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  1. Free, publicly-accessible full text available October 1, 2023
  2. This research evaluates the impact of switching college engineering courses from in-person instruction to emergency remote learning among engineering students at a university in the Midwest. The study aimed to answer the question: What were the concerns and perceived challenges students faced when traditional in-person engineering courses suddenly transitioned to remote learning? The goal of this study is to uncover the challenges students were facing in engineering online courses and to understand students’ concerns. Our findings can help improve teaching instruction to provide students with previously unavailable educational assistance for online engineering courses. We collected online survey responses during weeks 8 and 9 of the academic semester, shortly after the COVID-19 shutdown and emergency transition to remote learning in Spring 2020. The survey included two open-ended questions which inquired about students’ feedback about moving the class online, and one two-item scale which assessed students’ confidence in online engineering learning. Data analysis for the open-ended questions was guided by the theoretical framework - Social Cognitive Career Theory [1] that explores how context, person factors and social cognitions contribute to career goals, interests and actions. A phenomenological approach [2] was conducted to understand the experience of these students. Open coding and axialmore »coding [2] methods were used to create initial categories then themes related to students' concerns and challenges. Data from the two-item scale was evaluated using descriptive statistics: means, standard deviations, and ranges. Four main themes with separate sub-categories emerged from the student responses: 1) Instructor’s ability to teach course online (Instructional limitations, Seeking help, Increased Workload), 2) Student’s ability to learn online (Time Management, Lower engagement and motivation, Harder to absorb material, Hard to focus, Worry about performance), 3) Difficulties outside of class (Technology issues), and 4) No concerns. Students seemed more concerned about their ability to learn the material (48% of responses) than the instructor’s ability to teach the material (36% of responses). The instructional limitations or lack of instructional support (22% of responses) and time management (12% of responses) were among the major concerns in the sub-categories. The results from two-item scale indicated participants' s confidence in their ability to master their classroom knowledge was at an intermediate level via online instruction (6/10), and participants' confidence in the instructor's ability to teach knowledge in online classes is moderate to high (7/10). The results align with the open-ended question response in which students were somewhat more concerned about their ability to learn than the instructor’s ability to teach. The themes and analysis will be a valuable tool to help institutions and instructors improve student learning experiences.« less
    Free, publicly-accessible full text available June 26, 2023
  3. High levels of sustained load can lead to time-dependent failure of reinforced concrete (RC) members. This in turn may lead to collapse of all or part of a building. Design errors, construction errors, and material deterioration may lead to concrete elements being subjected to high levels of sustained loads well exceeding typical service loads. Plain concrete can experience compressive failure when subjected to a high sustained stress (over 75% of its short-term strength). However, there is a lack of knowledge about the time-dependent strength and stiffness characteristics of RC members under high sustained loads. This paper presents the results of experimental testing of simply supported shear-controlled RC beams under high sustained loads. Two series of beams, consisting of 4 and 5 beams, were tested at concrete ages of 67 to 543 days to represent in-service concrete structures. The applied sustained loads ranged from 82% to 98% of the short-term capacity and lasted for 24 to 52 days. Test results indicated that high sustained load may eventually lead to failure (collapse); however, the level of load needs to be very close (~98%) to the short-term capacity. Under sustained load, all specimens experienced increased deflection with over half of the deflection increasemore »occurring in the first 24 h. The sustained load increased the deflection at shear failure by 190% on average. The increase in the beam deflection may allow for load redistribution in redundant structural systems. A sharp increase in deflection due to tertiary creep occurred in a short time (~2 min) before failure, indicating little warning of the impending failure.« less
    Free, publicly-accessible full text available April 1, 2023
  4. The outbreak of COVID-19 and sudden transition to remote learning brought many changes and challenges to higher education campuses across the nation. This paper evaluates the impact of the transition to remote learning on the engineering-related social cognitions of self-efficacy (belief in one’s abilities to successfully accomplish tasks in engineering) and outcome expectations (beliefs about the consequences of performing engineering behaviors). These social cognitions can be attributed to important academic and career outcomes, such as the development of STEM interests and goals (Lent et al., 2019) and may be especially important in the success of women in non-traditional fields such as engineering. As an extension to a NSF RIEF (Research Initiation in Engineering Formation) study evaluating engineering social cognitions, students in 8 engineering classes were surveyed at the beginning of Spring 2020 semester (N=224), shortly after the transition to remote learning (N = 190), and at the end of the semester (N=101). The classes surveyed included a common early engineering class at the sophomore level (Engineering Statics) and required junior level courses in different departments. The students were surveyed using reliable and validated instruments to measure engineering self-efficacy (Lent et al. 2005, Frantz et al. 2011), engineering outcome expectations (Lentmore »et al. 2003, Lee et al. 2018), and engineering persistence intentions (Lent et al. 2003). The results show a gradual increase in the mean scores on the engineering self-efficacy and outcome expectation measures through the semester. Two tailed t-tests of matched participants showed no significance when comparing the data between the beginning and mid-semester surveys, as well as the mid-semester and end surveys. However, significance was found in the two engineering self-efficacy measures between the beginning and end of semester surveys. Results are compared across courses at different levels and across gender. Results indicate that despite the sudden change in instructional mode, students’ perceptions of engineering self-efficacy and outcome expectations showed a slight increase or no change.« less
  5. Design and construction errors and material deterioration can lead to concrete elements being subjected to high levels of sustained stress well exceeding typical service levels. These high levels of sustained stress have led to structural collapses in the United States and around the world. However, the performance of shear-controlled concrete elements (beams and slab-column connections) under high sustained stress is not well understood. Under high sustained compressive stress (greater than 0.75fc’) concrete will suffer tertiary creep characterized by accelerated permanent strain, leading eventually to a failure. The bond of the reinforcing bars to the concrete is also affected leading to slip. This research presents the results of experimental tests on shear-controlled RC beams that were loaded to 81, 86, and 92 percent of their short-term capacity and observed for about four weeks. Deflection and strain measurements were recorded for each specimen throughout the sustained load test. Under high sustained stress the specimens showed continued deflection with time, with most of the deflection occurring shortly after the application of load. The failure of the specimens exhibited more flexural response than that of the control specimen. The test results show that high levels of sustained stress (up to 92% of their short-termmore »capacity) can be sustained for a prolonged time; however, the deflections and cracking are increased and the ultimate failure mode may be changed. This information will help engineers identify elements nearing failure under high levels of sustained stress.« less