Journal of Civil Engineering and Materials Application
Volume:7 Issue: 2, Spring 2023

The prevalence of various types of experimental and numerical uses in this area is mostly due to the significance of welded connections in the behaviour of steel moment-resisting frames (SMRFs). The most effective conditions that aggravates the undesirable performance of welded connections is high-temperatures. With regard to conduct analytical research, three types of welded angle seat connections will be selected for finite element modeling (FEM) in ABAQUS software to investigate the performance of them under high-temperature loading. The parameters of increasing thickness, length of welded angle seat connection, and simple connection with angle by adding stiffener are assessed. For this aim, a flexible angle seat connection is used to help the web angle. The characteristics of the web angles and seats are determined based on the features of the beam. Based on the results, the sample COL-ST10-L50-SP15 has the best performance versus other samples. In this sample, beam to column connection is welded angle seat with dimensions such as 10 mm thickness, 50 mm length and 15 mm thickness of stiffener. The displacement of this sample is 502.52 mm under heat conditions. It means that the displacement ratio of the mentioned sample is 18.25% versus reference sample. Therefore, the results showed that by increasing the heat, two important factors should be suggested in the design of steel connections. These factors such as increasing the force due to longitudinal expansion and decreasing the strength and stiffness are considered.

Gridshell structures have the potential to develop the construction process of free-form structures, offering numerous benefits. These include the minimum use of materials, light-weighting, the creation of a large span structure, structural efficiency, organic shapes, potential for quick and cost-effective construction, column-free spaces, maximum transparency, sustainability, and ease of deconstruction and recycling. Gridshells, regarding their architectural potential and intrinsic geometric rationality, are well-suited for creating complex shapes. Hence, the properties of gridshells depend on the equivalent pre-stress of the two-dimensional grid that was deformed. The mechanical properties of glass fiber reinforced polymer (GFRP), such as high elastic limit strain, strength, and Young’s modulus, can further enhance the potential of gridshell structures. Gridshell structures offer numerous opportunities for constructing double curvature shells. However, they also present challenges, particularly in the design and construction process, while minimizing stress and preventing breakages of elements under the influence of forces. This paper presents a review of GFRP elastic gridshell structures, including design and construction methods. Additionally, a case study of an existing gridshell structure, the Solidays gridshell, is presented. Finally, the opportunities and challenges associated with gridshell structures are discussed.

Three trial embankments as TS1, TS2, and TS3 that were built for the investigation of a soil treatment project in Bangkok were modeled and verified based on the reported data. To clarify the importance of integration of the hydraulic modifier function vs stress, in the verified models, the modifier functions were omitted and the FEM models were run in the absence of the function. It was shown that after the omission of the hydraulic modifier, the results were overestimated especially for the TS1 and TS2, which had smaller PVDs (prefabricated vertical drains) distance. For the TS1 embankment, the settlement increased from 0.78 m to 0.87 m in 210 days. In 365 days, the settlement increased from 1.27 m to 1.44 m. For the TS2 embankment, the settlement increased from 0.93 m to 1.67 m in 230 days. In 410 days, the settlement increased from 1.36 m to 2.27 m. For the TS3 embankment, the settlement increased from 1.15 m to 1.79 m in 230 days. In 410 days, the settlement increased from 1.52 m to 2.24 m. The inclusion of the hydraulic function that calibrates the model for every step of loading is essential in the modelling such problems. For the design phase, this function should be calculated from lab tests, preferably undisturbed samples that were bored from the site, and the resultant function be used as an inseparable part of modeling and calculations.

The face of concreting has been revolutionized with the development of self-compacting concrete, the introduction of Microbial Induced Calcite Precipitation (MICP) in concrete as well as the use of secondary cementitious materials in concrete, as it helps to improve the pore characterization of the concrete by the filling of the pore spaces and hence enhance its porosity and durability. The use of these revolutionary concrete however requires the optimization of the constituents and/or additives to concrete in order to maximize the properties thereof. There is thus a need to arrive at optimal materials quantities that can maximize the porosity characterization of the concrete without recourse to many trial and error experimentations that are both time and resources consuming. The application of modelling tools in concrete technology aids in the optimization of concrete constituents for optimal self-compacting concrete performance. In this research linear optimization models for predicting the water absorption and sorptivity of the Bio- self-compacting concrete incorporating sporosarina Pasteurii at different bacterial cell density and nutrient content with respect to age of concrete were developed for these concrete properties at 7 and 28 days with the bacterial concentration and calcium calcite content as the independent variables and water absorption and sorptivity as dependent variables; and the developed models validated using experimental data in DataFit Software. Results obtained showed that the developed linear models which took the quadratic form y(x)=a_1+a_2 x+a_3 x^2+⋯+a_n x^(n-1) were adequate for the prediction and optimization of the water absorption and sorptivity of the bio- self-compacting concrete.

Coastal High-Performance Concrete (HPC) structures face deterioration challenges from exposure to biodegradables like algae and moss. This study examined the durability of coastal HPC under these biodegradable influences, emphasizing their effects on various transport properties. Conducted over 2 years in the environmentally rigorous Bandar Anzali Ports, the research evaluated key HPC transport properties such as water absorption, Rapid Chloride Penetration Test (RCPT), Rapid Chloride Migration Test (RCMT), electrical resistivity, and freeze-thaw resistance. Experimental samples, replicating real-world coastal conditions, incorporated diverse algae and moss concentrations.The comprehensive testing indicated that algae and moss presence notably hastened HPC degradation. Samples exposed to these organisms demonstrated increased water absorption, evidenced by weight gain. Enhanced chloride penetration and migration were evident from RCPT and RCMT results, suggesting an elevated corrosion risk in the concrete structures. Moreover, a marked drop in electrical resistivity indicated reduced concrete capacity to impede electrical current, while freeze-thaw tests showed heightened damage vulnerability from cyclic freezing and thawing.In light of these findings, it's crucial to address the biodegradable impact on coastal HPC structures. Implementing strategies like routine cleaning and maintenance to reduce algae and moss, combined with appropriate surface treatments, can extend the lifespan of coastal concrete installations. These insights aid in creating resilient and sustainable concrete mixes specific to coastal applications, ensuring extended structure longevity and integrity.Keywords: Coastal structures, High-Performance Concrete (HPC), algae, moss, durability