Ari Wibowo

This study evaluates the effectiveness of friction dampers in improving the seismic performance of non-structural components in hospital buildings. A five-story reinforced concrete hospital, intentionally modeled to exceed allowable drift limits, was analyzed using nonlinear time history analysis under three earthquake scenarios: BSE-1E (225-year), BSE-2E (975-year), and BSE-2N (2475-year), assuming soft soil conditions. Non-structural components were classified as drift- or acceleration-sensitive, with damage probabilities assessed using fragility curves and categorized into risk classes. Results show that friction dampers significantly reduced damage probability for acceleration-sensitive components up to 74% for cabinet contents under BSE-1E. However, drift-sensitive elements remained vulnerable, particularly in higher-intensity events, due to the building's flexible design and limited damper activation. While friction dampers improved global structural performance, their effectiveness declined with increasing seismic demand. These findings underscore the potential and limitations of friction dampers in retrofitting hospital buildings and highlight the need for careful damper sizing and consideration of alternative strategies to protect non-structural systems.

The seismic evaluation of existing bank office buildings is critical for ensuring post-earthquake operational continuity. This study investigates a 14-story RC bank building in Kendari using the Nonlinear Static Procedure (NSP) per ASCE 41-17, targeting an Immediate Occupancy (IO) performance level. The initial analysis revealed a critical contradiction: while the structure's global performance appeared to meet the IO target, this assessment was found to be misleading. A detailed, element-based analysis identified a concealed local failure where a critical beam reached the Life Safety (LS) performance level, caused by a non-trivial Positive Moment at the support. A sequential Fiber Reinforced Polymer (FRP) retrofitting strategy was then implemented. The primary contribution of this study is the demonstration of the Failure Migration phenomenon. It was shown that a naive, 'single-point' retrofit (on LS-1) did not solve the problem but merely shifted the failure mode to the next weakest element (LS-2). This sequential retrofitting procedure proved necessary to track the migrating failure, which moved non-linearly between various floors, until all migrating vulnerabilities were eliminated. This finding proves that a sequential procedure is necessary to address Force Redistribution and achieve a true IO performance. The final minor global base shear increase (0.16%) was only a secondary benefit, confirming the objective was local vulnerability elimination, not a significant increase in global stiffness.

This paper discusses the effect of acidic environments on concrete structures, particularly crack width. This study was conducted to investigate the effect of acid ph on crack width in reinforced concrete beams with different cover depths. Reinforced concrete beams were immersed in phosphoric acid (H3PO4) solution with a pH of 5.0 for 28 days using this technique. Three concrete cover thicknesses were tested: 20 mm, 30 mm, and 40 mm. The materials used include coarse aggregate, fine aggregate, cement and phosphoric acid solution. Crack width, concrete compressive strength and steel stress were measured while the two-span beams with different section shapes experiencing point loads. The findings demonstrated that exposure of concrete to an acidic environment led to a decrease in compressive strength between 15% and 40%, cracking becoming significant with the beams having thin layers, while these results range a crack width ranging from no visible cracks until cracks resulted opened up. Crack width is directly dependent upon the thickness of concrete, for thicker concrete layer reducing crack width. On the other hand, steel stress increases crack width, with more the steel stress greater is crack wider. This study is unique in that an empirical formula related to crack width can be used for the prediction and has a good agreement with experimental results. The results yield new understanding on the significance of controlling concrete cover depth and steel stress level in the design methodologies for reinforced-concrete structures to be more acid-resisting. These findings may have implications for the design of reinforced concrete structures that are more resistant to acidic environmental conditions

This research focuses on the impact resistance of reinforced concrete enhanced with bamboo fibers, aiming to evaluate the influence of varying bamboo fiber content on impact energy, deflection, and impact force. Reinforced concrete beams were prepared with bamboo fiber contents of 1.25%, 2.5%, and 3.75%, representing a range of low to high volume fractions. The primary objective was to examine how bamboo fiber addition improves the concrete’s mechanical performance under repeated impact loads and to determine the optimal fiber dosage for structural efficiency. The results indicate that the incorporation of bamboo fibers significantly reduces both maximum deflection and peak impact force. Notably, the 1.25% fiber content exhibited the highest increase in the Toughness Modulus (MoT), reflecting superior energy absorption capacity. Conversely, higher fiber contents (2.5% and 3.75%) led to a noticeable decline in MoT values, likely due to poor fiber dispersion and agglomeration effects. Graphical analysis of polynomial regression curves revealed that although bamboo fiber generally enhances energy absorption, each energy parameter exhibits a different trend. Released energy shows a moderately increasing trend with higher fiber content, but with high variability at elevated percentages, indicating inconsistency. Absorbed energy displays minor and inconsistent fluctuations across all fiber contents, suggesting limited fiber influence. In contrast, deformation energy peaked at 1.25% fiber content and declined sharply beyond 2.5%, implying that excessive fiber reduces the material’s deformation ability. These findings confirm that bamboo fibers are a viable, sustainable additive to improve the impact resistance of concrete

The pH level plays a crucial role in the properties of concrete, including compressive strength, durability, and resistance to corrosion of reinforcement. The influence of pH still requires in-depth investigation to determine its effect on concrete strength under varying pH levels and immersion durations in seawater. The compressive strength test was carried out on a total of 540 concrete samples. The test specimens used in this study were cylindrical in shape, with a height of 30 cm and a diameter of 15 cm. The target compressive strengths in this research were 25 MPa, 35 MPa, and 45 MPa. The selected pH values were 5, 7, 9, and 11. Concrete specimens were immersed in pH-adjusted solutions od seawater for 7, 14, and 28 days, with daily monitoring of the pH levels. The aim of this study was to determine the effect of hydrogen potential pH on concrete. The test results confirmed that pH variation during immersion in seawater had a significant impact on the compressive strength of concrete. The effect of both acidic and alkaline hydrogen potential pH on the compressive strength fc' at different immersion durations indicated that the 7-day immersion period had the greatest impact in reducing concrete strength. The predictive equations for the relationship between pH and compressive strength are fc' = 5.85x + 0.55 (acidic pH) and fc' = -2.67x + 63.50 (alkaline pH).

The presence of bamboo fiber has been distributed to improve the structural integrity of construction. It has been used to resist impact loads and reduce crack widths in composite materials. This can be utilized for reinforcement in construction, particularly in mortar elements. Bamboo fiber has been used to resist impact loads and reduce crack widths in composite materials. This can be utilized for reinforcement in construction, particularly in mortar elements. By combining good treatment with alkaline NaOH, the quality of the fiber used as a mortar mix will increase and the capacity to absorb impact energy will be greater. In this study there were 2 stages, the first stage was to look at the effect of the effective length of bamboo fiber and alkaline molarity. The effect of treatment using alkaline is to reduce the lignin and hemicellulose substances which reduce the bond in the mortar mixture. The optimal value for the Pull-out test, which involved manipulating the molarity of NaOH as a treatment and the effective length of bamboo fiber, was determined to be 2.5 cm of embedded fiber or a total length of 5 cm when 4 molar NaOH was utilized. All fiber bamboo-composite bars had a cross section of average at 1×1 mm. And the second stage tested Charpy for impact load resistance in mortar with the optimum effective fiber length while varying the alkaline molarity. The objective of the Charpy impact test was to determine the optimal quantity of bamboo fiber to be incorporated into mortar when subjected to impact loads. standard Charpy impact test specimen is 55×10×10 mm in dimension. Experimental data show that the effective length and treatment of bamboo fiber affected the bond strength with mortar. A proportional relationship was observed between the addition of fiber to the mortar and an increase in compressive strength; The research findings indicate that the lowest modulus of toughness is 0.329 MPa, or equivalent compressive strength at 15.583 MPa, while employing 3.25 % bamboo fiber in mortar with a fiber length of 5 cm and a 12 % alkaline treatment

The rapid progress of development in the Surabaya area, especially in areas crossed by the Waru segmentation fault, Wiyung District, and Lakarsantri, is marked by the number of residential developments and tall buildings which will certainly contribute to the value of natural disaster vulnerability, earthquakes. So, to reduce the risk value of loss to casualties and material losses from potential earthquakes, further mitigation is needed. The aim of this study is to determine the dominant factors for building vulnerability and earthquake natural disaster mitigation in the Waru segmentation fault area. One of the analytical methods used is the Importance Index (IMPI) method, this analysis method is carried out to determine the most dominant risk level from existing risks and bowtie analysis is used to manage, reduce and mitigate the most dominant risks. Based on the results of research and risk assessment, the most dominant risk level variable for building vulnerability due to Waru segmentation faults is variable 2 c (finishing with heavy loads such as concrete or precast panels that are not firmly attached to the structure) with an IMPI value of 83.13 %. The presence of finishing with heavy loads such as concrete or precast panels that are not firmly attached to the structure in the event of an earthquake disaster in the Waru Fault will endanger and can bring down people around the building. To reduce the risk of casualties due to earthquakes in the Waru Fault, it is necessary to prevent by providing an additional number of dynabol bolts, enlarging the reinforcement at the façade and canopy joints, locking concrete cavities with special concrete stucco additives and conducting surveillance monitoring during construction

Cracks in concrete structures due to tensile weakness can be repaired by using fiber concrete, including medical mask waste as an additive in high-strength concrete mixes. This research the influence of polypropylene fiber from medical mask waste on the mechanical characteristics, flexural behavior, and crack width of high-strength reinforced concrete (RC) beams. The initial stage involved examining the properties of the concrete constituent materials. The testing process was based on a high-strength concrete mix design using the Aitchin method mix design sheet. Compressive strength and split tensile strength were tested at fiber content (0 %, 0.15 %, 0.20 %, and 0.25 %). The three-point flexural testing procedure was carried out at 28 days on 1200×100×150 (mm) RC beams. The use of LVDT, strain gauge, and other measuring devices supported the acquisition of the required data. The results showed that the split tensile strength reached the optimum value of 66.19 MPa at 0.24 % fiber content. Polypropylene fiber from medical mask waste in RC beams showed a positive impact on reducing crack width at increased split tensile strength. Waste mask fiber content of 0.15 %, 0.20 % and 0.25 % gave stable and better results compared to 0 % content (no fiber). With high steel stress (fs), and high strain, it offers the potential to improve the mechanical properties of high-strength concrete, thereby reducing the width of cracks that occur. This improves the tensile weakness of the concrete. The effect of split tensile strength on the crack width (w) of beams with the formula approach: wexp=3.74ftf-1.513, wan=0.187ftf-0.022 shows that the experimental results have a significant effect on decreasing the crack width that occurs in high-strength RC beams, thereby improving the quality of concrete Тріщини в бетонних конструкціях через слабкість на розтяг можна усунути за допомогою фібробетону, в тому числі відходів медичної маски як добавки до високоміцних бетонних сумішей. Це дослідження впливу поліпропіленового волокна з відходів медичної маски на механічні характеристики, поведінку при вигині та ширину тріщини балок із високоміцного залізобетону (ЗБ). На початковому етапі досліджували властивості бетонних складових матеріалів. Процес випробування базувався на проектуванні високоміцної бетонної суміші з використанням таблиці розрахунку суміші за методом Айтчина. Міцність на стиск і міцність на розрив випробовували при вмісті волокон (0 %, 0,15 %, 0,20 % і 0,25 %). Процедуру триточкового випробування на згин проводили через 28 днів на RC балках 1200×100×150 (мм). Використання лінійного змінного диференціального перетворювача, тензодатчиків та інших вимірювальних пристроїв підтримало отримання необхідних даних. Результати показали, що міцність на розрив досягла оптимального значення 66,19 МПа при вмісті волокна 0,24 %. Поліпропіленове волокно з відходів медичної маски в ЗБ балках продемонструвало позитивний вплив на зменшення ширини тріщини при збільшенні міцності на розрив. Вміст клітковини у відпрацьованій масці 0,15 %, 0,20 % і 0,25 % дав стабільні та кращі результати порівняно з 0 % вмістом (без клітковини). Завдяки високому напруженню сталі (fs) і високій деформації він пропонує потенціал для покращення механічних властивостей високоміцного бетону, тим самим зменшуючи ширину тріщин, які виникають. Це покращує міцність бетону на розрив. Вплив межі міцності на розрив на ширину тріщини (w) балок із підходом формули: wexp=3,74ftf-1,513, wan=0,187ftf-0,022 показує, що експериментальні результати мають значний вплив на зменшення ширини тріщини, яка виникає в високоміцні ЖБ балки, тим самим покращуючи якість бетону

The Strong and safe Building is designed to avoid structural failure from an earthquake or the other causes. Internet of Things (IoT) based real-time wireless s The Strong and safe Building is designed to avoid structural failure from an earthquake or the other causes. Internet of Things (IoT) based real-time wireless s