Assigning labour-hours to a certain scope of work during design and estimating is still more of an art than a science. This research proposes a data-driven approach that uses multiple linear regression (MLR) and available historical data from building information models (BIM) to associate project labour-hours and project design features. The framework relies on an enhanced version of stepwise regression technique to select the most relevant predictive factors and generate a predictive model without compromising the achievable accuracy of regression. The framework also encompasses analytical methods for justifying MLR application, validating the resulting model, and establishing range estimates for point-value predictions. In collaboration with an industry partner, the framework application is exemplified by analyzing labour-hours and design features for structural steel fabrication, leading to the creation of a valid MLR model in the simplest form. Finally, pros and cons for the proposed framework and opportunities for future research are discussed.
The behaviour of partially grouted (PG) masonry shear walls is complex due to masonry’s anisotropic nature and the nonlinear interactions among its constituents. Currently available code- and research-based shear strength equations provide highly variable results when predicting the in-plane shear strength of PG masonry walls. It is crucial to develop a greater understanding in this area, as sudden shear failures of masonry walls can lead to catastrophic losses of human life and property. This study presents the development of several new in-plane shear strength models for PG masonry walls using stepwise regression and model trees with data compiled from 292 experimentally tested walls. The models are found to significantly outperform existing code- and research-based shear strength equations. It was found that, of the variables studied, the most significant ones are the axial load, wall geometry, compressive strength of mortar, and area of interior vertical reinforcement.
The model tree algorithm of M5 is integrated with the multiple linear regression technique called modified stepwise regression (MSR), resulting in a new methodology for modeling complex civil engineering problems. We purposefully chose artificial neural networks (ANN) for comparison against the proposed “M5+MSR” because they fall at the two ends of the model interpretability spectrum in machine learning. In two application cases (case 1: concrete workability and case 2: steel fabrication estimating), the proposed “M5+MSR” gave rise to explainable regression tree models featuring substantially reduced complexities against ANN and model prediction errors comparable to ANN. In both cases, the resulting “M5+MSR” models consistently outperformed ANN in terms of model overfitting metrics by 19% in case 1 and by 21% in case 2, thus boasting better learning performances. The proposed new methodology will potentially find applications in tackling a wide range of complicated engineering problems that entail fitting prediction models based on laboratory or field data.
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