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Many previous studies have been conducted to investigate wind-induced galloping of slender structures or structural members. While some recent studies have examined the particular problem of galloping involving coupling between vibration components about the principal axes, few occurrences of such vibrations of full-scale structures have been reported. This paper presents a comprehensive investigation that incorporates full-scale and wind tunnel experiments and an analytical formulation to study the galloping oscillation of a type of slender tower. The full-scale and wind tunnel experiments were conducted to assess the characteristics of the oscillations, their correlation with the wind characteristics, as well as the core parameters that influence the interaction between the tower and the wind. Based on the results from the experiments, a state-space model for coupled galloping of slender towers is formulated. This model enables the prediction of the susceptibility of a slender tower to galloping instability through an evaluation of the net damping resulting from the wind-structure interaction. The tower subjected to monitoring in the full-scale study is used as an example structure in an illustrative application of the analytical model.

Laminated glass consists of at least two monolithic glass lites bonded together by an elastomeric interlayer. Existing mathematical models using the finite-difference method or the nine-nod...

The authors tested five full scale samples of nominal 6 mm thick heat strengthened glass to failure under uniform lateral loading. One sample was clear glass, one sample had full coverage ceramic enamel frit, and the other three samples had ceramic enamel frit patterns with different percentages of coverage. In testing the samples with ceramic enamel frit applications, researchers oriented the specimens to place the ceramic enamel frit in tension under lateral loading. The authors found that the samples with ceramic enamel frit displayed considerably lower magnitudes of load resistance than did the clear heat strengthened sample. In addition, the authors noted that every fracture origin they have inspected to date from the 75 specimens with ceramic enamel frit patterns occurred underneath frit. Micrographs of fracture origins indicate that the frit may actually damage the glass surface during the heat strengthening process. This study has significant implications for architectural glass design.

In the past few decades, designers increasingly work on glazing projects across the world requiring the use of international glazing standards that often differ from the designer’s national code. Commonly specified international glazing standards include prEN16612, AS1288, and ASTM E1300. Each of these standards has a different approach to determine window glass strength. This paper explores one aspect of glazing design for insulating glass units, the method for estimating the load sharing between the lites comprising insulating glass units. Each glazing standard uses a different method for estimating load sharing and how the effects of environmental loads are incorporated into the estimation. Environmental loads include but are not limited to changes in atmospheric pressure, resulting from elevation, climatic, and temperature variations. Additionally, several iterative methods appear in technical literature that attempt to account for most known factors affecting insulating glass load sharing. Each of these methods addresses environmental loads differently with differing degrees of accuracy. This paper presents comparisons between the three glazing standards above and an iterative method for load sharing with environmental loads in double and triple glazed insulating glass units. The major factors varied in the investigation are insulating glass unit constructions, dimensions, glass lite thicknesses, air space thickness, temperature and pressure and atmospheric pressure changes due to elevation change. Pressure versus load sharing percentage curves are presented for select double and triple insulating glass unit constructions. Figures in this paper will show the load sharing trends of different similarly loaded insulating glass units due to varying the pressure differential between the air space(s) and atmospheric pressures. The results of this study will indicate differences between the load sharing methods and provide example scenarios where the methods produce similar and different estimates of insulating glass load sharing.

In the published article, Table 8 is incorrect (the last value in column 2 and all numbers in column 3). The correct table is given below

Understanding fracture initiation and propagation from perforated wellbores is essential to designing a perforation scheme to achieve an efficient hydraulic fracture stimulation treatment. The effect of perforation design on hydraulic fracture propagation has been extensively studied using experimental and analytical methods. Because the experimental investigation of hydraulic fracture is complicated, expensive, and often returns limited results, numerical methods can be applied as an efficient way to simulate fracture propagation from perforations. An Extended Finite Element Method (XFEM) was used to develop a model to investigate the effects of various parameters on fracture propagation from a set of perforations. These parameters included perforation orientation, perforation length, stress anisotropy, and elastic properties of the formation. Fracture propagation patterns from the XFEM model were first matched against published experimental studies and exhibited good agreement. The model was then used to broaden the study of perforation effects. Results of the modeling proved the effects of perforation orientation and length on hydraulic fracture propagation pattern. Horizontal stress anisotropy and rock mechanical properties were observed to strongly influence fracture propagation. It was also observed that, when two or more perforations are positioned at different orientation angles at the same depth, a fracture tends to propagate from the less deviated perforation. In these cases, the more deviated perforation can develop a short fracture, following a propagating pattern that could be caused by stress shadowing/interference. Stress interference between two perforations positioned closely together results in either perforation breakdown or fracture propagating away from one another. The simulation results from this study offer methods to enhance perforation design for hydraulic fracture treatment, particularly in the case of high stress anisotropy and high uncertainty in a preferred fracture plane. Analyzing competing perforations suggests that a technique based on this concept can be applied when high uncertainty exists regarding the direction of the principal horizontal stresses through increasing perforation density.