Code Requirements Research Articles

Experimental study on seismic behavior of RCS joints with asymmetric friction connections and slabs

This paper introduces a new reinforced concrete column-steel beam (RCS) joint that employs asymmetric frictional connections (AFC) to improve energy dissipation and moment transfer, reducing stress concentrations within the joint’s core. Two RCS joint specimens with AFC and floor slabs were designed and tested under quasi-static loading to analyze the impact of bolt preload on seismic performance. The experimental results demonstrate that RCS joints with AFC and slabs exhibit favorable seismic behavior in terms of bearing capacity, energy dissipation, and stiffness degradation. Increasing bolt preload enhances the bearing capacity, stiffness, and energy dissipation capacity of the joints. The failure occurred at the steel beam splice connections, while only minor micro-cracks appeared in the reinforced concrete column when the joint's bearing capacity dropped below 80% of the peak load. Displacement at the column top was primarily influenced by steel beam and column deformation, with minimal contribution from joint core deformation. The use of AFC effectively reduced deformation in the joint core area, meeting seismic design code requirements for “strong columns-weak beams.”

A research on the Turkish shipyards in the Arctic: Opportunities and challenges

The Arctic region has been experiencing an extensive transformation and several economic opportunities have emerged due to the shrinking sea ice. While the Arctic Ocean has become more convenient for navigation, both Arctic and non-Arctic states have updated their Arctic policies according to recent developments. There has been a substantial increase in the number of studies studying three main Arctic sea routes: Northwest Passage (NWP), Northeast Passage (NEP), and Trans-Polar Sea Route (TSR). Albeit the existence of contradictory results, the interest in Arctic shipping presents a growing trend. The Turkish shipyards increasingly participate in tenders as well. While Çelik Tekne Shipyard stands out as the first Turkish shipyard to win the shipbuilding tender in accordance with polar conditions, a significant increase has been observed in the number of shipyards within the Arctic shipping tenders since 2018. In addition to Atlas and Akdeniz Shipyards, producing ice-class vehicles in accordance with the requirements of the Polar Code, it is possible to multiply examples from Beşiktaş Shipyard, which built ice class fuel ships, Sanmar Shipyard, which won the icebreaker tugboat tender, and Sefine and Kuzey Star Shipyards, which participated in the icebreaker tenders. Besides, the participation of Turkish shipyards as sole contractors in the Russian Arctic as of 2021 indicates their determination to become active actors in the Arctic shipping industry. Accordingly, this paper discusses the opportunities and challenges of Arctic shipping based on the Turkish case.

Monitoring and Analysis of Prestress Loss in Prestressed Box Girder Bridges Strengthened with External Prestressing.

To investigate the effects of long-term prestress loss on concrete box girders strengthened with external prestressing, a large-span box girder, in service for over 20 years and strengthened with external prestressing, was monitored for four months. Prestress loss in the longitudinal, vertical, and transverse directions of the box girder was calculated according to Chinese code requirements. Magnetic flux rope force transducers were used to monitor the prestress loss in the external prestressing cables. Fiber Bragg Grating (FBG) sensors were used to monitor deflection changes at the mid-span of the bridge. Finally, the effect of prestress loss in the longitudinal, vertical, and transverse tendons on mid-span deflection was investigated through simulations using ABAQUS software. The results show that instantaneous prestress loss accounts for most of the total loss compared to long-term loss, and that longitudinal prestress loss has the most significant effect on mid-span deflection. The impact of longitudinal prestress loss on deflection before and after strengthening was also compared. The downward deflection and up-ward arch caused by longitudinal tendon prestress loss were reduced after strengthening, con-firming the effectiveness of the external prestressing method.

Investigation of the Impact of Fault Characteristics on the Cost-Effectiveness of Doubly Fed Induction Generator-Based Wind Systems in Withstanding Low-Voltage Ride-Through

Wind farms utilizing doubly fed induction generators (DFIGs) can have a significant impact on the stability of power networks as both the stator and rotor of the DFIG are linked to the grid, which can result in excessive overcurrent and overvoltage in the event of a grid fault and can activate the protective mechanism, leading to the disconnection of the WF and generating instability in the system. One term that is often mentioned in the literature is low-voltage ride-through (LVRT) capability, which is crucial to the stability of microgrids (MGs). To handle LVRT, advanced protection schemes or supporting devices are required. In addition, MGs must comply with the operational limits imposed by different countries for LVRT. Therefore, numerous solutions for improving LVRT have been proposed, including external approaches that are expensive to adopt and internal procedures that provide economic gains but are more difficult to apply. Consequently, to help lower the cost of installing WFs, the study investigates how fault characteristics affect MGs’ ability to meet grid LVRT code requirements or even choose the right code to be used. It also aims to give a clear understanding of how fault characteristics affect the grid’s behavior during different types of faults, which will be helpful in choosing the best LVRT-enhancing method or device and for determining the optimal ratings for these devices, and thus reduce the cost of installation. The study offers case studies and simulations using Matlab 2024/Simulink, which could help engineers to ensure reliable grid integration of renewable energy sources in a cost-effective manner.

Grid impact analysis on wind power plant interconnection in strengthening electricity systems

The Timor system is one of the large systems in the East Nusa Tenggara region. Based on the general plan for electricity supply for 2021-2030, there is a plan to interconnect a 2x11 MW wind power plant. The addition of wind power plants will pose a considerable threat to the system due to the intermittency nature of renewable energy plants. Therefore, a comprehensive grid impact study is needed to convince network managers that adding wind farms will not cause disruptions to the system either locally or in general and is expected to strengthen the electricity system. The power flow simulation results, installing a 2x11 MW wind farm on the Timor system can improve voltage quality and reduce losses on both 70 and 150 kV systems. For transient stability, the frequency value on the Timor system still meets the grid code requirements. In addition, the simulation results of the intermittency impact of the wind power plant output show that the Timor system is still in a stable condition. The stability of the rotor angle of the existing power plant when the transient stability simulation is carried out shows that it is still in a balanced condition.

Quantifying the electric service panel capacities of California's residential buildings

This study seeks to quantify the size distribution of existing installed electrical service panels within California's residential buildings, a potentially significant barrier to future decarbonization efforts. A large sample of historical building permit data was collected for municipalities throughout the state, from which permitted panel upgrades were extracted and analyzed. These data were used to develop a method for estimating panel capacities that incorporates information about historical code requirements for panel sizing in new construction with a statewide database of parcel-level building attributes. Overall, we find that 3% of single-family (SF) and 10% of multi-family (MF) properties in California have panels in the smallest size range, which will most likely require upgrades. However, 32% of SF and 59% of MF properties have panels of intermediate size, which will likely require the addition of load management systems to support comprehensive electrification. Future panel upgrade needs are expected to be more acute within disadvantaged communities, where the proportion of SF homes with the smallest-sized panels is 4x that in more affluent neighborhoods. We discuss the implications of these and other results within the context of existing and planned future state policies related to residential electrification.

Intergenerational Judo: Synthesising Evidence- and Eminence-Based Knowledge on Judo across Ages.

In alignment with European policies regarding intergenerational sports, this study seeks to integrate existing evidence- (i.e., umbrella review) and eminence- (i.e., international validated educational courses for coaches) based knowledge on judo training across the lifespan. For evidence knowledge, searches of the Google Scholar, ISI-WoS, PubMed, and Scopus databases (PROSPERO ID: CRD42024535420) for studies focused on training youth and older judo practitioners, with no time restriction up to April 2024, were conducted. This resulted in 16 systematic reviews meeting the inclusion criteria, with an "excellent" (n = 6), "good" (n = 7), and "fair" (n = 3) quality according to the NIH tool. With a large sample size (n = 372,655), the reviews focused on wellbeing (n = 9; bone status, injuries, and psychophysical effects) and performance (n = 7; athlete success, combat time, rapid weight loss, and the Special Judo Fitness Test), examining athletic levels (novices to Olympics), sex, and age (children to older adults). For eminence knowledge, the International Judo Federation Academy courses encompassed the "Undergraduate Certificate as Judo Instructor" (UCJI), which provides a comprehensive structure for teaching judo, including techniques, moral code, roles, responsibilities, refereeing, safety, and age-specific belt examination requirements and progression, and the "Educating Judo Coaches for Older Practitioners" (EdJCO) curricula, which provide theoretical and applied modules (e.g., ageing, health, and organisation) to train older judo practitioners. The findings were summarised in a framework, highlighting the most relevant aspects of intergenerational judo programmes (i.e., aims, key characteristics, coaches' roles, barriers, and facilitators). To develop a comprehensive educational intergenerational judo methodology, future research should examine coaches' and practitioners' opinions on intergenerational judo activities carried out in different national contexts.

Hygrothermal Performance of Roofs with High Initial Construction Moisture Subjected to Hot Climate

Moisture accumulation in the building components/assemblies that form building envelopes can lead to material deterioration and moisture related issues such as mould growth. As a part of the building envelope, this study focusses on assessing the moisture performance and energy performance (i.e., hygrothermal performance) of roofing systems. As roofs can be built with high initial construction moisture, numerical simulations were conducted with and without high initial construction moisture in order to investigate: (a) the hygrothermal performance of cool and black roofs having material layer with high initial construction moisture content, (b) the time needed so that the moisture content reaches acceptable level as per the building code requirements, (c) whether moisture accumulation and mould growth occur in the roofs, and (d) the energy savings as a result of installing white/cool roof instead of black roof. An advanced numerical model is used to conduct the numerical simulations for black and cool roofs when they are subjected to hot climate. This model solves simultaneously the Heat, Air and Moisture (HAM) transport equations in all layers of the building assemblies. The model was extensively validated by comparing its predictions with the experimental data of different building components at various operating conditions. For the roofing systems investigated in this paper, the results showed that mould growth occurred in the black and cool roofs only for the case with high initial construction moisture. The mould has totally disappeared after 378.8 day for the black roof and 479.3 day for the cool roof. The temperatures of the cool roof were much lower than those for the black roof. The total yearly energy load with the black roof was 77% greater than that with the cool roof.

Design and optimization analysis of pylon open lower corbel

This study, centered around the engineering context of the Wuxue Yangtze River Bridge, addresses the challenge of significant temperature-induced secondary internal forces in the short lower tower column. A novel open lower corbel tower scheme is proposed as a solution. Firstly, comprehensive finite element models are established for both the open lower corbel pylon scheme and the traditional lower continuous beam pylon scheme. These models are employed for finite element analysis to derive bending moments and displacements of the bridge pylon under various loads, including permanent, vehicle, temperature, and wind loads. Subsequently, considering internal force distribution and stiffness, a comparative assessment is made between the open lower corbel cable pylon scheme and the traditional lower continuous beam cable pylon scheme. The findings reveal that the open corbel structure bridge pylon exhibits lower transverse bending moment values under the influence of permanent load, vehicle load, temperature load, and wind load. This reduction is advantageous for mitigating the issue of significant temperature-induced secondary internal forces in the bridge pylon. Additionally, the transverse bridge stiffness of the open lower corbel cable pylon scheme is found to be on par with that of the lower continuous beam cable pylon scheme. Moreover, topology optimization of the original corbel design is accomplished using the relative density method. The computational results demonstrate that the corbel’s stress and deformation under vertical loads meet code requirements. These research findings offer valuable insights for the design and construction of similar projects.

A comparative study of emerging material point method and FEM for forming simulation of textile reinforcements

For forming simulations of fabric composites, nonlinear Finite Element Method/FEM has been a long-standing tool to predict and mitigate defects such as wrinkling. However, small-time step requirements in explicit FEM codes, numerical instabilities, and large computational time are among challenges reported. This study presents an alternative fast forming simulation technique through an application of the so-called Material Point Method/MPM, which enables the use of much larger time steps along with fewer numerical instabilities. As a preliminary step towards assessment of this method, both standard 2D deformation modes and 3D hemispherical forming setups were employed, using a plain fabric weave at dry condition. The MPM results were compared to the conventional FEM simulations, as well as to the physical experiments. Notably, the MPM method showed a runtime 20 times faster than its FEM counterpart (under a comparable mesh size), yet with the same reliability in forming predictions as verified by experiments.

Database of tall pre-Northridge steel moment frames for earthquake performance evaluations

This article describes a detailed database of tall steel moment frame buildings that are representative of the construction practices in San Francisco prior to the 1994 Northridge earthquake. The database contains design details that affect the structural performance of steel moment frames, including frame geometry, member cross-section sizes, and gravity system characteristics. This database also captures irregularities that might impact seismic response, such as podiums, setbacks, mass concentrations (mechanical, electrical, and plumbing (MEP) floors), interrupted column lines, and atriums. The database includes information on 89 moment frame buildings, 14 of which were built before 1960 and are constructed with riveted connections, while the remaining 75 have welded flange connections like those that suffered brittle fracture during the 1994 Northridge earthquake. The buildings are further distinguished between space frame, perimeter frame, and partial space frame systems. For about half (41/89) of the buildings in the database, section sizes of representative structural members were collected, which enabled the evaluation of the seismic design, elastic, and inelastic response using computational workflows. The design diagnostics indicate that most of the buildings meet the minimum seismic strength and strong-column weak-beam requirements of modern building codes, even though they were not necessarily designed with this intent. On the contrary, about one-third of the buildings do not meet the seismic design drift limit of current codes, and about half of them have weak beam-column panel zones. This database, associated structural analysis models, and processing scripts are published at DesignSafe https://doi.org/10.17603/ds2-wjad-r340 to facilitate collaboration and continued development of open-source data for high-resolution simulations to inform risk mitigation strategies on a regional scale.

Feasibility of production fired bricks based lateritic soil at very low temperature

AbstractThe present project deals with the production of lateritic soil based bricks under different curing temperatures (28°C–150°C). A fraction of 10–30 wt% amount alkaline solution was added to improve the reactive phase content. The raw materials and hardened products were characterized using X‐ray diffraction (XRD), fourrier transform infrared spectroscopy (FTIR), mechanical properties and scanning electron microscope analysis. The results show that the addition of alkaline solution (30%) and the curing temperature (150°C) have a beneficial influence on physical properties (bulk density: 1.77 g/cm3, water absorption: 16.98%, and porosity: 30.13%) and mechanical performances (flexural: 6.61 MPa and compressive: 13.57 MPa). Compared with the code requirements for stabilized earth blocks, the compressive strength was higher than the minimum required. Microstructural investigations were also carried out to confirm the macrostructural properties. The above‐mentioned process appears to be a suitable candidate for engineering applications such as the stabilization of earth roads.

Analysis of Wind Load in a 15-Storey Building Using Various Lateral Load Resisting Techniques: A Review

Traditionally, outrigger and belt truss additions are used to strengthen the rigidity of tall buildings with central cores in order to control displacements. At the top of the structure, a single level outrigger can efficiently reinforce a building. The lateral stiffness of each outrigger level rises, although not as much as that of the top level. The primary lateral force-resisting elements of high-rise building structures are shear walls. Higher-performance shear walls are necessary because to the ever-increasing building code requirements and the rising height of high-rise and super high-rise structures. The conventional reinforced concrete shear wall is not very ductile, has a limited capacity to dissipate energy, and is not very deformable. Specifically, the base of a typical shear wall is particularly vulnerable to earthquake damage and is highly challenging to restore. In high-rise and super high-rise buildings, steel plate shear walls (SPSWs) and steel plate reinforced concrete composite shear walls (SPCSWs) are frequently used in place of regular reinforced concrete shear walls or shaped steel reinforced concrete composite shear walls to improve the seismic performance of building structures. Numerous structural methods seem to be able to withstand lateral stresses brought on by earthquakes, blasts, and wind. The more crucial it is to choose the optimal structural arrangement to counteract opposing horizontal loads. Keywords— High-rise structure, Outrigger, Shearwall, Damper etc.

Behavior of Lightweight Aggregate Wide Reinforced Concrete Beams with Shear Steel Plates Under Repeated Loading

Abstract This study describes an experimental research focusing on the behaviour of Lightweight Aggregate Wide Reinforced Concrete Beams (LAWRCB) using shear steel plates. This technique represents an inexpensive way which reduces structural and building complexities. Wide beams can provide adequate cross-sectional areas to meet the specified capacity in a shallower depth than a system of narrower beams placed similarly in the design. Also, WB treats the crowd of stirrups because the shear component provided by concrete is very small compared with high depth concrete Beams. This research is also trying to minimize the weight of a wide concrete beam using light weight concrete instead of using conventional concrete which has effects on the deflection, crack patterns, and load carrying capacity. This investigation consists of reviewing the previous work and an experimental program consisting of testing mixes to produce lightweight concrete. In addition, several simply supported wide beams with various parametric studies will be designed, cast, and tested. After the specimen tests are carried out, comparisons and discussions of the results will be made with code requirements.

A Conceptual Study of Wind Load With Different Types of Lateral Load Resisting Methods in 15-Storey Structure

Abstract: In order to strengthen rigidity and control the base deflection of a high-rise structure, stabilizers and trusses are typically used. A stabilizing layer on the building's roof efficiently fortifies the structure. Lateral stiffness is increased by each succeeding stabilizer layer, albeit less so than by the preceding stabilizer layer. The essential components in multi-storey buildings that can withstand shear forces are the shear walls. More efficient shear walls are required as building code requirements rise and tall structures and skyscrapers get taller. The ductility, energy dissipation capacity, and deformation capacity of conventional reinforced concrete shear walls are limited. In the field of structural engineering, a damper in a building is a device intended to lessen the impact of dynamic forces like seismic vibrations or oscillations caused by wind. These devices are necessary in tall or flexible constructions where excessive movement may cause structural damage or cause discomfort for the residents. In this research, we prepare four different cases of 15-storey structure. All modeling work performed in ETABS 2016. Material properties use concrete grade M-40 and steel grade Fe375 and Fe250. One case has shear walls on corners, second case have FVD damper on corners and last case have outrigger on corners. For design wind speed data use code IS: 875-(2015).

Effect of steel slag and aspha-min zeolite on moisture susceptibility and stiffness of asphalt concrete mixes

This study evaluates the laboratory performance of Warm-Mix Asphalt (WMA) containing locally sourced Steel Slag (SS) and limestone (LS), focusing on stiffness and moisture sensitivity. Four asphalt mixes were tested: Hot mix with limestone (HL), hot mix with steel slag (HS), warm mix with limestone (WL), and warm mix with steel slag (WS). The binder used for all mixes was AC 60/70 penetration grade, and Aspha-min served as the warm mix additive.Testing included Marshall Stability, boiling water, indirect tensile strength, moisture-induced damage (TSR), and dynamic modulus. Image Analysis quantified the aggregate-retained coated area after the boiling test. Despite performance differences, all mixes met Egyptian code requirements for asphalt concrete mixes.Visual inspection and image analysis demonstrated the effectiveness of using steel slag to mitigate asphalt mix stripping. The retained coated area for limestone mixes ranged from 60 % to 75 %, while SS mixes exhibited over 95 %. Dynamic modulus tests indicated no significant stiffness difference with SS, and stability increased by 8 % and 14 % with and without the warm additive. Economic study confirmed the feasibility of utilizing SS. In conclusion, combining Aspha-Min and steel slag improves AC mix production and construction processes, offering a sustainable and advantageous option in Egypt.

Arab minority social workers trained in a foreign language: linguistic challenges and coping mechanisms

ABSTRACT The research highlights challenges involved in ensuring professional authentication faced by social workers working in cultural minorities. The findings contribute to the knowledge corpus that discusses authentication. They describe and explain possible consequences of linguistic difficulties arising in Arab minority social workers’ work in Israel. These workers acquired their profession in a foreign language (Hebrew) but work with their native minority population whose mother tongue is Arabic. A phenomenological study elicited data from semi-structured in-depth interviews with 19 Arab welfare bureau social workers. The workers encounter three language difficulties when working with their service users: They are accused of identifying with the hegemon because they adopt its language; they are viewed as foreign because they have difficulty conveying professional messages accurately; and are seen as alien because the Hebrew terminology they use is anchored in a secularist-individualist culture. The research also identified three coping mechanisms: Ignoring the language barriers; being aware but passive, and adopting three active strategies: self-improvement, getting help from the immediate professional milieu and harnessing external resources. The findings reinforce the requirement of ethical codes for language competence in three fields: lifelong learning, policy design (laws, procedures and guidelines) and implementation (interventions, mentoring and supervision).

Hybrid surrogate model combining physics and data for seismic drift estimation of shear‐wall structures

AbstractTo address the issue of costly computational expenditure related to high‐fidelity numerical models, surrogate models have been widely used in various engineering tasks, including design optimization. Despite the successful application of the existing surrogate models, physics‐based models depend largely on simplifications and assumptions, which render parameter calibration challenging; whereas data‐driven models require substantial data to reach their full potential, with their performance often being constrained in tasks when obtaining massive data is difficult. In this study, a hybrid surrogate model is proposed combining physics‐based and data‐driven models to rapidly estimate building seismic responses. The application of this model is exemplified through effective estimation of inter‐story drift ratios (IDRs), being a critical factor in shear‐wall structure design. Initially, a data augmentation technique and a parametric modeling procedure are introduced to significantly enhance the dataset diversity. Subsequently, a task decomposition strategy is proposed to effectively integrate a data‐driven graph neural network (GNN) and a physics‐based flexural‐shear model. Additionally, the output layer and the loss function of the GNN are modified to enhance the estimation accuracy by eliminating fundamental errors. Results of numerical experiments indicate that the proposed hybrid model can complete IDR estimations in an average time of 0.56 s, with a mean absolute percentage error of 12.7%. This performance significantly surpasses that of existing purely data‐driven and physics‐based models. A case study shows that the efficiency of the proposed hybrid model is approximately 100 times greater than that of conventional finite element software. This enables an accurate assessment of the design compliance with code requirements. The results of this study can be applied to the design optimization of seismic‐resistant building structures.

Novel risk index integrating practical operation limits enhances probabilistic contingency ranking for large-scale photovoltaic plant planning

This research addresses the pressing need for heightened grid security amid increasing uncertainties in photovoltaic PV generation. The research problem lies in the limitations of conventional contingency analysis metrics, failing to adequately consider both contingency occurrences and uncertainties inherent in PV generation. In response, a comprehensive algorithm is proposed that introduces a novel severity function framework, enhancing traditional contingency ranking metrics. This approach incorporates grid remedial actions and refines line and bus voltage classification by considering available correction time, aiming to offer a more robust security assessment. Motivated by the imperative to address uncertainty in PV generation, the proposed work builds on established analysis tools. A probabilistic load flow algorithm manages PV generation uncertainties, utilizing historical data for contingency incidence uncertainty. Additionally, a probabilistic model for PV plants integrates historical solar data, deriving hourly probability density functions to meet grid code requirements, including reactive power considerations. The justification for this work lies in the algorithm's demonstrated efficacy, validated on the IEEE 14-bus network. Results highlight its ability to identify risks associated with line overloading and bus voltage breaches. Comparative evaluations underscore proper coupling buses for security, favoring distributed capacity to mitigate line overloading risks. The study's key results emphasize voltage risk amplification with reactive power omission, stressing the significance of compensation strategies. This research addresses a critical problem, presenting a comprehensive algorithmic solution to enhance grid security amidst uncertainties in PV integration. Findings offer valuable insights for strategically interaction between large scale PV plants and electrical grid, contributing to an improved grid security paradigm in a dynamic and uncertain energy model.

STUDY ON CONSTRUCTION MONITORING AND CONTROL OF MULTI-SPAN PRESTRESSED CONCRETE CONTINUOUS BEAM BRIDGE

This article focuses on the construction monitoring and control of a pre-stressed concrete continuous beam bridge, consisting of 13 spans. The goal is to ensure that the bridge structure meets the design requirements throughout the entire construction process. By comparing the theoretical and measured values of the bridge’s alignment and stress during the cantilever construction, closure, and completion phases, it can be observed that the deflection deformation of the bridge is generally in agreement with the theoretical calculations. After the completion of the entire bridge, the measured elevations of each section have an error range of -18mm to 20mm compared to the design elevations, which satisfies the specifications. A comparison analysis of the measured and theoretical stress values at the root and mid-span of the cantilever indicates that the stress difference at the root is within the range of -0.2MPa to 0.2MPa, and the stress differences at the mid-span after completion are 0.03MPa (upper) and 0.09MPa (lower), all of which meet the structural design and code requirements. By establishing a gray GM (1,1) model and using gray system theory, the deflection error during the construction process is predicted and controlled. The prediction accuracy of different methods is compared to determine a reasonable prediction method suitable for long-span pre-stressed continuous beam bridges, providing reference for similar engineering projects.