Journal of the Civil Engineering Forum

Cold-Formed Steel Truss Roof Structure Failure Considering Seismic Load and Buckling Analysis

Muslikh, Miftahul Iman — Fri, 29 Aug 2025 17:06:19 +0700

There were many incidents of cold-formed steel roof truss structures in the last 5 years in Indonesia. Various kinds of allegations have been addressed to cold-formed steel material applications especially in the case of seismic resistance. Some of them concern the authenticity of the steel material itself and the selection of cold formed steel material. On the other hand, recently, people have installed (assembled) cold-formed steel trusses without involving a certified cold-formed steel applicator. This research is based on a numerical study that modeled the collapse pattern of cold-formed steel truss roof structures by considering buckling failure and the seismic load capacity. The cold-formed steel roof truss structure was modeled with 3D-truss elements in two model types: the overall structure and a single compression member element in 3D solid idealization. Buckling analysis with eigenvalue and nonlinear static analysis was performed to evaluate the critical load (Pcr). The buckling mode shape also was also compared with the mode shape of modal analysis. This research also evaluated the effect of seismic load on the overall cold-formed steel truss structure and the slenderness of the compression member. The numerical simulation of cyclic loading on the single compression member was conducted in this research. The numerical analysis results showed that cold-formed steel roof truss structure have high vulnerability to seismic hazard effect. The cold-formed steel material has lower ductility than hot rolled steel material. This causes the lateral displacement that occurs to be lower than the displacement produced by the hysteretic curve of numerical cyclic simulation. This research also evaluated the dynamic properties, such as frequency, periods, and mode shapes, of some typical cold-formed steel for roof truss structure.

Evaluating the Role of Mechanical Connections and Reinforcements in Modular Timber Beam Behaviour

Mohd Rizuwan Mamat, Mohd Hisbany Mohd Hashim, Noorsuhada Md Nor — Tue, 16 Sep 2025 00:00:00 +0700

Modular timber construction faces critical challenges in connection performance, with mechanical joints representing the weakest structural elements in segmented systems, particularly for rapid-deployment infrastructure applications such as temporary forest bridges. This research addresses the fundamental knowledge gap regarding the combined effects of mechanical connections and reinforcement strategies on modular timber beam structural behavior. The study investigates modular timber beam flexural performance through experimental evaluation of steel U-shaped connectors and Chopped Strand Mat (CSM) reinforcement applied to the tension zones, examining how beam segmentation affects structural integrity. Ten I-section modular timber beams with lattice-web configuration underwent three-point bending tests using a Shimadzu AG-IS 100 kN Universal Testing Machine at 6.6 mm/min loading rate, with specimens spanning 3.0 meters supported at 2.7-meter intervals. Test specimens featured varying segmentation patterns (0.6m, 0.75m, 1.0m, and 1.5m segment lengths) connected via U-shaped steel connectors and bolts, with selected beams receiving 5mm thick CSM reinforcement at the bottom flanges. Mechanical properties including modulus of elasticity (MOE), modulus of rupture (MOR), and flexural stiffness were systematically measured to quantify reinforcement and segmentation effects on joint behavior and structural continuity. Results demonstrate that CSM reinforcement provides substantial performance improvements, with ETR136 achieving a 49% increase in ultimate load capacity (29,397 N vs 19,709 N for ETN131) and superior ductility characteristics. However, segmentation introduces significant structural vulnerabilities, with five-segment beams (ETN50.65) showing a 49.5% capacity reduction compared to continuous specimens. The research reveals that while CSM reinforcement effectively delays crack initiation and reduces peak tensile strain by an average of 31%, mechanical joints remain critical failure points due to stress concentrations at the timber-bolt interfaces. The three-segment configuration emerges as optimal for balancing structural performance with practical modularity requirements. These findings provide essential design guidance for modular timber systems in rapid-deployment applications, emphasizing the need for optimized connection strategies and hybrid reinforcement techniques to enhance the structural integrity and durability of segmented timber infrastructure.

Enhancing Soil Liquefaction Prediction: Overcoming Data Challenges in SPT-Based Machine Learning with Imputation Technique

Fandi Fadliansyah, Fikri Faris, Wahyu Wilopo, Ardiansyah — Thu, 13 Nov 2025 08:13:00 +0700

In addition to the adverse effects of earthquakes, the loss of soil-bearing capacity during liquefaction can exacerbate damage to buildings. Liquefaction phenomena involve many parameters, making it more complex to evaluate. Machine learning has been studied to deal with liquefaction complexity in recent decades. However, incomplete liquefaction data can result in missing information, complicating model development across various datasets. Therefore, this study aims to assess the capability of machine learning models to predict liquefaction by implementing the missing value imputation technique. Seismicity, soil properties, and soil condition parameters were utilized to develop models. Random Forest (RF), k-Nearest Neighbor (k-NN), and eXtreme Gradient Boosting (XGBoost) were trained by applying feature selection and parameter optimization based on standard penetration test (SPT) data. The confusion matrix was used to assess the performance of the model based on the performance matrix of Overall Accuracy (OA), Precision (Prec), Recall (Rec), F1-Score (F1), and Area Under the Curve (AUC). In addition, the preprocessing stage included data normalization and outlier treatment to enhance the reliability of model predictions, ensuring consistent learning behavior across different variable scales. The results show that the RF achieved the highest performance (OA = 90.71%), which is comparable to findings from other previous studies. The AUC results indicate that the models deliver excellent classification performance. These findings suggest that the integration of imputation and preprocessing techniques can significantly improve data-driven approaches in geotechnical earthquake engineering. In conclusion, the missing imputation is quite effective in the predictive model. Finally, this study offers a new perspective on developing machine learning models using a more user-friendly software and applying imputation techniques to handle missing data.

Sustainable Concrete Using Ground Granulated Blast Furnace Slag and Polypropylene Fibers: Flexural Behavior of RC Beams

Thu, 13 Nov 2025 08:31:50 +0700

As sustainability becomes a central focus in the construction industry, the combined use of supplementary cementitious materials and discrete fiber reinforcement offers an innovative pathway to enhance both environmental and structural performance. This study investigates the mechano-microstructural interaction between a dense Ground Granulated Blast Furnace Slag (GGBFS)–based matrix and polypropylene (PP) fibers in reinforced concrete (RC) beams, emphasizing the performance trade-offs among key mechanical properties. The experimental program comprised two phases. First, GGBFS replacement levels of 30% and 45% (by binder mass) were evaluated for compressive strength to identify the optimal matrix. Second, PP fibers were incorporated at 0, 3, 5, and 7 kg/m³ into the selected matrix. Tests under standardized curing conditions measured compressive strength, flexural load capacity, ductility, toughness, and stiffness. Microstructural analysis assessed fiber–matrix bonding quality and crack-bridging mechanisms. The 30% GGBFS mixture achieved the highest compressive strength in the optimization phase. Fiber inclusion produced distinct performance trade-offs: 3 kg/m³ delivered the best combination of strength and toughness, 5 kg/m³ maximized ductility, and 7 kg/m³ yielded the highest initial stiffness but slightly reduced post-peak energy absorption. These findings demonstrate that no single fiber dosage is universally optimal; instead, the choice should be based on prioritizing specific performance criteria. Microstructural observations revealed dense interfacial transition zones and effective fiber anchorage in GGBFS-rich matrices, enhancing crack control and delaying propagation. This study’s primary contribution lies in establishing a clear link between microstructural features and quantified mechanical trade-offs, providing a framework for performance-based mix design. The identified trade-offs also offer direct guidance for performance-based design, enabling engineers to tailor mix compositions to targeted applications such as seismic resilience, deflection-sensitive spans, or impact-resistant members.

Seismic Fragility of Fixed and Flexible Base RC Bridge under Near-Fault Directivity Effects

Wed, 19 Nov 2025 14:05:19 +0700

Reinforced Concrete bridges are widely used in highway infrastructure due to their cost-effectiveness and structural redundancy. However, they are highly vulnerable to seismic hazards, particularly in near-fault regions where ground motions exhibit extreme intensity and short-duration energy pulses. Near-fault ground motions are characterized by high-energy velocity pulses with long periods, pulse-like waveforms, and significant peak values, which can lead to severe structural damage. As modern design practices shift toward performance-based design, the vulnerability of bridges under these different types of near-fault ground motions have become an emerging area of interest for researchers and designers. However, a common practice is to assume fixed-base conditions for bridge piers during vulnerability assessments, which may lead to inaccurate results. The effect of assuming fixed-base conditions on the vulnerability assessment of bridge piers remains an open question. This study presents a comprehensive comparative analysis of seismic damage propagation in a simply supported multi-span RC bridge subjected to near-fault pulse-like ground motions with directivity effects. The bridge is modeled under two distinct foundation conditions: fixed-base and flexible-base, with the latter incorporating soil-structure interaction through a pile group foundation. The analytical framework employs Incremental Dynamic Analysis to develop seismic fragility curves, offering a thorough evaluation of the system-level performance. The results reveal that SSI significantly alters the structural response, with median normalized changes of approximately 27% in drift and 30% in base shear. In some cases, the normalized drift demand increased by up to 76.8%, whereas the normalized base shear decreased by up to 51.1%, indicating substantial shifts in deformation and force distribution. These variations significantly affect the energy dissipation capacity of the bridge, which is essential for mitigating damage progression and enhancing seismic resilience.

Experimental Study on Compressive Strength, Flexural Strength, and Microstructure of Epoxy Mortar as Concrete Repair Mortar

Bonaventura Haryanto Umbu Tay, I Nyoman Sutarja, Ida Bagus Rai Widiarsa — Wed, 19 Nov 2025 14:34:40 +0700

his study investigates the potential of custom-formulated epoxy-based concrete repair mortar as an alternative material for structural applications. Conventional commercial mortars, while practical, often exhibit limitations in long-term strength and durability. This research evaluates the mechanical and microstructural performance of epoxy mortar using a self-mixed composition consisting of epoxy resin, cornice adhesive, and silica sand. Three variations were developed based on the ratio of epoxy resin to cornice adhesive (50%, 70%, and 100%), and were labeled as RE0.5, RE0.7, and RE1. A commercial epoxy–cement-based mortar, Sikafloor-81 Epocem (SF), was used as a benchmark for comparison. Specimens were prepared in the form of cubes and prisms and tested at curing ages of 7, 14, and 28 days for compressive and flexural strength. Microstructural characteristics were analyzed using X-ray fluorescence (XRF), X-ray diffraction (XRD), and scanning electron microscopy (SEM). At 28 days, the compressive strength values were 30.88 MPa for RE0.5, 48.56 MPa for RE0.7, 51.84 MPa for RE1, and 18.00 MPa for SF. Flexural strength results at 28 days reached 25.74 MPa (RE0.5), 31.18 MPa (RE0.7), 32.54 MPa (RE1), and 8.32 MPa (SF). Elemental analysis confirmed that the high silica content in the fine aggregate and the presence of calcium sulfate in the filler contributed to a denser and more rigid matrix. Crystalline phase analysis revealed quartz as the dominant structure, and microstructural observations indicated fewer pores and cracks in RE1 and RE0.7 compared to SF. These results indicate that a carefully optimized epoxy mortar formulation can exceed the performance of commercial products such as SF, offering enhanced mechanical strength and improved microstructural integrity for use in concrete repair.

Hydrated Lime–Based Coating for Cool Pavement Technologies: Evaluation of Durability and Thermal Performance

Muhammad Khuzamy, Taqia Rahman, Imtiaz Ahmed, Syed Bilal Ahmed Zaidi — Tue, 25 Nov 2025 14:30:16 +0700

Heat-reflective pavement coatings are commonly employed for road cooling and to mitigate Urban Heat Island (UHI) effects by reflecting solar radiation and reducing surface temperatures. However, their cooling efficiency diminishes over time due to abrasion, soiling, UV exposure, and environmental aging, which degrade the reflective polymer layer. As a cost-effective alternative, hot-rolled hydrated lime (HL) applied to pavement surfaces has emerged, forming a light-coloured mineral layer that enhances reflectivity and potentially reduces pavement temperature. This study investigates hydrated lime (HL) as a mineral-based alternative, applied through hot-rolling to form a reflective surface layer that is compatible with conventional asphalt practices. Its performance was evaluated through laboratory thermal simulations (day–night cycling) and abrasion wear testing and compared with three commercial paint-based HRCs: epoxy resin–TiO₂ and acrylic emulsion–TiO₂. The results show that HL coatings achieved surface temperature reductions of up to 21.89 °C compared to uncoated asphalt, exceeding the best-performing paint-based sample (White-AE, 19.29 °C), suggesting that HL has strong potential as an effective reflective coating. This was achieved with a formulation of fine HL particles (No. 400 mesh) at a higher dosage (200 g/m²). In abrasion resistance tests, HL outperformed paint based HRCs, with lower mass losses (0.6–1.3 g vs. 0.8–1.5 g), which was attributed to stronger adhesion and particle embedment. In addition, post-abrasion tests revealed that HL samples retained better thermal stability, with smaller temperature increases (ΔT: 5.9–6.8 °C) than HRCs (ΔT: 6.3–7.2 °C). Based on these outcomes, HL applied at 200 g/m² using fine particles (No.400 mesh) is recommended as the optimal formulation for maximizing cooling performance and surface durability. Overall, these findings suggest that hot-rolled HL is a durable, low-cost, and effective alternative cooling strategy to popular HRCs for UHI mitigation.

The Effect of Pyrolysis Temperature on the Performance of Sewage Sludge Biochar for Persulfate-based Oxidation of Bisphenol-A

Nurul Alvia Istiqomah, Thi Vinh Nguyen, Dick Dick Maulana — Thu, 27 Nov 2025 15:03:24 +0700

Converting sewage sludge into biochar shows promise as an eco-friendly and cost-effective method for remediating pollutants. In this study, aerobic digested sewage sludge was evaluated as a low-cost carbon-based catalyst through a facile one-pot pyrolysis process. The sludge biochar (SBC) was then used as a persulfate (PS) activator for the degradation of Bisphenol-A (BPA). The effect of pyrolysis temperature on the physicochemical properties of SBC and catalytic activity was observed. Then, chemical quenching analysis was carried out to identify reactive species. Increasing the pyrolysis temperature from 350 to 700 °C resulted in an enhancement of the degradation rate constant of BPA from 0.95 × 10^-2 min^-1 to 8.9 × 10^-2 min^-1. SBC pyrolyzed at 350 °C (A350), characterized by a high iron content (40%wt) in the form of amorphous Fe (e.g., ferrihydrite) and C=C functional group promoting the radical formation which is dominated by presence of hydroxyl radicals. However, iron in an amorphous form limited the catalytic activity of A350. By contrast, non-radical pathway dominates SBC pyrolyzed at 700 °C (A700) with highest BPA removal as the result of more hydrophobic nature (lower O/C) therefore attracting more BPA and PS to the biochar surface. Graphitic structure of A700 (lower I_D/I_G) supports the mediated electron transfer pathway for persulfate activation. A pH range of 2–9 and the of inorganic anions (e.g., Cl^-,NO₃^-,SO₄^-, and HCO₃^-) had negligible effects on the A700 system. This study introduces a novel approach to the value-added reuse of sewage sludge as an efficient persulfate activator for pollutant remediation with good resistance to water matrices conditions.