, encompassing deep foundation works.

Loess has unique water sensitivity due to its distinct formation environment. The structure of loess is undercompactness, weak cementation, and porousness. The water sensitivity of loess directly leads to many environmental problems and geological hazards, including subgrade subsidences, slope collapse or failures, and building cracking. To reveal the relationship between water sensitivity and loess structure, confined-compression collapsibility tests and triaxial-collapsibility tests were performed on loess in different areas. The collapsibility coefficient, porosity ratio, and collapsibility rate were analyzed. Results show that the collapsibility process of loess can be divided into three stages: wetting, softening, and settling. The collapsibility sensitivity of loess is determined primarily by its structural and hydraulic state.

The aim of this study is to investigate the engineering properties and solidification mechanism of loess through the use of alkali-activated coal gangue powder with sodium silicate. Experimental methods and comprehensive analysis were employed to examine the effects of different proportions of alkali-activated coal gangue powder with sodium silicate on the engineering properties of loess, including mass shrinkage, compressibility, and shear strength. Additionally, scanning electron microscopy was utilized to gain in-depth insights into the interaction and solidification mechanism between loess and alkali-activated coal gangue powder. The results show that the sodium silicate alkali-activated gangue powder curing loess has significantly improved the compressive strength and shear strength of the loess. With a ratio of 7 : 2 : 1, the 28 days compressive strength of solidified loess is 1.7 MPa, and the shear strength is 67.92 kPa, which is 1.91 and 2.13 times the 28 days compressive strength and shear strength of unmixed gangue powder and sodium silicate specimens respectively. The hydration–hydrolysis reaction, ion-exchange reaction, and volcanic ash reaction of the gangue powder under an alkaline environment generated hydrides that filled the pores between soil particles, enhanced the interparticle cohesion, and made the internal structure of the specimens denser, improving the engineering performance of loess solidification. The proposed sodium silicate alkali-activated gangue powder curing loess mechanism can provide a theoretical reference for the engineering application of gangue powder and the curing modification of loess.

Sedimentation in the harbors’ basins is an environmental phenomenon that frequently disrupts safe shipping and necessitates costly dredging operations. The layout of harbors and the permeability of protective structures such as breakwaters influence sediment transport within harbor basins. Thus, through a multistep framework, this study investigates the sedimentation management issues for the Egyptian proposed Ezbet Elborg fishing harbor based on field measurements and a numerical morphodynamic coastal modeling system (CMS). First, field measurements were analyzed and evaluated for acquiring a full grasp of the research area’s bathymetry and hydrodynamics. Second, a two-dimensional (2D) numerical simulation CMS model was set up and calibrated against field measurements wherein the developed CMS model highly correlated with actual measurements by 97%. CMS results demonstrate that the predominant NNW wave with the formed longshore current on both the harbor’s sides affects sediment accumulation within the harbor’s basin. Third, 100 simulations for the proposed harbor including different structural modulation scenarios affecting the sedimentation issue were investigated via the calibrated CMS model. Finally, an exploratory data analysis (EDA) is performed via correlation matrix and ANOVA test for the CMS’s scenarios’ results to gain an in-depth view of the relation between the harbors’ layout and the structural characteristics with the sedimentation volumes. Results showed that breakwaters’ orientation affects sediment accumulation more than its length. Also, breakwater permeability and basin width are significantly affecting sediment accumulation. Ultimately, the current study makes a substantial contribution to integrated coastal structure management (ICSM) by helping coastal stakeholders to mitigate the negative impacts of the harbors’ sediment deposition aiming at sustaining both environmental and economic aspects.