Practice Periodical on Structural Design and Construction

Given the increasingly competitive environment in the construction industry, investigating the bidding strategies and the influential factors on bidding decisions has become a topic of research since the mid-1950s. To date, numerous decision-making tools have been developed to assist contractors in making bid/no-bid decisions. Despite the excessive availability of the decision-making tools, their utilization rate is very low. Therefore, a practical and user-centered tool to help with the bid/no-bid decisions is needed. The purpose of this study is to develop a practical decision-making tool to assist decision makers in making construction project bidding decisions and selecting the most appropriate projects to bid on using the analytic hierarchy process (AHP). Two illustrative examples, based on hypothetical case studies, are also provided to describe the implementation process of the developed decision-making tool.

The in situ concrete compressive strengths estimated by core tests and nondestructive tests (NDTs) are influenced by various factors, such as level of quality control for concreting operation, carbonation of the concrete surface, and stress history. Most studies of the effect of various factors reported were confined to young concrete (maximum 91 days) cast in the laboratory. The number of studies of the effect of these factors on the in situ compressive strength of aged concrete structures estimated by core tests and nondisruptive tests is limited. It is possible that the effect of some of these factors on the in situ estimated strength identified in studies of young concrete may not be significant for aged concrete structures. The significance of the effect of various factors on the estimated in situ compressive strength of existing aged concrete structures obtained by core tests and nondisruptive tests using 84 sets of the test results of 35 structures aged 4–73 years constructed of concrete with 28-day cube strength of $20–41.5\mathrm{N}/{\mathrm{mm}}^2$ was investigated. The level of quality control of concreting operation of structures constructed during different periods was investigated to identify periods when more structures were constructed with good quality control of concreting operations.

Seismic demand on structures may be estimated using linear response spectrum analysis, linear response history analysis, or nonlinear response history analysis. For response history analysis, a set of ground motion record pairs is required. Requirements for nonlinear analysis in current standards typically include development of a set of at least 11 record pairs scaled to a maximum direction target response spectrum. For site-specific ground motion studies, the current standard also specifies a target logarithmic standard deviation of pseudo-spectral acceleration equal to 0.60 across all periods of significance. The purposes of this study include (1) a demonstration that geometric-mean-based scale factors and maximum-direction-based scale factors for design record suites are similar as long as the engineer is aware of the target spectrum basis, (2) an estimation of log-based variability in inelastic displacements for design suites with a target log-based variability in pseudospectral acceleration, and (3) a brief analysis of the directional combination rule typically used in seismic design. To accomplish these goals, a site near Memphis, Tennessee, in the New Madrid seismic zone was selected. The deep soil deposits characterizing the selected site warrant the consideration of site-specific site factors.

An essential aspect of community disaster recovery planning is understanding the recovery process and developing appropriate probability-based recovery simulation tools to account for interdependent systems of lifeline networks (i.e., water, electrical power, and transportation systems) with the building infrastructure. The objective of this study is to illustrate selection of residential design code changes that are needed to achieve the recovery goals of a virtual community. In the present illustration, the community goals are expressed in terms of functionality of the built environment. This paper focuses only on the electric power network and building clusters subjected to tornado loads. A single combination of design changes selected from three alternatives is demonstrated to achieve the functionality goals at key points in time during the recovery process.

Approximations obtained with the equivalent frame method and the equivalent shear-connection method to assess the elastic average lateral displacement profiles of walls with symmetric and asymmetric openings are compared to results obtained with the finite-element method using reasonably fine meshes. Multistory walls were studied and the contribution of slabs in the lateral stiffness was considered through an equivalent flange, as recommended in several building codes. Different stiffnesses were considered for the walls and the slabs. From the obtained results it is confirmed that approximations obtained with the studied methods increase as the number of stories of the wall increases, and that they are reasonable for an equivalent opening eccentricity parameter up to 40%. Slab stiffness had a reduced impact on the studied walls with openings, but it was important for low-rise walls, impacting more average lateral displacements of walls when they are more flexible and when openings are asymmetric.

Tapered beams are extensively used for structural applications due to their high stiffness-to-mass ratio. They provide many advantages over prismatic beams such as better shear carrying capacity, higher lateral stability, and weight savings. As it is known, axial stress ${\sigma }_x=-My/t$, from Navier’s flexure formula, may be used to estimate bending stresses in tapered beams to some extent, and this can be useful for primary design purposes. However, since the section modulus may vary along the axis of tapered beams, due to the additionally generated shear stress field, the maximum stress cannot necessarily occur at the cross section of the tapered beams where the largest bending moment is present. Nevertheless, classical beam theories do not predict the shear stress distributions in tapered beams if the taper angle is greater than 15°. This study aims at combining the advanced mechanics of a material approach with the theory of elasticity for three different loading conditions applied at the free end of the circular cantilever tapered beams. Derived equations provide the stress distribution across the circular cantilever tapered beams subjected to axial tensile stress, bending moment, and transverse shear force. In order to verify the analytical calculations, a FEM model is employed, and its results shows a reasonable agreement with the analytical results.

Occupational health and safety are the highest priorities in the construction industry. A significant amount of effort has been expended to address and improve site safety. Nevertheless, the rate of injuries and fatalities in construction is high compared to other industries, with falling from heights, falling objects, and tripping hazards the leading causes of fatal and injury accidents in construction. Multiple modern technologies have been implemented on construction sites to monitor worker safety exposures and performance. However, to date, worker locations cannot be accurately identified remotely, especially for those laborers who work on high-rise building projects. Building information modeling (BIM) contains rich building and site information, such as dimensions and elevations, and an indoor positioning system (IPS) inertial measurement unit (IMU) provides a worker’s conditions, including their position, walking speed, and facing direction. Integrating an IPS-IMU system with BIM has great potential for overall construction management and safety control of workers. This paper aims to provide feasible and practical scenarios to use a proposed integrated autowarning system for site safety control. Using data collected from an IPS-IMU and from a three-dimensional site model, the developed system could provide adequate safety notifications and real-time warnings based on safety regulations, guidelines, and policies to prevent site accidents from occurring in an effective and proactive manner. The research also provides an additional approach for further research on innovation and automation development in the construction industry.

There is a recent trend in the construction industry to implement lean concepts. This management strategy is based on a production philosophy originating from the Toyota Production System (TPS) in the 1950s. After World War II, resources were extremely limited, which made it crucial for assembly processes to be as efficient as possible. This led to a focus on minimizing waste and conserving time and the use of physical products. Preassembly, therefore, became a critical phase of the assembly process. In the construction industry, engineers’ primary focus is on incorporating lean strategy for production in shop and field environments; however, opportunities exist to apply the philosophy of the lean concept during the development of design phases. This research proposes that a lean strategy is fully applicable to the design process and the preconstruction phase. A case study is built to illustrate the lean concepts’ applicability, involving the quality assurance and quality control (QAQC) methods of façade design and production. Architects, façade design teams, and consultants implement QAQC processes to ensure the final appearance and performance of the building’s façade meet not only aesthetic expectations but also overall performance criteria.

Practitioners and researchers involved in DOT projects frequently face challenges associated with cost overruns that lead to disagreements between stakeholders and decrease the accuracy of construction cost estimates. To address this issue, this research project identified scoping, cost estimation, and risk assessment practices that are implemented nationwide in the early phases of highway and bridge construction projects. A DOT case study was selected for investigating and assessing the current practices, and interviews were conducted with some of the case study DOT districts’ employees. The results were compared with the practices identified in research documents and effective practices, and a gap analysis was performed. Recommendations were developed, and pilot studies of three projects from the case study districts were conducted to examine the effectiveness of the recommendations. The recommendations were structured in five main areas: cost estimating, documentation, risk assessment and contingency calculations, executive policies, and general issues. The results revealed that most of the recommendations had a considerable impact on the case study DOT’s procedures of scoping, cost estimates, and risk assessments. The findings of this research project will help DOTs mitigate cost overruns by accurately defining the project scope, estimating the costs, and assessing the risks of their projects.