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The tensile creep of concrete with supplementary cementitious materials (SCMs) such as fly ash (FA) and ground granulated blast furnace slag (GGBFS) is investigated in this paper. A total of 21 series of tensile creep tests using dog-bone specimens under uniaxial tensile loading have been carried out. The cement replacement rates considered were 30% fly ash, 40% and 60% GGBFS. The characteristic compressive strength of concrete was ranging from 25 to 100 MPa. The tests were conducted from the age of 2 days until 28 days. It is observed that the tensile creep of fly ash concretes was slightly lower than that of the reference mixtures without SCM. For GGBFS concrete, the higher the GGBFS content, the higher the tensile creep. Existing creep models, originally developed for creep in compression, could not predict the experimental tensile creep results. Thus, a new tensile creep model was proposed including creep prediction for concrete with fly ash and GGBFS. The new model was calibrated only for controlled environmental conditions (23°C and 50% RH) and has been validated by analyzing the development of concrete tensile stress in the restrained ring test.

The problem of creating unwanted fractures while drilling ultradeep wells is mitigated with the application of wellbore strengthening techniques. Despite the numerous applications, an open question remains about the efficiency of the loss of circulation materials (LCM) and its implications on the closure stress distribution change during plugging. This work investigates the effects on the stress field before and after plugging along the fracture extension axis by introducing a hydrodynamic plug. With the hydrodynamic plug, fluid flow is constrained by pressure conditions at specific locations in the fracture simulating the LCM. Three different scenarios were considered. First, the efficiency of the bridge is simulated by varying the pressure drop. Second, the location of the bridge inside the fracture and finally a nearly packed fracture. The models are fully coupled and were solved with the finite element method in impermeable and permeable hard rocks. We find that for high-efficiency bridges, narrower fracture profiles are predicted, which causes the induced closure stresses to increase significantly. On the other hand, when the bridge is close and near the wellbore area, the fracture profiles are maintained wide and narrow when it is nearest to the tip. The predicted fracture geometry induces higher closure stresses when the plug is near the well and slightly reduces when it is near the tip. Finally, the pressure profile resulting from the packed fracture significantly affects the fracture dimensions, resulting in narrower fracture, however resulting in a smooth variation of induced closure stresses with high magnitude comparable to the stresses at the state of propagation. The diffusion occurring in the permeable case creates back-stresses that appear to have an additive contribution to the induced closure stresses. This underlines the significance of diffusion on the induced coupled closure stresses for large fractures while performing wellbore strengthening methodologies.

The extensive disposal of plastic components into the environment requires an economically and ecologically feasible solution for the proper treatment or new uses for plastic waste. This study compares the environmental and mechanical performance of a sandwich panel based on disposed bottle caps core with different eco-friendly skins and adhesive. A cradle-to-gate life cycle assessment compares the environmental impacts of the manufacture of six-bottle cap panel designs with various skin (aluminum, recycled PET, and flax laminates) and adhesive types (epoxy vs. biopolymer) by calculating their ReCiPe midpoint impact indicators. An eco-mechanical indicator is additionally proposed to measure the efficiency of designs with greater strength/stiffness and less environmental footprint. The bio-based skin on the sandwich panel significantly reduces environmental damage between 32% and 87% compared to metallic skins. Recycled skin promotes the lowest impacts, while considerably reducing mechanical performance. The bio-based adhesive has emissions up to 15% lower than epoxy. The eco-mechanical balance showed up to 630% higher efficiency for bottle cap panel designs based on bio-based polymer, flax-based skins, and/or less adhesive depending on the mechanical response. Promising environmental performance with superior mechanical strength highlights the potential of bottle caps as an eco-friendly honeycomb for secondary construction and transport structures.

Author(s): Kim, S; Chiang, JCH | Abstract: The range of synoptic patterns that North Pacific landfalling atmospheric rivers form under are objectively identified using genesis day 500 hPa geopotential height anomalies in a self-organizing map (SOM). The SOM arranges the synoptic patterns to differentiate between two groups of climate modes—the first group with ENSO (El Nino Southern Oscillation), PDO (Pacific Decadal Oscillation), PNA (Pacific North American) and NP (North Pacific index) and the second group with AO (Arctic Oscillation), EPO (East Pacific Oscillation), and WPO (West Pacific Oscillation). These two groups have their positive and negative modes organized in opposite corners of the SOM. The ARs produced in each of the synoptic patterns have distinct lifecycle characteristics (such as genesis and landfall location, duration, velocity, meridional/zonal movement) and precipitation impacts (magnitude and spatial distribution). The conditions that favour AR trajectories closer to the tropics tend to produce higher amounts of precipitation. The large-scale circulation associated with AR genesis shows a close relationship between the genesis location and the location and intensity of the upper-level jet in the west/central pacific as well as anomalous, low-level southwesterly winds in the east pacific.

The latest release of MODFLOW 6, the current core version of the MODFLOW groundwater modeling software, debuted a new package dubbed the "mover" (MVR). Using a generalized approach, MVR facilitates the transfer of water among any arbitrary combination of simulated features (i.e., pumping wells, stream, drains, lakes, etc.) within a MODFLOW 6 simulation. Four "rules" controlling the amount of water transferred from a providing feature to a receiving feature are currently available. In this way, MVR can represent natural connections between features, for example, streams entering or exiting lakes, and perhaps more interestingly, it also can transfer water among simulated features to more accurately simulate water management. An example model representative of an agricultural setting demonstrates some of the available MVR connections. For example, an irrigation event that transfers surface water from an irrigation delivery ditch to multiple cropped areas demonstrates a "one-to-many" connection that is possible within MVR. Conversely, irrigation or precipitation runoff from multiple fields may be routed to a particular stream segment using "many-to-one" MVR connections. MVR supports many additional connection types, several of which are demonstrated by the included example problem.

Isotopic information from 81 snowpits was collected over a 5-year period in a large, Colorado watershed. Data spans gradients in elevation, aspect, vegetation, and seasonal climate. They are combined with overlapping campaigns for water isotopes in precipitation and snowmelt, and a land-surface model for detailed estimates of snowfall and climate at sample locations. Snowfall isotopic inputs, describe the majority of δ18O snowpack variability. Aspect is a secondary control, with slightly more enriched conditions on east and north facing slopes. This is attributed to preservation of seasonally enriched snowfall and vapour loss in the early winter. Sublimation, expressed by decreases in snowpack d-excess in comparison to snowfall contributions, increases at low elevation and when seasonal temperature and solar radiation are high. At peak snow accumulation, post-depositional fractionation appears to occur in the top 25 ± 14% of the snowpack due to melt-freeze redistribution of lighter isotopes deeper into the snowpack and vapour loss to the atmosphere during intermittent periods of low relative humidity and high windspeed. Relative depth of fractionation increases when winter daytime temperatures are high and winter precipitation is low. Once isothermal, snowpack isotopic homogenization and enrichment was observed with initial snowmelt isotopically depleted in comparison to snowpack and enriching over time. The rate of δ18O increase (d-excess decrease) in snowmelt was 0.02‰ per day per 100-m elevation loss. Isotopic data suggests elevation dictates snowpack and snowmelt evolution by controlling early snow persistence (or absence), isotopic lapse rates in precipitation and the ratio of energy to snow availability. Hydrologic tracer studies using stable water isotopes in basins of large topographic relief will require adjustment for these elevational controls to properly constrain stream water sourcing from snowmelt.

This study utilizes satellite data to investigate water quality conditions in the San Francisco Estuary and its upstream delta, the Sacramento-San Joaquin River Delta. To do this, this study derives turbidity from the European Space Agency satellite Sentinel-2 acquired from September 2015 to June 2019 and conducts a rigorous validation with insitu measurements of turbidity from optical sensors at continuous monitoring stations. This validation includes 965 matchup comparisons between satellite and insitu sensor data across 22 stations, yielding R 2 = 0.63 and 0.75 for Nephelometric Turbidity Unit and Formazin Nephelometric Unit (FNU) stations, respectively. This study then applies remote sensing to evaluate patterns in turbidity during the Suisun Marsh Salinity Control Gates Action ("Gates action"), a pilot study designed to increase habitat access and quality for the endangered Delta Smelt. The basic strategy was to direct more freshwater into Suisun Marsh, creating more low salinity habitat that would then have higher (and more suitable) turbidity than upstream river channels. For all seven acquisitions considered from June 29 to September 27, 2018, turbidity conditions in Bays and Sloughs subregions were consistently higher (and more suitable) (26-47 FNU) than what was observed in the upstream River region (13-25 FNU). This overall pattern was observed when comparing images acquired during similar tidal stages and heights.

The social distancing measure imposed worldwide to combat the outbreak of the novel coronavirus has seen rapid adoption of technologies to support online education. Compared to traditional lecture-based courses, online teaching is particularly more challenging for laboratory courses where hands-on activities are essential to achieve the learning outcomes. To deal with this issue, the study presented in this paper was aimed to: (1) to develop a virtual reality (VR) application to aid a civil engineering laboratory course, and (2) to measure the potential of the VR-aided learning (VRAL) application in civil engineering education by assessing the learners' preferences toward VRAL compared to instructor-aided learning (IAL) and video-aided learning (VAL). Using the Analytic Hierarchy Process, a comparison was conducted with 21 civil engineering students from both undergraduate and graduate levels. The results indicated that VRAL was more preferable than VAL by the participants based on the aspects of “interactivity” (the ability to provide theoretical and practical learning environments to the learners), “cognitive interest” (the ability to drive learners to engage in learning activity), “ease of understanding the content” (the ability to provide a clear lecture interpretation, i.e., easy to understand), and “support for learning” (the ability to help learners to achieve the learning goal). Although VRAL was comparatively less preferable than IAL by the participants overall, it was viewed as better in terms of cognitive interest and “accessibility” (the ability to provide learners with better access to the learning approach in terms of time and location). Complementing previous research, the findings supported the benefits of VR applications to aid civil engineering education.

Buildings and the construction industry are top contributors to climate change, and structures account for the largest share of the upfront greenhouse gas emissions. While a body of research exists into such emissions, a systematic comparison of multiple building structures in steel, concrete, and timber alternatives is missing. In this article, comparisons are made between mass and whole‐life embodied carbon (WLEC) emissions of building superstructures using identical frame configurations in steel, reinforced concrete, and engineered timber frames. These are assessed and compared for 127 different frame configurations, from 2 to 19 stories. Embodied carbon coefficients for each material and life cycle stage are represented by probability density functions to capture the uncertainty inherent in life cycle assessment. Normalized results show clear differences between the masses of the three structural typologies, with the concrete frame approximately five times the mass of the timber frame, and 50% higher than the steel frame. The WLEC emissions are mainly governed by the upfront emissions (cradle to practical completion), but subsequent emissions are still significant—particularly in the case of timber for which 36% of emissions, on average, occur post‐construction. Results for WLEC are more closely grouped than for masses, with median values for the timber frame, concrete frame, and steel frame of 119, 185, and 228 kgCO2e/m2, respectively. Despite the advantage for timber in this comparison, there is overlap between the results distributions, meaning that close attention to efficient design and procurement is essential. This article met the requirements for a gold–gold JIE data openness badge described in http://jie.click/badges.

This chapter presents a comprehensive approach for evaluating the performance of one industrial and one residential smart/near‐zero energy building. The research activities performed and presented in this chapter target the estimation and evaluation of the performance gap between the design and operational phase of zero energy buildings. The steps are as follows: selection of the case study buildings; analysis of the buildings and their systems' design and an assessment of power and energy requirements through dynamic thermal simulation models; data collection while the buildings are in operation; and a comparison of the results of the buildings and the extraction of useful remarks and conclusions. The chapter analyzes the Leaf Lab's energy performance and compares modeling results with real‐time data. There is a systematic and continuous approach in establishing near‐zero energy targets, through research and innovation activities.

A culvert is a covered road structure constructed to pass flood and drainage. The engineering design principle of culverts focuses on optimising flood capacity at the lowest possible cost, resulting in high flow velocity through the barrel. With modern engineering design being more environmentally aware, culverts are considered common barriers for fish migrating upstream due to the excessive barrel velocity. The migration of fish upriver is important for their breeding and feeding activities, contributing to a stable population and species diversity. Improved or novel design for a fish-friendly culvert is needed to ensure well-being of local fish community. This article is a review of recent developments in seeking a solution for a better fish-friendly culvert design. A major common feature of the reviewed studies is the application of hybrid modelling, combining laboratory experiments and numerical Computational Fluid Dynamics (CFD) modelling together. Various design alternatives were compared for pros and cons: channel roughening, installation of speed-reducing structures (e.g., baffles or beams), and simply widening the channel by adding more culvert units (boxes). Overall, channel widening stands to be a better design choice due to its suitability for both flood passage and fish passage, with little impact on operation safety and a reduced maintenance cost.

Effective water resource management requires practical, data-driven determination of instream flow needs. Newly developed, high-resolution flow models and aquatic species databases provide enormous opportunity, but the volume of data can prove challenging to manage without automated tools. The objective of this study was to develop a framework of analytical methods and best practices to reduce costs of entry into flow-ecology analysis by integrating widely available hydrologic and ecological datasets. Ecological limit functions (ELFs) describing the relation between maximum species richness and stream size characteristics (streamflow or drainage area) were developed. Species richness is expected to increase with streamflow through a watershed up to a point where it either plateaus or transitions to a decreasing trend in larger streams. Our results show that identifying the location of this "breakpoint" is critical for producing optimal ELF model fit. We found that richness breakpoints can be estimated using automated low-supervision methods, with high-supervision providing negligible improvement in detection accuracy. Model fit (and predictive capability) was found to be superior in smaller hydrologic units. The ELF model ("elfgen" R package available on GitHub: ) can be used to generate ELFs using built-in datasets for the conterminous United States, or applied anywhere else streamflow and biodiversity data inputs are available.

The micro‐indentation test has been regarded as an efficient tool to obtain the elasticity modulus and hardness of the minerals in rock, which is essential for studying the deformation‐crack mechanism of the pore structure. However, researches on microscopic plastic parameters have been rarely conducted. This paper develops a novel method to determine the microscopic initial strength and residual strength of brittle sandstone. A dimensionless analysis on the micro‐indentation curve of rock is conducted to acquire its key influencing factors of the elastoplastic properties, which include the initial cohesive force and the residual cohesive force. Then, small cylindrical rock samples are prepared for micro‐CT scanning and micro‐indentation test by a conical indenter to acquire the microstructure, indentation curve, and the microscale elasticity. The pore scale indentation simulation is conducted using the reconstructed rock models with different strength. The function between the indentation curve and strength is deduced by the parametric finite element method (FEM) study. Based on this function, the microscale initial strength and residual strength of the brittle sandstone are determined. The proposed method is validated by comparing the microscale numerical simulation results of uniaxial compression on the representative volume element (RVE) model of rock with the experimental results. A reasonable deviation is observed compared with the experimental benchmark data for the stress‐strain curves, as well as Young's modulus and uniaxial compression strength, proving the effectiveness of the proposed method.