Marlia Adriana, Norminawati Dewi, Budi Kurniawan
et al.
Penelitian ini bertujuan untuk menganalisis korelasi antara nilai berat jenis dan kuat tekan pada batu bata konvensional serta batu bata dengan campuran abu kayu akasia dan abu las karbit sebagai bahan aditif ramah lingkungan. Metode penelitian dilakukan melalui tahapan persiapan bahan tanah liat, pencampuran dengan komposisi 85% tanah dan 15% bahan aditif pada variasi kadar air 20 ml, 25 ml, dan 35 ml, kemudian dilakukan pencetakan, pengeringan selama 7 dan 14 hari, serta pengujian berat jenis dan kuat tekan. Hasil penelitian menunjukkan bahwa penambahan abu akasia memberikan pengaruh paling signifikan terhadap peningkatan berat jenis dan kuat tekan batu bata dibandingkan dengan abu las karbit maupun batu bata konvensional. Nilai berat jenis tertinggi sebesar 5,967 g/cm³ dan kuat tekan maksimum sebesar 12,603 MPa diperoleh pada sampel batu bata dengan campuran abu akasia pada umur 14 hari. Korelasi positif antara berat jenis dan kuat tekan menunjukkan bahwa peningkatan densitas berkontribusi terhadap peningkatan kekuatan mekanik batu bata. Penelitian ini membuktikan potensi pemanfaatan limbah abu akasia sebagai bahan pengisi yang dapat memperkuat struktur batu bata tanpa proses pembakaran.
Explosions, including those from war weapons, terrorist attacks, etc., can lead to damage and overall collapse of bridges. However, there are no clear guidelines for anti-blast design and protective measures for bridges under blast loading in current bridge design specifications. With advancements in intelligent construction, precast segmental bridge piers have become a major trend in social development. There is a lack of full understanding of the anti-blast performance of precast segmental bridge piers. To study the engineering calculation method for blast load acting on a typical precast segmental reinforced concrete (RC) pier in near-field explosions, an air explosion test of the precast segmental RC pier is firstly carried out, then a fluid–structure coupling numerical model of the precast segmental RC pier is established and the interaction between the explosion shock wave and the precast segmental RC pier is discussed. A numerical simulation of the precast segmental RC pier in a near-field explosion is conducted based on a reliable numerical model, and the distribution of the blast load acting on the precast segmental RC pier in the near-field explosion is analyzed. The results show that the reflected overpressure on the pier and the incident overpressure in the free field are reliable. The simulation results are basically consistent with the experimental results (with a relative error of less than 8%), and the fluid–structure coupling model is reasonable and reliable. The explosion shock wave has effects of reflection and circulation on the precast segmental RC pier. In the near-field explosion, the back and side blast loads acting on the precast segmental RC bridge pier can be ignored in the blast-resistant design. The front blast loads can be simplified and equalized, and a blast-resistant design load coefficient (1, 0.2, 0.03, 0.02, and 0.01) and a calculation formula of maximum equivalent overpressure peak value (applicable scaled distance [0.175 m/kg<sup>1/3</sup>, 0.378 m/kg<sup>1/3</sup>]) are proposed, which can be used as a reference for the blast-resistant design of precast segmental RC piers.
Michel Corci Batista, Ivana Kelly Cintra Reinisz, Taisy Fernandes Vieira
et al.
This article presents an innovative interdisciplinary approach to teaching the solar system in lower secondary education (9th grade), grounded in David Ausubel’s Meaningful Learning Theory and the STEAM (Science, Technology, Engineering, Arts, and Mathematics) methodology. Traditional astronomy teaching often fails to connect with students’ prior knowledge, resulting in superficial and fragmented learning. Addressing this issue is crucial for fostering deeper cognitive engagement and preparing students for complex, interdisciplinary challenges. However, there is a notable gap in the literature regarding integrating Ausubel’s theory with the STEAM approach, particularly in astronomy education at the lower secondary level. The study, conducted with 9th-grade students, employed active learning strategies such as planetarium visits, hands-on model construction, mind mapping, and collaborative projects to foster a holistic understanding of astronomical concepts. The proposal aimed to bridge prior knowledge with new content by integrating these methods, promoting critical thinking and creativity. Results demonstrated significant improvements in students’ ability to articulate and apply astronomical knowledge, highlighting the effectiveness of combining theoretical frameworks with experiential and interdisciplinary activities. The study underscores the potential of such approaches to address challenges in astronomy education, preparing students for contemporary cognitive demands while cultivating a deeper appreciation for the cosmos.
Steel–ultra-high-performance concrete (UHPC) composite beams with small-rib-height perfobond strip connectors (SRHPBLs) exhibited advantages of light weight and high bearing capacity, demonstrating the potential for applications of UHPC in bridge engineering. During service stages, the composite beams were usually under combined tension–shear loads, rather than pure shear loads. Nevertheless, there were research gaps in the static behavior of SRHPBLs embedded in UHPC under combined tension–shear loads, which limited their applications in practice. To address this issue, systematic experimental and theoretical analyses were conducted in the present study, considering the test variables of tension–shear ratio, row number, and strip number. It was demonstrated that the tension–shear ratio had less effect on ultimate shear strength, initial shear stiffness, and ultimate slip of SRHPBLs. When the tension–shear ratio was increased from 0 to 0.42, the shear capacity, initial shear stiffness, and slip at peak load of SRHPBLs decreased by 24.31%,19.02%, and 22.00%, respectively. However, increasing the row number and strip number significantly improved the shear performance of SRHPBLs. Compared to the single-row specimens, the shear capacity and initial shear stiffness of the three-row specimens increased by an average of 92.82% and 48.77%, respectively. The shear capacity and initial shear stiffness of the twin-strip specimens increased by an average of 103.84% and 87.80%, respectively, compared to the single-strip specimens. Finally, more accurate models were proposed to predict the shear–tension relationship and ultimate shear capacity of SRHPBLs embedded in UHPC under combined tension–shear loads.
To address the engineering challenges associated with Guilin red clay, such as its potentially low strength and unfavorable mechanical behavior, this study investigated the effectiveness of lignin and lime as modifiers. Consolidation undrained triaxial tests and scanning electron microscopy (SEM) were employed to evaluate the strength characteristics and microstructural changes in modified clay specimens with varying dosages. The results demonstrate distinct strengthening mechanisms: Lignin exhibits an optimal dosage (6%), significantly increasing cohesion and internal friction angle through physical reinforcement (“soil fiber” formation), but higher dosages (8%) lead to particle separation and strength reduction. In contrast, lime provides continuous and substantial strength enhancement with increasing dosage (up to 8%), primarily through chemical reactions producing cementitious compounds (e.g., C-S-H, C-A-H) that densify the structure. Consequently, lime-modified clay shows significantly higher cohesion and internal friction angle compared to lignin-modified clay at equivalent or higher dosages, with corresponding stress–strain curves shifting from enhanced (strain-hardening) to softening behavior. These findings provide practical insights into red clay improvement in geotechnical engineering applications.
Surfactants are extensively used in chemical flooding due to their excellent ability to reduce oil-water interfacial tension， alter rock surface wettability， and promote oil-water emulsification. It was previously believed that the middle phase microemulsion could only occur at high surfactant concentrations. Therefore， the evaluation of surfactants for chemical flooding mostly depends on interfacial tension measurement. The role of microemulsion phase behavior technology in the screening and development of surfactants for tertiary oil recovery is neglected. Thanks to the technological advancement in surfactant development in the past two decades， ideal middle phase microemulsions have been achieved by crude oil systems with low acid values at low surfactant concentrations. As a result， it is imperative to use microemulsion phase behavior technology to guide the development of new surfactants and the performance optimization of the composite system. This paper started with the concept and classification of microemulsions and systematically introduced four emulsification types of microemulsions， namely Winsor Ⅰ， Ⅱ， Ⅲ， and Ⅳ. The formation mechanism of the four types of microemulsions was described from the aspects of oil-water interfacial tension， surfactant molecular structure， and micellar morphology. The mechanism involved instantaneous negative interfacial tension theory， duplex film theory， R ratio theory， and geometric arrangement theory. The microemulsion phase behavior technology was introduced in detail in terms of phase pattern identification， composition calculation of oil， water， and surfactant in the microemulsion phase， and laboratory operation. In terms of processing results of phase behavior experiments， it was introduced in detail how to calculate the solubilization index of the oil and water phases in the microemulsion through their respective volume changes and how to calculate the interfacial tension between the microemulsion phase and oil and water through the solubilization index， so as to determine the optimal salinity of the composite system. This paper hopes to attract people’s attention to the microemulsion phase behavior technology and promote its application in the research and development of surfactants for high-efficiency tertiary oil recovery， the study of oil displacement mechanism， and the optimization of composite system formulation， thus improving the technical level of compound flooding in China.
Chemical technology, Petroleum refining. Petroleum products
Sediment flux of many rivers has been significantly reduced due to human activities caused by economic development, leading to increasingly severe riverbed degradation. To prevent riverbed degradation, grade control structures (GCSs) have been widely applied in degrading channels. Existing studies have not provided a good understanding of the effects of GCSs on flow characteristics and bed morphology in degrading channels, limiting the management of degrading channels. A series of flume tests with no sediment supply are conducted to investigate the effects of GCSs on upstream water levels and riverbed morphology in degrading channels. The experimental results indicate that: (1) in the initial stage of degradation, the water surface slope in the backwater reach is linearly and negatively correlated with the GCS-height Froude number, based on the average flow velocity upstream of the backwater reach due to GCS and the height of GCS; (2) the effective protection bed length upstream of GCS is approximately equal to the length of the reach where the flow velocity is less than the critical velocity for sediment motion in the backwater zone; (3) for sequential GCSs, the effective protection bed length will decrease if GCS is located in the backwater reach of the downstream GCS. A semi-analytical calculation method of the effective protection length and equilibrium bed profile upstream of GCS in degrading channels is proposed based on the critical condition of sediment motion and weir flow formulas. The computed values by the proposed calculation method agree well with the experimental data of the present study.
River protective works. Regulation. Flood control, Harbors and coast protective works. Coastal engineering. Lighthouses
It is our pleasure to publish the October issue (4th issue) of Vol. 2 of the International Journal of Bridge engineering, Management and Research. You can find detailed information about the journal in the inaugural issue of the journal in September 2004 or at www.ijbemr.org. In this issue of the journal, we are pleased to bring to you the following six papers in innovative areas of bridge engineering: Clustering-Based Framework for Multi-Sensor Data Fusion in Bridge Deck Condition Assessment Influence of Nose Position of Edge Fairing on Aerodynamic Characteristics of Box Girder Bridge Deck Seismic Isolation in Newly Built Bridges in Italy: Historical Development, Regulations, and Recent Applications Smart Acoustic Sounding for Automated Delamination Detection in Concrete Bridge Decks Dynamic investigations before and after the strengthening of a masonry arch bridge History of Bridges: Materials and Structural Types of a Monument to Progress
For continuous steel–concrete composite girder bridges based on the post-combined method, the conventional rectangular group studs contribute to the isolation of the steel girder and the concrete slab before prestressing, leading to the majority of prestress forces being introduced to the concrete slab. However, rectangular-group stud holes cause the prestress forces to be unevenly distributed. In this study, a new type of bellow-sleeved stud (BSS) was developed to mitigate the weakening effects of rectangular group stud holes on the slab. A steel corrugated sleeve with a diameter of 60 mm was employed to cover the stud, which served as an internal formwork to prevent the concrete from bonding with the root of the stud. After prestressing was complete, the steel sleeve was filled with ultra-high-performance concrete (UHPC) to create a reliable combination between the concrete slab and the steel girder. To investigate the shear performance of this new type of connection, eight push-out test specimens were designed, and finite-element models were built. This study drew a comparison between the BSS and the ordinary headed stud (OHS). The research findings suggested that the BSS is subjected to less bending–shear coupling and offers a 4.5% increase in shear strength and a 31.9% increase in shear stiffness compared with the OHS. The study also analyzed the structural parameters influencing the shear performance of the BSS. It is found that the steel sleeve of the BSS has a negative effect on shear performance, but this can be mitigated by infusing high-strength material into the sleeve. Furthermore, the study examined the effect of construction quality on shear performance and suggested that sleeve deviation and grout leakage considerably reduced the shear performance of the BSS. Accordingly, strict control over the construction quality of the BSS is necessary.
Increasingly, research indicates that steel fibers can significantly enhance the engineering properties of mortar and concrete; however, few studies have examined their impact on the reinforcement of in-service tunnel linings within sleeve arch structures. In this study, a series of 1:2 scale experiments were conducted using a specialized loading device to compare the reinforcement performance of steel fiber-reinforced concrete sleeve arches and traditional reinforced concrete sleeve arches on prefabricated cracks with depths of 1/3 and 2/3 of the lining thickness. The experimental results were validated using numerical simulations. The results indicate that under the same load, when reinforcing components with 2/3 prefabricated cracks, the maximum compressive strains for steel fiber-reinforced and reinforced concrete sleeve arches were −852 με and −985 με, respectively, and the maximum deflections were 3.57 mm and 5.48 mm. Composite sleeve arches of both materials provide a certain degree of reinforcement to linings with varying damage. The reinforcement performance of steel fiber-reinforced concrete sleeve arches is superior to that of traditional reinforced concrete sleeve arches, with particularly significant reinforcement for linings with 2/3 prefabricated cracks. Numerical simulations have shown that the stress in reinforced concrete at the concentrated stress regions is 16.15%, 6.01%, 12.68%, 36.62%, and 4.82% higher than that in steel fiber-reinforced concrete, respectively, thereby validating the reliability of the experimental results. Therefore, this study recommends the application of steel fiber materials in sleeve arches to achieve superior maintenance and reinforcement, addressing cracking issues in in-service tunnel linings and thereby improving the safety and durability of these structures.
The dynamic response characteristics of high and steep slopes under the action of earthquakes and blasting was focused on, especially the frequency distribution and propagation laws, which are crucial for slope stability assessment. Using stress wave theory as the theoretical basis and advanced FLAC3D numerical simulation technology, we systematically analyze the frequency response of slope under different joint conditions under seismic waves. The nonlinear characteristics of reflected P-wave coefficient and the significant sensitivity of joint to incident wave frequency are revealed when the Angle of incident P-wave changes. The results show that with the increase of the incidence Angle of the incident P-wave, the reflection coefficient of the reflected P-wave decreases slowly at first and then increases sharply to 1.0. The reflection coefficient of the wave at the joint is more sensitive to the frequency of the incident wave. In a biplanar rock mass, multiple reflections of waves between structural planes produce transmitted waves with different time differences.
The aging degree of reclaimed asphalt pavement (RAP) is complex and diverse, and the current utilization rate of RAP is far from meeting the needs of green cycle development. To explore the effect of Styreneic Methyl Copolymer (SMC) rejuvenator of aging asphalt and the performance of SMC regenerated asphalt mixture containing 50% and 60% RAP, this study used SMC rejuvenator to regenerate SBS-modified asphalt with different aging degrees. The high and low-temperature rheological properties of regenerated asphalt were evaluated by temperature sweep test, multi stress creep recovery test, and bending beam rheometer test. Then, the recommended content of the SMC rejuvenator was obtained by using Matlab to establish the corresponding model. Finally, the road performance of the regenerated mixture with high-content RAP was verified. The test results showed that the recommended content range of the SMC rejuvenator for the aging asphalt with PAV (Pressurized Aging Vessel) 0 h, PAV5h, PAV10h, PAV15h, PAV20h were 1.56∼2.31%, 3.03∼3.36%, 4.269∼4.48%, 5.23∼5.66%, 5.95∼6.91%, respectively. The road performance of the SMC regenerated asphalt mixture with 50% and 60% RAP content met the specification requirements. SMC rejuvenator had no significant negative impact on high-temperature performance, significantly improving low-temperature cracking resistance. SMC regenerator had a positive significance in improving regeneration efficiency.
Materials of engineering and construction. Mechanics of materials
Animesh K Gain, Mohammed Mofizur Rahman, Md Shibly Sadik
et al.
The Ganges-Brahmaputra (GB) delta is one of the most disaster-prone areas in the world due to a combination of high population density and exposure to tropical cyclones, floods, salinity intrusion and other hazards. Due to the complexity of natural deltaic processes and human influence on these processes, structural solutions like embankments are inadequate on their own for effective hazard mitigation. This article examines nature-based solutions (NbSs) as a complementary or alternative approach to managing hazards in the GB delta. We investigate the potential of NbS as a complementary and sustainable method for mitigating the impacts of coastal disaster risks, mainly cyclones and flooding. Using the emerging framework of NbS principles, we evaluate three existing approaches: tidal river management, mangrove afforestation, and oyster reef cultivation, all of which are actively being used to help reduce the impacts of coastal hazards. We also identify major challenges (socioeconomic, biophysical, governance and policy) that need to be overcome to allow broader application of the existing approaches by incorporating the NbS principles. In addition to addressing GB delta-specific challenges, our findings provide more widely applicable insights into the challenges of implementing NbS in deltaic environments globally.
Abstract The objective of this paper is to investigate the seismic responses of long-span and asymmetrical suspension bridges subjected to four intensity level (Small, moderate, huge, and super earthquakes) of near-fault ground motions. A typical suspension bridge located in Yunnan province of China is selected herein to study the dynamic response of long-span and asymmetrical suspension bridges. And the corresponding finite element model based on the platform of OpenSEES is established to consider the influence of velocity pulse effect, site effect, and structure-soil interaction on the seismic responses of interests e.g., tower, girder, and pile, etc., in the suspension bridge seismic analysis. Besides the near-field and far-field ground motion records are employed from the data base in Pacific Earthquake Engineering Research Center of the United States for comparison analysis. Finally numerical analysis results have suggested that the influence of near-fault effect on the response of long-span and asymmetrical suspension bridges and the different dissipation capacity of nonlinear viscous damper in various intensity levels should be paid more attention to in the seismic design of this type bridges.
Innovations in Cyber-Physical System (CPS) are driven by functionalities and features. Mechanical Engineering, on the other hand, is mainly concerned with the physical product architecture, i.e., the hierarchical arrangement of physical components and assemblies that forms the product, which is not explicitly linked to these functions. A holistic model-driven engineering approach for CPS, therefore, needs to bridge the gap between functions and the physical product architecture to enable agile development driven by automation. In the theoretical field of mechanical design methodology, functional architectures describe the functionality of the system under development as a hierarchical structure. However, in practice, these are typically not considered let alone modeled. Existing approaches utilizing mechanical functional architectures, however, do not formalize the relation between the functional architecture and the geometric design. Therefore, we conceived a meta-model that defines modeling-languages for modeling functional architectures of mechanical systems and physical solutions, i.e., interconnections of physical effects and geometries, as refinements of the functional components. We have encoded the meta-model as a SysML profile and applied it within an interdisciplinary, industrial project to model an automotive coolant pump. Our contribution signposts the potential of functional structures to not only bridge the gap between function and geometry in mechanics but also to integrate the heterogeneous domains participating in CPS engineering.
Abstract Floods, bridge scour, and flood-associated loads have caused over sixty percent of bridge failures in the U.S. Current practices for the vulnerability assessment of instream bridges under the effect of such flood largely rely on qualitative methods, such as visual inspection, without considering uncertainties associated with structural behaviors and flood loads. Recently, numerical methods have been investigated to quantitatively consider such uncertainty effects by adapting fragility analysis concept that has been well established in the earthquake engineering area. However, river hydraulics, geotechnical uncertainties of foundation, variable scour-depth effects, and their significance in structural fragility of bridges have rarely been systematically investigated. This study proposes a comprehensive fragility analysis framework that can effectively incorporate both flow hydraulics and geotechnical uncertainties, in addition to commonly considered components in flood-fragility analysis of bridges. The significance of flow hydraulics and geotechnical uncertainties has been demonstrated through a real-bridge case study. Conventional fragility curves with maximum scour depth may not represent actual vulnerability during floods, as the scour may not reach to the maximum in many cases. Therefore, fragility surface with two intensity measures, i.e. flow discharges and scour depths, is introduced for real-time vulnerability assessment during floods in this study.
In this paper, factors affecting the mechanical properties of polymeric granite artificial stone have been investigated. Epoxy resin and three types of additives called Poly ether ether ketone, Silicon rubber, and Nanoclay have been used to make the artificial stone. Unlike previous research on resin alone, this study has been conducted on artificial stone and samples made using these materials. These samples are compared with the control sample and the sample with optimal mechanical characteristics. The method of making artificial stone is that crushed stone blend with resin, and is molded into molds that are defined according to the American Association of Materials and Testing. Samples were made with two percentages of 7.5 and 15 percent to determine the optimum amount of additive. After curing, the sample is subjected to testing. The results obtained from these experiments for artificial stone show that the addition of polyether ether ketone to epoxy resin compressive strength by more than 30%. 7.5wt% of Nanoclay increases more than 6% in compressive strength in epoxy resin. Therefore, the amount of 7.5% by weight of the additive has been selected as the optimum percentage and only this percent is considered in the manufacture of flexural and tensile strength samples. Adding Silicon rubber to the epoxy resin, increases the flexural strength by 7%. Contrary to expectation, Nanoclay reduces flexural strength significantly. By examining the results of the tensile test, it was determined that the addition of silicon to the epoxy resin increased the resistance to 46% . It is concluded that the addition of silicon rubber has been effective in increasing the compressive strength and in increasing the flexural and tensile strength and adding polyether ether ketone.
During earthquakes, extended pile-shaft–supported bridges in laterally spreading ground can undergo inelastic deformations, especially in their embedded portions. Following earthquakes, it is critical to assess damage to these difficult-to-inspect portions and determine whether vehicles can safely pass bridges. This paper aims to identify optimal aboveground engineering demand parameters (EDPs) that are readily measurable after earthquakes and have high-quality probabilistic associations with post-earthquake load-carrying capacity of bridges as well as underground difficult-to-inspect EDPs. For this purpose, an experimentally validated bridge-soil-foundation model considering liquefaction-induced lateral spreading is adopted and subjected to ground-motion time histories in the transverse direction. Subsequently, pushdown analyses are performed to assess the post-earthquake vertical load-carrying capacity of bridges. Metrics such as efficiency, practicality, and measurability are established and examined for EDPs. Results show that residual column drift ratio is the optimal EDP for load-carrying capacity assessments, whereas maximum column drift ratio best predicts pile demands. Furthermore, developed probabilistic relationships between residual and maximum column drift ratios will assist in preliminary post-earthquake evaluation of bridges for damage assessment and posting decisions.
A novel probabilistic approach for model updating based on approximate Bayesian computation with subset simulation (ABC-SubSim) is proposed for damage assessment of structures using modal data. The ABC-SubSim is a likelihood-free Bayesian approach in which the explicit expression of likelihood function is avoided and the posterior samples of model parameters are obtained using the technique of subset simulation. The novel contributions of this paper are on three fronts: one is the introduction of some new stopping criteria to find an appropriate tolerance level for the metric used in the ABC-SubSim; the second one is the employment of a hybrid optimization scheme to find finer optimal values for the model parameters; and the last one is the adoption of an iterative approach to determine the optimal weighting factors related to the residuals of modal frequency and mode shape in the metric. The effectiveness of this approach is demonstrated using three illustrative examples.