Practice Periodical on Structural Design and Construction

A cantilevered sign support structure failed, which was attributed to fatigue fracture of the anchor bolts. The failed structure was designed before the publication of the AASHTO fatigue provisions. The structure was replaced with a similar arrangement but designed using the AASHTO fatigue provisions. It was equipped with a double-nut-moment joint to concrete foundation using a 31.75-mm (1.25-in.) thick, 889-mm (35-in.) diameter base plate and eight galvanized 38.1-mm (1.5-in.) diameter bent anchor bolts. Significant clearance discrepancies between the base plate and the foundation for each of the anchor bolts existed because of topographical limitations. Experimental evaluation on the fatigue behavior attributable to natural wind was conducted on the anchor bolt attachments for validation of the AASHTO fatigue provisions. The results of the study indicated an irregular distribution of stress ranges between anchor bolts, with a portion having stress ranges greater than the values calculated using the AASHTO standards as well as the constant-amplitude fatigue limit of the anchor bolt connection detail.

Lack of knowledge about the performance of emerging sewer rehabilitation technologies represents a critical shortcoming in the water infrastructure industry. This has led the leading aging water infrastructure research organizations to develop pipe rehabilitation technology demonstration programs. Specific scenarios of interest include technologies applicable to challenging site conditions and pipes with challenging configurations. The results of these programs are intended to enhance the industry’s awareness of available technologies and their capabilities. This paper describes the demonstration of an emerging ultraviolet (UV)-cured, glass fiber–reinforced (GFR) cured-in-place pipe (CIPP) technology used to rehabilitate 271 m (888 ft) of 250-mm (10-in.) clay pipe in Frisco, Texas. This technology met the utility owner’s requirements, and mechanical testing showed that the liner exceeded the minimum design requirements. A key takeaway from this project was the importance of using the proper test method when evaluating the liner’s structural properties. These findings are valuable for water infrastructure system engineers in need of alternatives to traditionally disruptive pipeline renewal methods.

The variations of three residual mechanical parameters in a set of partially prestressed, precast concrete I-beams after being subjected to concentrated high-level cyclic loading are presented and discussed. These three mechanical parameters are flexural stiffness, natural frequency, and crack width. Two precast prestressed I-beams were tested under three-point bending cyclic loads, varying between 60 and 90% of their ultimate moment. This range corresponds to 72 and 108% of cracking moment. Having reached a prefixed number of cycles, the cyclic load testing stopped, and static testing was done up to 90% of the ultimate moment. Variations of the three aforementioned mechanical parameters with the number of cycles were observed, especially the crack width. The main conclusion, in this case, is that cyclic loading caused insignificant variations in beam stiffness and, as a consequence, insignificant variations in the mechanical parameters. On the contrary, significant variations in crack widths were observed.

Construction activities required to renovate or enlarge buildings cause vibration levels that could impede facility functionality. Facility and construction managers should have an understanding of the magnitude and frequencies of construction vibrations and how far their effects travel in a building. Vertical elements such as columns in a building transmit the vibrations into other floors. The pouring and vibrating of concrete columns are expected to create high vibrations and transmit them vertically. This paper investigates the vibrations caused by construction activities, particularly those caused by concrete column pours, during the construction of three RC buildings. The RMS of the velocities at varying frequencies and varying building locations was recorded. The vibration levels were compared with the vibration criteria previously set for human environments. Significant increases in velocities were observed during column pours, especially for low frequencies. For low frequencies, vibrations exceeded the limits for operation rooms and rat vivariums. Velocities did not decrease consistently with increasing distances from the column pour within one structural bay.

Relatively little research has been reported on the time-dependent in-service behavior of composite concrete slabs with profiled steel decking as permanent formwork, and little guidance is available for calculating long-term deflections. The drying-shrinkage profile through the thickness of a composite slab is greatly affected by the impermeable steel deck at the slab soffit, and this has only recently been quantified. Based on an existing analytical model developed by the authors to calculate the time-dependent deflection of composite slabs, a simplified procedure, suitable for use in structural design, is proposed for calculating the time-dependent deflection of composite concrete slabs with steel decking as permanent formwork that takes into account the time-dependent effects of creep and shrinkage. The method is illustrated by three examples and the results are compared with the experimental data.

Wood panelized roof systems are a highly popular system for the construction of large-footprint, low-slope roofs, typically for single-story warehouse or industrial buildings. These panelized systems have been used for decades, commonly in the western United States. In general, large modular sections of the roof assembly are constructed on the ground, then lifted into place and connected to the primary roof support elements, which allows for rapid roof erection. In 2008, a $2\times 6$ by 3.0-m (10-ft)-long wood subpurlin fell from a building’s roof structure and landed on the floor approximately 9.1 m (30 ft) below during roof maintenance work. The building was constructed about 3 years prior to the subpurlin falling incident. The authors investigated the cause of the incident. Installation errors of the subpurlin hanger were found in sufficient quantity that the investigation grew to include a total of 21 similar buildings built by the same contractor, representing more than $\mathrm{370,000}\hspace{0.17em}{\mathrm{m}}^2$ (4 million sq ft) of roof. This paper presents the findings regarding construction defects related to hanger installation. Also presented are the results of a testing program conducted to determine acceptable tolerances for subpurlin hanger defects, with the goal of developing an efficient repair program.

Historic and therefore older adobe buildings, because of the nature of their construction, always suffer severe damage during major earthquakes. This paper describes the rehabilitation of an almost 100-year-old adobe church using welded-steel mesh as a stability retrofit measure. The objectives of the rehabilitation were to create a structure capable of surviving a strong seismic event and to do so without damaging the original dynamics and architectural character of the building. The church has 7.9-m-high lateral adobe walls and a timber-truss roof system. The slenderness ratio of the walls is $\text{∼}10$. Since its rehabilitation, this church has successfully withstood 16 earthquakes with magnitudes from 4.1 to 6.0.

Many construction firms now use building information modeling (BIM), and champions at those firms know that BIM delivers significant benefits. Whether the benefits are significant enough to merit deeper BIM adoption is unclear at this point in the architecture/engineering/construction (A/E/C) industry. To investigate this problem, the lead author conducted more than 51 workshops worldwide with practitioners who presently use BIM and elicited cost and benefit data from them using actual project case study data. The workshops provided a structured approach to capturing the true benefits of BIM in the A/E/C community. Through the workshop case study approach, 19 of the most impactful benefits that accompany an integrated, all-in approach to BIM were identified. This paper describes these benefits in detail, as well as the current limitations, and sheds light on attributes of BIM in the near future. The findings have the potential to help the A/E/C industry make informed decisions to maximize returns on BIM investment and establish realistic success targets and measures.