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International Symposium of the International Federation for Structural Concrete, fib Symposium 2023

作者： Çalım, Furkan Soydan, Cihan Güllü, Ahmet Yüksel, Ercan Faculty of Civil Engineering Istanbul Technical University Istanbul Turkey Department of Civil Engineering Tekirdag Namik Kemal University Tekirdag Turkey Ingram School of Engineering Texas State University San MarcosTX78666 United States

ISBN: (纸本)9783031325182

The structures in the seismic regions are designed to dissipate energy through inelastic behavior under strong ground motions based on the conventional seismic design practice, which makes them vulnerable to damage during major earthquakes releasing large amounts of seismic energy. On the other hand, replaceable energy dissipative devices are used as fuse members to diminish the energy demands of the structural elements and guarantee a reliable earthquake-resistant design. In this paper, a numerical investigation was performed for the performance improvement of an RC frame using a novel lead extrusion damper (LED). A one-bay and one-story bare reinforced concrete specimen, which has previously been tested under the effect of variable-amplitude displacement cycles based on the "ACI 374.2R – Guide for Testing Reinforced Concrete Structural Elements under Slowly Applied Simulated Seismic Loads", was employed. Once the generated numerical model was validated through the experimental data, a new model in which the frame is equipped with the LED was evaluated under the same procedure. In addition, the effect of different configurations for the damper installation on the overall performance of the RC frame was discussed. Based on the analysis results, it can be stated that the LED significantly improved the seismic performance of the RC frame in terms of the amount of dissipated energy and damping ratio. Moreover, the hysteretic energy of the beam and column elements was reduced by the installation of the LED to the frame. It is also noteworthy that the RC frame’s behavior was considerably affected by the damper installation configuration. © 2023, The Author(s), under exclusive license to Springer Nature Switzerland AG.

关键词： Energy dissipation

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Constitutive Model Characterization of the RC Columns Using Energy Terms 2nd

Constitutive Model Characterization of the RC Columns Using ...

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2nd International Workshop on Energy-Based Seismic engineering, IWEBSE 2023

作者： Güngör, Bilal Hasanoğlu, Serkan Çalım, Furkan Muderrisoglu, Ziya Dindar, Ahmet Anıl Bozer, Ali Özkaynak, Hasan Güllü, Ahmet Department of Civil Engineering Gebze Technical University Kocaeli Turkey University School for Advanced Studies IUSS Pavia Italy Faculty of Civil Engineering Istanbul Technical University Istanbul Turkey Department of Civil Engineering Beykent University Istanbul Turkey Department of Civil Engineering Eskişehir Technical University Eskişehir Turkey Ingram School of Engineering Texas State University Texas United States

ISBN: (纸本)9783031365614

The accuracy level of predicting the hysteretic response of structural members is crucial in energy-based design procedures. Probabilistic methodologies are generally implemented to consider the uncertainties related to demand and capacity-based parameters in structural analyses. Accordingly, implementing the large variability on critical parameters that affect the accuracy level of predicted response is still a challenging issue. This proceeding focuses on an improved calibration methodology proposed to select the optimal analytical modeling parameters that takes into account the widely-used modeling techniques. The input data used for the calibration procedure is compiled from quasi-static experiments conducted on reinforced concrete column members exist in the literature. The finite element models of 62 test units are established to predict the energy dissipation characteristics by utilizing a set of modeling assumptions. Here, the optimal ranges of critical analytical model parameters are evaluated to increase the accuracy level in predicting the target energy dissipation capacity of a member. A comparison between the predicted responses for default and the calibrated model parameters is revealed. Results provide a basis for an efficient calibration methodology to get more accurate capacity predictions. Since the predictions for the damage level of structural members is directly related to the accuracy level of an established analytical model, this attempt is expected to have a considerable impact on the energy-based design of structural members. © 2023, The Author(s), under exclusive license to Springer Nature Switzerland AG.

关键词： Energy dissipation

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Enhancing Public Engagement in Sustainable Systems through Augmented Reality 41

Enhancing Public Engagement in Sustainable Systems through A...

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41st International Symposium on Automation and Robotics in Construction, ISARC 2024

作者： Lee, Yu-Chen Alsuhaibani, Abdullah Cheng, Chih-Shen Leite, Fernanda Sustainable Systems Program Maseeh Dept. of Civil Architectural and Environmental Engineering The University of Texas at Austin AustinTX United States Civil Engineering and Project Management Program Maseeh Dept. of Civil Architectural and Environmental Engineering The University of Texas at Austin AustinTX United States Civil Engineering and Project Management Program Maseeh Dept. of Civil Architectural and Environmental Engineering The University of Texas at Austin AustinTX United States Dean for Research Cockrell School of Engineering Joe J. King Professor in the Maseeh Dept. of Civil Architectural and Environmental Engineering The University of Texas at Austin AustinTX United States

ISBN: (纸本)9780645832211

The sustainability of building infrastructure has been a growing critical global concern. However, stakeholders often overlook the sustainability aspect of systems in their everyday lives. This paper presents an exploration of the potential of augmented reality (AR) technology as a tool for enhancing public engagement around sustainable systems in buildings. We introduce an innovative approach to address the challenge of gap between sustainable infrastructure and user awareness. Through data collection such as access counts, usage duration, and user feedback, we can evaluate the effectiveness of AR applications in improving awareness and engagement in sustainability. This study illustrates how AR technology can facilitate a deeper connection between the public and sustainable systems, thus paving the way for a more environmentally friendly society. © 2024 ISARC. All Rights Reserved.

关键词： Sustainable development

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DEVELOPMENT OF A LOW THERMAL EXPANSION NANOCOMPOSITE RESIN FOR MSLA 3D PRINTER

DEVELOPMENT OF A LOW THERMAL EXPANSION NANOCOMPOSITE RESIN F...

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SAMPE 2024 Conference and Exhibition

作者： Sufian, Muhammad A. Sheley, Rahul R. Shadman, Wasi Tanim, Ibrahim K. Cooper, Benicia Tate, Jitendra Materials Science Engineering and Commercialization Program Texas State University 601 University Drive San MarcosTX78666 United States Ingram School of Engineering Texas State University San MarcosTX78666 United States

ISBN: (纸本)9781934551455

Masked Stereolithography (MSLA) is a 3D printing technique that uses an LCD screen and a UV LED light source operated digitally to selectively cure photosensitive resin, forming a three-dimensional object through successive layers cured upon one another. Using MSLA offers superior dimensional precision, efficient surface finish, and printing resolution limits of 30 µm to 140µm, allowing to obtain complex 3D geometries. Using this technique gives advantage of astonishing results in the resolution of 3d printer surface but many times lacks in obtaining desired material properties compared to other available techniques. To overcome this lacuna one of the methods is to create a thin layer coating of nickel plating over the resin which enhances the mechanical strengths, heat diffraction, and resistance to chemicals. In this scenario, the CTE of resin does not align with that of nickel metal. This results in internal stresses when exposed to the harsh environment of space causing the part failure. In this work, an attempt has been made by using epoxy as a base resin and introducing nanomaterial Multi-Walled Carbon Nanotubes (MWCNTs) to reduce the CTE. Out of all different loading levels of MWCNT 0.5 wt% loading showed maximum reduction in terms of CTE which is more than 25% compared to neat resin. Tensile strength and tensile modulus increased by more than 47% and 61%. While flexural modulus increased by 66% and percentage elongation showed a reduction by 38% compared to neat resin. © 2024 Soc. for the Advancement of Material and Process engineering. All rights reserved.

关键词： Nickel plating

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FATIGUE AND FATIGUE DAMAGE MECHANISMS OF HIGH-TEMPERATURE THERMOPLASTICS COMPOSITES: A REVIEW 10

FATIGUE AND FATIGUE DAMAGE MECHANISMS OF HIGH-TEMPERATURE TH...

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10th Composites and Advanced Materials Expo, CAMX 2024

作者： Sheley, Rahul Tate, Jitendra Tehrani, Mehran Materials Science Engineering and Commercialization Program United States Ingram School of Engineering Texas State University 601 University Drive San MarcosTX78666 United States Jacobs School of Engineering University of California 9500 Gilman DriveLa Jolla San DiegoCA92093 United States

ISBN: (纸本)9781934551462

The growing demand for materials that can withstand extreme conditions in the aerospace and automotive industries has led to significant research on high-temperature polymeric composites. These composites are designed to maintain their structural integrity and mechanical properties at temperatures above 300 degrees Celsius. The development of these advanced materials is crucial for improving the performance and safety of aerospace and automotive components operating in extreme environments. Traditionally, thermosets were the most favorable for working in extreme environmental conditions due to their superior heat resistance and durability. Researchers have recently focused more on the development of reinforced thermoplastic composites. The specific challenges faced by researchers and engineers when developing high-temperature composites include maintaining structural integrity and mechanical properties under extreme conditions. The specific techniques used by researchers to modify and reinforce high-temperature thermoplastics for enhanced performance include the use of advanced nanofillers and their dispersion methods, fiber reinforcement strategies, flame retardant formulations, and toughening agent incorporation. The research has shown promising results in improving the mechanical, thermal, and physical performance of thermoplastics composites. However, challenges remain in predicting the long-term performance and durability of high-temperature thermoplastics in aerospace and automotive environments. These materials are essential for applications requiring thermal and chemical resistance, but their deployment in critical environments exposes them to conditions that can lead to fatigue failure through different mechanisms. These mechanisms include oxidation, thermal degradation, matrix crystallinity changes, fiber-matrix interface degradation, residual stresses, creep, and microcracking. This article aims to review the approaches various authors have adopted to ana

关键词： Durability

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Influence of Superplasticizer on Workability and Early Strength of Fly Ash/Blast Furnace Slag Based Geopolymer Mortar 2nd

Influence of Superplasticizer on Workability and Early Stren...

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2nd International Conference on Sustainable civil engineering and Architecture, ICSCEA 2021

作者： Indriani, Kemala Saludung, Apriany Ogawa, Yuko Kawai, Kenji Civil and Environmental Engineering Program Graduate School of Advanced Science and Engineering Hiroshima University 1-4-1 Kagamiyama Higashihiroshima Japan Department of Civil and Environmental Engineering Graduate School of Engineering Hiroshima University 1-4-1 Kagamiyama Higashihiroshima Japan

ISBN: (纸本)9789811933028

Recent studies have shown the presence of ground granulated blast-furnace slag (GGBS) in fly ash based geopolymer induced denser microstructures and better compressive strength. However, the inclusion of GGBS gives rapid setting time despite its benefit in terms of mechanical properties and could cause difficulty in handling the geopolymer in its application such as troubles with delivery time of fresh mix geopolymer concrete. This study aims to investigate the effect of polycarboxylate based superplasticizer, which is commonly used in Portland cement concrete to improve the workability and achieve appropriate compressive strength, on the fresh properties and early strength of geopolymer mortar. Geopolymer mortar was composed of fly ash and GGBS acting as binder with sodium silicate and 12 M of sodium hydroxide solution as alkaline activator. Alkaline to binder and fly ash/GGBS ratios were kept constant at 0.5 and 1.5, respectively. Superplasticizer was added into alkaline solution before casting at various dosages of 0%, 1%, 2%, 4%, and 8% by the binder mass and all the specimens were cured in two regimes of heat curing and 20ºC curing. The results have shown that the inclusion of superplasticizer maintained the workability over the time and may delay the setting of geopolymer mortar. Moreover, the mixture with 8% superplasticizer had dense microstructure and comparable compressive strength to that without superplasticizer at the age of 7 days. © 2023, The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd.

关键词： Compressive strength

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Applicability of Electrical Resistance Method to Moisture Transfer Measurement in Paste Using Mineral Admixture 2nd

Applicability of Electrical Resistance Method to Moisture Tr...

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2nd International Conference on Sustainable civil engineering and Architecture, ICSCEA 2021

作者： Aoki, Takahiro Ogawa, Yuko Kawai, Kenji Civil and Environmental Engineering Program Graduate School of Advanced Science and Engineering Hiroshima University 1-4-1 Kagamiyama Higashihiroshima Japan

ISBN: (纸本)9789811933028

Concrete is a porous material which has the ability to hold moisture stably inside. Since moisture is closely related to the deterioration of concrete structures, it is important to understand the moisture transfer in concrete in order to maintain the concrete structure appropriately. The electrical resistance method is one of non-destructive methods to investigate the moisture in concrete and the moisture transfer can be assessed with time by using one specimen. However, the electrical resistance may be affected by mineral admixtures in concrete. Although previous studies on the effects of mineral admixtures on the electrical resistance have been conducted, there are still many unclear points. Therefore, the purpose of this study is to assess the applicability of the electrical resistance method to moisture transfer measurement in paste containing mineral admixtures by focusing on the moisture transfer in the drying process. The moisture transfer in the hardened cement paste using fly ash and blast furnace slag with water-to-binder ratios of 0.35 and 0.55 was investigated by the electrical resistance method. Stainless steel rods of 0.9 mm in diameter were placed at an interval of 4 mm in the specimen. The calibration test was also conducted to obtain the relationship between the electrical resistivity and the internal relative humidity of the specimen. The result showed that the specific resistance of the specimen containing mineral admixtures was higher than that of the specimen without mineral admixtures. It was observed that at the drying period of 70 days, the internal relative humidity at a depth of 4 mm from the exposed surface was almost the same as the surrounding relative humidity. It is possible to know the change in the internal relative humidity distribution in the cement paste using mineral admixtures during the drying process by performing the calibration test appropriately. © 2023, The Author(s), under exclusive license to Springer Nature Singapore P

关键词： Concretes

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Unsaturated Strength of Tage Tuff and Its Water Retention Drying Curve

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Zairyo/Journal of the Society of Materials Science, Japan 2024年第3期73卷 212-219页

作者： Kotabe, Haruhiko Togashi, Yota Hatakeyama, Ken Osada, Masahiko Civil and Environmental Engineering Program Graduate School of Science and Engineering Saitama University Shimo-Okubo Sakura-ku Saitama338-8570 Japan Integrated Technical Support Center Research Organization Saitama University Shimo-Okubo Sakura-ku Saitama338-8570 Japan

Strength loss of sedimentary rocks due to water content changes is an important issue in the civil engineering field. Assuming disasters associated with rainfall and drying, it is important to identify unsaturated strength properties for gradually varying moisture contents. Water retention curves are needed to describe unsaturated strength properties. The high suction acting in the case of rock presents a challenge in identifying the suction. In particular, identifying the water retention drying path is difficult. This study propose a method to identify the drying paths using uniaxial compressive strength and tensile strength of Brazilian test. Uniaxial compression and Brazilian tests were performed on specimens with varying water content in the drying pass to investigate changes in their mechanical properties. Strength and stiffness were found to be approximately halved in the wet condition compared to the dry condition. Simplified Mohr-Coulomb failure criteria are also identified using uniaxial compressive and tensile strength. The cohesion decreases with increasing water content, while the angle of shear resistance is independent of changes in water content. Suction at each saturation level was back-analyzed using the detected cohesion and shear resistance angles to identify the water retention drying curve. The water retention drying curves identified were compared with the water retention wetting curve identified by another method to confirm the validity of the proposed method. ©2024 The Society of Materials Science, Japan.

关键词： Sedimentary rocks

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Modal analysis under jittering and kernel clock distribution: single-output identification

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Proceedings of the Institution of civil Engineers: Smart Infrastructure and Construction 2023年第4期177卷 224-235页

作者： Ramadan, Wasim Ozer, Ekin Sustainable Environment and Energy Systems Program Middle East Technical University Northern Cyprus Campus Turkey School of Civil Engineering University College Dublin Dublin Ireland

Smartphones have attracted attention in the structural health monitoring community due to their embedded multisensory platforms suitable for crowdsourcing innovation. Despite their advantages, smartphone sensors are originally designed for user utility rather than technical engineering applications (e.g. vibration analysis and modal identification). Sampling jitter is among those problems adversely influencing smartphone performance as a scientific device that can be used for characterising civil infrastructure dynamic characteristics. With inconsistencies in the sampling period due to jitter effects, the identified modal frequencies of a structure can deviate from the actual value, which is artificially introduced by smartphone clock errors. In this study, the authors formulate the statistical characteristics of the smartphone sampling period through kernel distribution and apply a digital reconstruction remedy to the sampling jitter problem. Through introductory simulations of a sine wave and physical implementations through shaking table tests equipped with smartphones, the efficiency of kernel distribution diagnosis and the signal-reconstruction remedy is presented. Following the simulation and laboratory applications, the proposed techniques are applied to vibration monitoring of a steel pedestrian bridge in terms of the auto power spectral density and short-time Fourier transform of single-output signals. The results show successful rehabilitation of accelerometer data from smartphones, removing jitter-induced errors to a significant extent and accordingly improving the identification accuracy currently in a single-output setting. © 2023 Emerald Publishing Limited: All rights reserved.

关键词： Vibration analysis

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NONLINEAR FINITE ELEMENT MODELING OF PRESTRESSED LEAD EXTRUSION DAMPERS 9

NONLINEAR FINITE ELEMENT MODELING OF PRESTRESSED LEAD EXTRUS...

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9th ECCOMAS Thematic Conference on Computational Methods in Structural Dynamics and Earthquake engineering, COMPDYN 2023

作者： Çalim, F. Güllü, A. Soydan, C. Yüksel, E. Faculty of Civil Engineering Istanbul Technical University Maslak Sariyer Istanbul34485 Turkey Ingram School of Engineering Texas State University San MarcosTX78666 United States Department of Civil Engineering Tekirdag Namik Kemal University Suleymanpasa Tekirdag59030 Turkey

In the earthquake-resistant design of the structures, supplemental energy dissipative devices have increasingly been utilized for structural response control. The lead extrusion damper (LED) is one of the prominent versions of metallic dampers, as it dissipates high amounts of seismic energy by the extrusion of lead through the displacement of a bulged shaft. Its geometric properties, i.e., length and diameter of the tube, shaft, bulge, and lead, should be designed based on the target performance level of the host structural system. Thus, determining the LED's force-displacement relationship and seismic energy dissipation characteristics becomes essential for a proper design. In this study, the developed three-dimensional finite element modeling (FEM) strategy for the LED is examined through some literature experiments. The comprehensive three-dimensional model was utilized with the exact material characteristics determined through the coupon tests to increase the accuracy of predicting the LED's behavior. The numerical models were verified using the experimental results of the LEDs with different geometries adapted from the literature. The low relative differences between the numerically and experimentally obtained damper forces, i.e., 4.3% mean error, exhibited that the developed modeling strategy can accurately simulate the LED's hysteretic behavior. The consistency of the modeling strategy with different devices' behavior proved the versatility of the developed FEM. In addition, the effects of the different geometric properties on the LED's cyclic behavior were discussed numerically. © 2023 COMPDYN Proceedings. All rights reserved

关键词： Light emitting diodes

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