Practice Periodical on Structural Design and Construction

Two laws of structural mechanics are presented in this paper. (1) If an entire structure consists of a main part and a statically determinate subsidiary part, then the load applied on the subsidiary part always produces internal forces in the main part, but the load applied on the main part generates no internal force in the subsidiary part. (2) If an entire structure consists of a main part and a subsidiary part with statically determinate horizontal forces, then the load applied on the main part produces no horizontal internal force in the subsidiary part. These laws can be applied to the seismic design of buildings. If the stairs are the statically determinate subsidiary part of an entire building structure, then internal forces in the stair structure are always small, because no large loads are applied on the stairs. In this case the stairs do not fail. If the stair structure corresponds to the subsidiary part, in which horizontal forces are statically determinate, then horizontal internal forces in the stair structure are always small. Hence, adopting statically determinate stairs or stairs with statically determinate horizontal forces is a critical measure for preventing stair failure.

This article presents a multihazard-resistant panelized brick veneer with steel stud backup (PBVSS) system capable of being developed off-site with fiber-reinforced polymer (FRP) enhancements. This study is a continuation of two previous studies of PBVSS systems developed at Pennsylvania State University in the Building Components and Envelopes Research Laboratory (BCERL). The specimens used in this study include one control specimen. Two types of composites were used, glass fiber-reinforced polymer (GFRP) and spray polyurea, with three composite configurations. Experimental data obtained from a uniformly applied pressure through an air bladder with expected boundary conditions were collected. The measured test data provided a basis for evaluating the performance and capacity of the PBVSS, particularly the veneer portion. A comparison of specimen test results shows that the FRP enhancements on the interior side of brick veneer provide additional veneer capacity. Beyond the performance of the veneer, the study shows that it is indeed possible to reinforce the interior side of a brick veneer surface if it is constructed in panelized segments in a factory setting.

In this paper, the solitary wave forces on a typical coastal bridge deck are evaluated numerically based on a component level assessment, and the countermeasure of the air venting holes is investigated. At first, a wave model based on the second-order solitary wave theory is presented to represent the incident waves in tsunami events. The shear stress transport (SST) k-ω model is used as the turbulence closure for the Reynolds-averaged Navier-Stokes (RANS) equations. Then, the characteristics of the wave forces (the horizontal force, the vertical force, and the moment) considering three different still-water levels (SWLs) and four wave heights for each SWL are investigated, and the effects of the SWLs and wave heights are demonstrated. In addition, a component level–based assessment of the wave loadings, especially the overturning moment, varying along the wave propagation is conducted to enhance the understanding of the force distribution on the bridge deck. Finally, the countermeasure of the air venting holes with different venting ratios is studied. It is proven that this countermeasure is beneficial in reducing the positive vertical (uplift) force dramatically, but it results in a corresponding increase of the horizontal force. It is hoped that this study will facilitate practicing engineers with an in-depth understanding of the wave force variation in the bridge deck–wave interaction process and shed light on the consideration of adopting this countermeasure in future engineering practices.

Design of thick plate double-Tee connections is discussed and evaluated based on experimental data and analytical studies. This paper summarizes the results of an extensive experimental and analytical work aiming at widening the applicability of double-Tee connections needed for deep beams that meet the performance requirements for moment-resisting frames (MRFs) in seismic areas as specified in seismic provisions. New limit states controlling the strength and deformation capacities of the connections are presented. A detailed comprehensive design methodology and design examples of thick plate double-Tee connections are developed. The proposed design procedure includes all possible yielding mechanisms and failure modes that might occur in thick plate double-Tee connections and accounts for the maximum rotational capacity demand in the connection, as required for seismic analysis and design. The information presented in this paper can be used toward prequalification of thick plate double-Tee connections for use in MRFs in seismic areas.

The creation of underground space is an integral part of urban infrastructure development because it provides a way to accommodate denser urbanization while maintaining the quality of metropolitan life. To be successful, large-scale underground construction in cities must be performed safely with minimal impact on economic activity. A detailed record of construction activity is needed to complement and correlate with measured excavation response. This paper presents novel imaging and software used in conjunction with traditional documentation methods to capture progress of the Transbay Transit Center (TTC) excavation in downtown San Francisco. A handheld digital camera, high-definition hard-hat-mounted action camera, and unmanned drone-mounted camera were used to acquire excavation geometry during progressive stages of construction. Raw two-dimensional imaging data were converted to three-dimensional construction staging models. A social media platform used as a communication tool among project personnel, generated data that were mined for construction-history information. The virtual models and social media data supplemented with field notes and drawings were used to develop a higher-fidelity digital archive that can be used to efficiently capture and preserve detailed construction history.

This paper presents a preliminary evaluation of the load-bearing capacities of cast-in anchor channels using numerical simulations and destructive tests. Two finite-element models were developed to predict the ultimate failure loads in all three directions (i.e., tensile and shear loads perpendicular to the length of the channel and shear load along the length of the channel). A series of destructive tests was then carried out to verify the accuracy of the developed finite-element models. The experimental results together with the results of the numerical simulations confirmed the importance of applying an appropriate tightening torque when designing the cast-in anchor channel. In addition, the British technical specifications were demonstrated to be conservative for practical applications.