Social Presence, Satisfaction, and Learning Outcomes in an Undergraduate Computer Programming Distance Course

This study investigated the social presence, satisfaction and learning outcomes of undergraduate students based on their participation in an emergency remote online course entitled “Educational Programming Environments” during the COVID-19 pandemic. Instruction was delivered using a student-centered design and discovery learning to teach computer programming problem solving. Data were collected from 39 students who did not undertake prior preparation for engaging in distance education. Social presence, learning outcomes and satisfaction towards the course were measured by previous well-established scales, respectively. The students’ learning outcomes were evaluated through their code development. At the end of the course, the students filled out an online questionnaire which measured these three variables. The results of this study showed that all three variables were evaluated as satisfactory by the students. The results also indicated that social presence and code development were positively associated with satisfaction. Moreover, the results of the regression analysis indicated that social presence and code development were critical factors affecting students’ satisfaction. Together, these two factors explain 39.9% of the variance of satisfaction. Social presence alone contributed about 32.3% of this variance, suggesting that it may be very important in predicting satisfaction. This study could prove useful to instructors in understanding which factors may influence the design and implementation of distance learning in higher education. © 2021, Springer Nature Switzerland AG

Elastoplastic Dilatant Interface Model for Cyclic Bond-Slip Behavior of Reinforcing Bars

Publisher Copyright: © 2015 American Society of Civil Engineers.This paper presents a new interface model to simulate the cyclic bond-slip behavior of steel reinforcing bars embedded inconcrete. A multi-surface plasticity formulation is used to model two major inelastic deformation mechanisms occurring in bond slip.One is the crushing and shearing of the concrete between the bar ribs, and the other is the sliding between the concrete and bar surfaces.These two mechanisms are represented by different yield surfaces and nonassociated flow rules. The flow rules account for the sheardilatation of the interface induced by the wedging action of the bar ribs and crushed concrete particles. The interface model has been implementedin a finite element analysis program and has been validated with experimental data. The model is easy to calibrate and is able toreproduce the bond-slip behavior of bars under a wide range of confinement situations, including bar pullout and concrete splitting failures.Peer reviewe

Nonlinear Beam-Truss Model (BTM) for seismic performance evaluation of reinforced concrete wall buildings

This paper presents an accurate, simple and computationally efficient method called the beam-truss model (BTM), for the computational seismic performance assessment and design of reinforced concrete (RC) structural wall buildings. The BTM has been extensively validated through a number of prior studies, and its capability to enable the accurate simulation of planar and flanged walls, coupled walls and entire building systems, has been demonstrated. A recent implementation of the BTM as a four-node shell macroelement substantially facilitates the definition and post-processing of analysis. The method is currently used for transforming the modeling and seismic performance evaluation of existing RC walls, enabling the formulation and use of performance acceptance criteria based on local material damage states. Furthermore, the BTM enables the fully nonlinear static and dynamic analysis of entire buildings including three-dimensional ground motions improving substantially the predicting capabilities of nonlinear analysis practice for performance-based seismic design (PBSD) and assessment.Postprint (published version

Evaluation of infilled frames: an updated in-plane-stiffness macro-model considering the effects of vertical loads

The influence of masonry infills on the in-plane behaviour of RC framed structures is a central topic in the seismic evaluation and retrofitting of existing buildings. Many models in the literature use an equivalent strut member in order to represent the infill but, among the parameters influencing the equivalent strut behaviour, the effect of vertical loads acting on the frames is recognized but not quantified. Nevertheless a vertical load causes a non-negligible variation in the in-plane behaviour of infilled frames by influencing the effective volume of the infill. This results in a change in the stiffness and strength of the system. This paper presents an equivalent diagonal pin-jointed strut model taking into account the stiffening effect of vertical loads on the infill in the initial state. The in-plane stiffness of a range of infilled frames was evaluated using a finite element model of the frame-infill system and the cross-section of the strut equivalent to the infill was obtained for different levels of vertical loading by imposing the equivalence between the frame containing the infill and the frame containing the diagonal strut. In this way a law for identifying the equivalent strut width depending on the geometrical and mechanical characteristics of the infilled frame was generalized to consider the influence of vertical loads for use in the practical applications. The strategy presented, limited to the initial stiffness of infilled frames, is preparatory to the definition of complete non-linear cyclic laws for the equivalent strut