Journal of the Civil Engineering Forum

Numerical Study of Wave Reflection by The Curtain Wall-Pile Breakwater Using the SPH Model

2025-04-15T10:39:51+07:00

The Curtain Wall-Pile Breakwater (CPB) is comprised of a precast concrete wall structure that is upheld by pillars. The effectiveness of this breakwater has been extensively examined through experimental and numerical approaches in comparison to the conventional gravitational breakwater due to its reduced underwater footprint, which could be more environmentally sustainable. A Smoothed Particle Hydrodynamics (SPH) model using the open-source algorithm DualSPHysics is presented in this paper to simulate wave reflection on a CPB for multiple variables. This study focused on assessing the CPB’s performance in reflecting wave energy represented by the reflection coefficient (Cr), with a detailed investigation of two key parameters: relative depth, which is the ratio of wall depth to water depth (h/d) and wave steepness (Hi/L). The physical model was also tested in a laboratory flume to confirm the accuracy of the simulation results obtained through SPH. A fluid particle size of 0.5 cm was used, resulting in a simulation comprising approximately 9,320,717 particles. The results indicate that the Cr is directly proportional to the h/d and significantly influenced by Hi/L. Specifically, changes in h/d from 0.0 to 0.7 resulted in Cr increases from approximately 0.21 to 0.49 for lower wave steepness (Hi/L = 0.0097) and from approximately 0.36 to 0.60 for higher wave steepness (Hi/L = 0.0499). The quantitative analysis based on the quadratic regression equations shows that both the relative depth and wave steepness significantly influence the effectiveness of the CPB. The reflection coefficient increases with the relative depth, with a more significant effect observed for higher wave steepness. These findings underline the importance of considering both parameters in the design and optimization of breakwater structures to ensure robust and effective coastal protection.

The Effectiveness of Groin Modifications to Reduce the Impacts of Indian Ocean Dipole (IOD)-induced Port Siltation in Adapting to Climate Change

2025-04-15T10:39:50+07:00

Climate anomalies significantly affect coastal hydrodynamics, influencing sediment transport processes. The interaction between waves and currents plays an important role in sediment transport, which is closely related to climate anomalies, particularly the Indian Ocean Dipole (IOD). Indonesia is currently facing severe threats from port siltation due to the impacts of climate change. Port siltation results from sediment transport and can reduce the effectiveness and safety of port activities. This study aims to investigate sediment transport processes at Titan Coal Port under the influence of the IOD in 2016 and 2019. This port is located on the western coast of Sumatera, where high waves from the Indian Ocean pose a risk. Groins and a breakwater have been installed to protect the port from littoral drift induced by southeastern longshore currents and waves. However, the study found that during the negative IOD in 2016, hydrodynamic conditions led to shallowing of the port basin and navigation channel due to longshore currents from the northeast. The methods used in this research include descriptive analysis (using ERA-5 data from the Copernicus Climate Change Service) and numerical modeling (using MIKE 21) with bed level change identification at several points after groin modification scenarios. The combination of tidal currents and waves primarily shaped current patterns in the study area. High-speed currents caused significant erosion upstream at the bed level of the port basin. However, modified groin installations effectively reduced flow velocity entering the port basin. Two modified groin installation scenarios were tested in the study area to alter existing coastal hydrodynamics and sediment transport patterns.

Nonlinear Finite Analysis of Structural Behavior of Brick Masonry-Infilled Reinforced Concrete Frames

2025-04-15T10:39:50+07:00

Earthquake disasters are one source of disaster that often causes buildings to experience total collapse or partial damage so that the structure may no longer be usable. Brick masonry wall construction, both unreinforced and reinforced masonry walls, is starting to be widely used in the world. To study and interpret the behavior of brick walls under various loads, the numerical modeling approach offers a cheaper way to understand the structural response accurately compared to experimental approaches which require greater costs. Three-dimensional finite element analysis of masonry walls was performed using MSC. Marc/Mentat software to verify the analysis results with experimental results on brick masonry walls with concrete frame constraints. For brick walls, concrete frames are modeled with 3D solid elements, while reinforcing steel uses 3D truss elements. The strain stress is multi-linear for concrete and bi-linear for reinforcing steel. The modified Kent–Parker model was used to model the multi-linear stress-strain of the macro element of a brick wall. The Linear Mohr-Coulomb plasticity and the flow plasticity of the isotropic hardening rule were used for concrete and brick walls. Contact analysis was carried out between both concrete beams and concrete columns with walls. The loading was applied in the plane with the force control. The result of the analysis shows that the deformed shape of the brick wall is different from the experimental results because of the complexity of contact analysis and the macro element modeling of brick elements. The contact that occurs shows that there is no separation between the brick wall and the concrete frame. Based on the results of finite element analysis, the initial stiffness is the same between the finite element analysis result and the experimental result.

Identifying Prolonged Zero Value Periods as Part of Quality Control on Daily Rainfall Records in East Java, Indonesia

2025-04-15T10:39:50+07:00

Ensuring the quality of surface rainfall records is crucial for obtaining highly representative data and facilitating further comprehensive analysis. Given that surface rainfall observations are predominantly conducted using conventional gauges, they are still susceptible to human errors that can significantly impact data quality. Among various types of errors that may arise, the issue of zero rainfall records is relatively overlooked. Prolonged zero rainfall periods may introduce uncertainty, as mistyped missing data can be erroneously replaced with zero values. The challenge in handling this issue is complicated by the absence of sufficient evidence to conclusively determine the validity or suspicion of consecutive zero rainfall periods. Therefore, we implemented the Affinity Index, altitude difference, and maximum distance approaches to detect and evaluate (validate or reject) any potential invalid sequences of prolonged zero values in the rainfall dataset. The Affinity Index quantifies the agreement of rain and non-rain events between two meteorological stations, functioning as a metric to evaluate the similarity of their rainfall patterns. Utilizing daily data from 682 rain gauge stations in East Java, Indonesia, spanning from January 2010 to December 2019, we identified two major concerns: zero rainfall accumulation during the peak of the rainy season (December/January/February) and extended dry spells lasting more than 180 days. To address the first issue, we flagged the corresponding station and excluded it from the dataset. For the second issue, we established reference stations for each target station to enable meaningful comparisons. The study found that 8.8% of stations detected zero rainfall accumulation during the peak of the rainy season. Regarding prolonged dry spells, we successfully assessed 98% of extended dry spell events in East Java. The majority of these events were considered valid, while around 3% were deemed dubious.

Developing a Small-Scale Experimental Method for Evaluating the Effectiveness of Soil Improvement Using Prefabricated Vertical Drains

2025-05-09T13:15:14+07:00

Soft soils pose significant challenges in infrastructure development due to their low bearing capacity and high compressibility, which cause settlement and deformation over time through consolidation. Despite advancements in soil improvement techniques, faster and more efficient methods for accelerating soil consolidation remain crucial for achieving structural stability in a reasonable timeframe. Prefabricated Vertical Drains (PVD) have been widely adopted to accelerate soil consolidation, with their effectiveness typically evaluated through field-scale studies. However, field experiments can be time-consuming, costly, and influenced by site-specific variables, making controlled assessments challenging. We developed a small-scale laboratory experiment to evaluate the effect of PVD on soil consolidation. Soil samples were collected from the Padang-Pekanbaru Toll Road construction site in West Sumatra, Indonesia. Under controlled laboratory settings, two models were constructed—one with PVD and one without—using PVC pipes (20.32 cm diameter, 3.0 m height) filled with saturated soil to simulate field-scale soil columns. We found that PVD significantly enhanced soil consolidation. The rate of settlement on conditions without PVD was 1.2 times slower than that with PVD, particularly under lower loads. In contrast, PVD-enhanced models exhibit 5.3 times faster and greater settlement than conditions without PVD, along with 7.15 times higher water discharge. Metrics such as the coefficient of consolidation (Cv) and t90 values reinforced that PVD accelerated the consolidation process, particularly when subjected to higher loads. This study ultimately supports the development of more reliable laboratory methods for evaluating PVD applications, thereby enhancing design decisions across various consolidation scenarios and providing valuable insights for future infrastructure projects.

Exploring Hydraulic Behavior of Weir Using HEC-RAS at Semangir River Jember Regency

2025-05-09T13:15:14+07:00

Flooding significantly impacts communities living along riverbanks, causing severe damage to infrastructure and properties. The flood event on January 9, 2022, in Bumi Mangli Permai and Mangli Residence Housing, heavily damaged access roads. Effective flood control is essential to mitigate these risks, and one viable solution is the implementation of long storage systems, particularly motion weirs. This study explores the hydraulic behavior of the Semangir River in Jember Regency using the HEC-RAS program to model both fixed and motion weirs. Utilizing the SUH Nakayasu method, peak discharges for 25-year, 50-year, and 100-year return periods were estimated. The analysis revealed that the existing weir's design is inadequate for the 50-year return period. However, simulations indicate that a motion weir with gate dimensions of 1.5 m x 1.75 m offers improved hydraulic conditions, reducing water surface elevation and flow velocity compared to both the existing and initially planned weirs. These findings support the adoption of motion weirs as an effective flood control strategy for the Semangir River.

Relationship between occurrence of lahar and hydraulic properties of ashfall covered ground in the Arimura River basin of Sakurajima Volcano, Japan

2025-05-09T13:09:28+07:00

When volcanic ash accumulates on the surface layer of slopes, it decreases the hydraulic conductivity of the ground, which can trigger lahars even due to small rainfall. Understanding the impact of changes in surface conditions on lahar occurrence is crucial for disaster prevention. This study employed a runoff analysis model based on the kinematic wave method to evaluate the surface conditions indirectly by hydraulic conductivity parameter values at the time of lahar occurrence. This study tried to reveal the relationship between the change of hydraulic conductivity parameter values in each lahar event and observed monthly ashfall data. The study area is the Arimura River basin in Sakurajima, Japan. Sakurajima volcano is still active today (2025), and new fresh volcanic ash is depositing on the surface ground. As a result, the model can find the optimal parameter in 41 out of 55 lahar events that occurred in the Arimura River basin on Sakurajima between 2015 and 2020. Next, we examined the characteristics of lahar events that could not be reproduced by our runoff analysis model. As a result, we found that lahars which occur after a lot of volcanic ashfall or contain large boulders have bad reproducibility. Next, we analyzed the relationship between the optimal parameter values for the 41 events and the monthly observed ashfall data. The results indicated a trend in which the optimal parameters decrease under conditions of increasing monthly ashfall, and the coefficient of determination was approximately 0.18. When considering the effect of preceding rainfall prior to lahar, a visual tendency was observed for the hydraulic conductivity parameter values to decrease with increasing preceding rainfall.

Advancing Road Safety in Urban Area: The Impact of Roundabouts on Intersection Design

2025-05-09T14:39:36+07:00

Intersection represents a significant challenge around road traffic safety, posing a major problem, particularly during peak hour of urban road traffic. The high risk of accidents at this congested intersection is a serious concern, given that they involve a variety of road users, including vehicles and pedestrians. To address these challenges and minimize the risks related to intersections, roundabout have emerged as a significant effort. To address these challenges and minimize risks related to intersections, roundabouts have emerged as a notable solution. This approach does not only contribute to improved traffic flow but also enhances overall road safety by providing a more efficient alternative compared to conventional intersection designs. This study takes a comprehensive look at the safety performance of roundabouts as an alternative intersection design, by systematically reviewing relevant literature from Scopus and Google Scholar, aiming to explain how roundabout intersections contribute to crash reduction and traffic safety improvement. The analysis reveals that roundabouts generally lead to a significant reduction in severe collisions and enhance traffic flow efficiency. This is primarily due to their design, which minimizes conflict points and promotes lower vehicle speeds, and positively impacts the visibility and safety of pedestrian crossings. However, the roundabout has challenges, such as the requirement for drivers to adapt to new traffic patterns and the public's perception of the different aspects of the roundabout design. The findings indicate that roundabouts substantially improve road safety, evidenced by significant reductions in fatal and injury crashes. The literature also emphasizes the importance of customizing roundabout design and implementation to specific conditions, highlighting that such adapting is critical to maximizing benefits and ensuring positive impacts on road safety which is important to developed in further research.