Practice Periodical on Structural Design and Construction

Considering soil–structure interaction in structural modeling often plays an important role in the seismic design or retrofitting of buildings. In the present paper, soil–structure inertial interaction is analyzed with reference to a single-story precast frame concrete structure (typical of industrial buildings) founded on isolated footings. The analysis was carried out within the framework of a dynamic impedance method. Emphasis was placed on the application of such a method, originally conceived for the case of harmonic vibration in machine massive foundations, in seismic loading. The effects of considering the deformability of foundation soil in the seismic performances of the building are discussed. The adopted method sheds light on the potentialities of applying routine analyses to a great number of similar existing structures that need to be reinforced because they are located in regions of high seismic hazard.

Bridge design spectra in the current design specifications are geometric mean based. In other words, the underlying research on which ground motion data are based predicts the geometric mean spectral acceleration of two horizontal components. This is, perhaps, transparent to many engineers performing bridge design in regions subject to extreme seismic loading. For response spectrum analyses, this does prove problematic when estimating structural response to bidirectional ground motions. Prevailing combination rules rely on the assumption that, when one component produces the maximum structural response, the second component produces 30% of the corresponding maximum. The purpose of this paper is to assess the validity of this prevalent rule for sites characterized by large magnitude earthquakes (M_W = ±7.7) and Site Class D/E subsurface conditions. This study further provides estimates of maximum-to-geometric mean displacement ratios for various levels of ductility and provides estimates of dispersion for inelastic displacements.

This paper presents a design methodology for constructing Tainter gate models using finite-element software. Each step of the model’s construction is given a detailed description and is supplemented with multiple illustrations that show good modeling techniques and pitfalls to avoid. Recommendations on how to attach various structural elements to each other, what boundary conditions to use, and verifying the accuracy of the model through hand methods have been provided.

In past years, many electrical transmission lines have failed during downbursts. This study is part of a research program aimed at understanding the behavior of transmission lines under localized winds. Most downbursts need to be modeled using computational fluid dynamic (CFD) models; this is not an easy task for engineers in general. This paper focuses on replacing the complicated velocities obtained from CFD models with simplified loads that represent, in a more practical fashion, the critical downburst configurations causing the guyed transmission towers to fail. Different options are considered in terms of the location and nature of the design velocity associated with different configurations. The profile of the horizontal velocity is developed. A practical simplified load corresponding to each of the critical configurations is developed. Detailed steps of the conductors’ reaction calculations are provided. A simplified procedure is developed for designing downburst-loaded guyed transmission towers.

Since 1999, self-anchored suspension bridges (SASBs) have undergone rapid development in China, resulting in remarkable technical progresses in many aspects. Therefore, it is of great practical significance to summarize and present some experiences and even lessons for the worldwide community of practicing engineers and researchers. To this end, a state-of-the-art review of SASBs in China is presented. Based on the collected data for 62 SASBs (completed or under construction) in China during the years 1999–2015, the characteristics and statistics regarding bridge completion time, site, span arrangement, girder type, pylon type, and main cable arrangement are comprehensively analyzed, and some conclusions are drawn. Some issues regarding the design and construction of typical SASBs are elaborated to depict their overall scenarios in China. Furthermore, five representative SASBs in China are expounded concerning the structural design and construction techniques, and their respective characteristics are highlighted. Finally, several future research directions for SASBs are provided. The experiences and lessons in this study can serve as a useful building block for constructing more excellent and impressive SASBs.

Prismatic members subjected to internal axial loads exist widely in engineering applications. Because the effects of internal loads and end loads on stability are quite different, the traditional effective length method is not applicable. Engineers require an efficient and convenient method for solving the stability problem of such members. A two-bar model is proposed to illustrate the concept that the effect of compressive axial loads on the stability of sway-inhibited columns can be understood as a negative lateral stiffness. After obtaining the expression of negative lateral stiffness, a relationship between end loads and internal loads can be established so that the internal loads can be considered equivalent to end loads. Then, the column subjected to internal loads can be analyzed as a normal column (without internal axial loads), and the critical buckling load can be obtained easily with the Euler formula. Eigenvalue buckling analyses were performed to examine the proposed method, and the comparison results indicate it has high accuracy.

Mobile equipment operators in surface and underground mines are protected against falling objects by a canopy over the operator’s seat. Designing a structurally safe canopy poses challenges to the design engineer because of a number of assumptions that have to be made in establishing rational design criteria. This paper investigates the design and analysis of falling object protective structures (FOPSs) by proposing a method of energy balance between falling objects and a structure. Elastic and inelastic responses of the structure are considered. The structure is assumed to be supported on springs, simulating the elasticity of the equipment chassis and rubber tires. This realistic assumption results in significant reductions of the impact force on the canopy and supports. It is concluded that these canopies should be designed with column supports that incorporate springs. The design methodology is illustrated by solving a numerical example.

In the integrated design environments of architecture-led projects, structural engineers need to be collaborative team members, and the team needs to be inclusive to structural engineers. However, structural engineers’ participation in integration design has not been fully studied or understood. To add to this knowledge, the experience of 46 practicing engineers was collected and analyzed to conclude that an integrated design environment allows for better engagement by the structural engineer, is more rewarding to the individual, leads to better structural design, and benefits the profession of structural engineering. There are challenges for structural engineers in the relationship with their architectural client, which include architects’ lack of respect for their structural engineering colleagues as well as negative connotations of the field. Positive design environments are described as open with mutual trust so that ideas can be exchanged freely at all points in a project. Although further research is necessary, structural engineers can benefit personally and professionally by participating in the larger discussions of integrated design within the architectural, engineering, and construction communities.