Frances Appleton Pedestrian Bridge Design and Construction

<p>The Frances Appleton Pedestrian Bridge is an innovative steel arch bridge with a 69m main span and curvilinear approaches along the Charles River in Boston, Massachusetts. It is the first Americans with Disabilities Act fully accessible 4.3m wide bridge connecting Boston’s historic Beacon Hill neighborhood to the Esplanade Park and Charles River. An overall architectural and structural theme was followed in the design of all bridge components including the main arch, Y shaped approach piers, circular stairs and curved ramps. The bridge is light, elegant and well-integrated into the landscape complementing an adjacent historic landmark bridge and seamlessly blending into the waterfront context.</p>

Vertical Gradient Temperature Difference of the Main Arch with Single Pipe Section in Tibet Based on Statistical Analysis

A 75 m long experimental arch with a 1.6 m diameter was constructed in Tibet for a one-year test to determine the most unfavourable vertical temperature difference for a single pipe in the main arch of a concrete-filled steel tube arch bridge. Actual temperature observation data were used to analyse the vertical temperature difference in the single circular pipe arch rib using statistical methods. The standard value for the vertical temperature difference in the single pipe under a return period of 50 years was calculated. The results showed that the influence range of the vertical gradient temperature was 25 cm. The vertical temperature difference followed a lognormal distribution, and the standard values of the positive temperature difference at the upper and lower ends of the single pipe were 16 and 10°C, respectively; the standard values of the negative temperature difference at the upper and lower ends of the single pipe were both -8°C under a return period of 50 years. These results are considerably different from the values specified in the current Chinese code. These could serve as references for calculations involving arch bridges in Tibet with single circular pipes in the main arches.

Traditional use of Dasylirion acrotrichum in the Construction of Floral Arches for the Festival of San Jerónimo, in Coatepec, Veracruz, Mexico

In Mexico, floral arches are commonly constructed as offerings in religious festivals. The plants required for fabrication of these arches are currently in great demand, which could affect the species involved. The objective of this study was to document the traditional management of Dasylirion acrotrichum (cucharilla) as used in the construction of floral arches during a festival of great religious and community significance held every year in Coatepec, Veracruz, Mexico. The construction method of floral arches was documented, and the possible repercussions of this practice on the wild populations of this species were analyzed. In Coatepec, the mayordomía is a non-rotational traditional organization system, through which each arch is produced. This system guides the construction activities of the floral arch, which are shared among different actors with various degrees of experience and responsibility. We reveal that between 250 to 270 plants (ultimately using around 60% of this number) are used to produce the main arch. Likewise, it was documented that during plant collection there are rules observed to avoid extraction of juvenile specimens, especially those that do not have the quantity or quality of leaves required. The social, ritual, and ecological basis of the mayordomía represent an opportunity to build a strategy aimed at regulating the extraction of culturally relevant plant species, and it can also help to improve collection techniques and to encourage sustainable management. That is why we argue that Dasylirion acrotrichum must be understood and studied from a systemic, interdisciplinary perspective.

Deflection distribution estimation of the main arch of arch bridges based on long-gauge fiber optic sensing technology

Deflection of the main arch of arch bridges is one of the main indices for supporting the alignment after construction and evaluating the structural performance. The existing sensing technology and analysis method for deflection monitoring have developed, but it is still difficult to monitor the deflection of the main arch of a long-span arch bridge with great height difference between measuring points. On the contrary, in recent years, with the outstanding advantages of fiber optic sensing technologies, a long-gauge fiber Bragg grating sensing technology has been used in structural health monitoring due to its characteristics, including reflecting the macro and micro information and being connected into network. For these reasons, the long-gauge fiber Bragg grating sensing technology is proposed to develop a method to monitor the deflection of the main arch of arch bridges. A curvature load method for deflection distribution estimation using strain measurements is proposed. It deduces the expression of the complex relation between the strain and the deformation on the main arch element and then separates the coupled strain on the element through the specific sensor layout. A series of simulation tests of the deck arch bridge, half-through bridge, and through arch bridge was conducted. It is concluded that the proposed method can not only be applied to these long-span arch bridges but also can identify the static and dynamic deflections of the main arch effectively.

Lancang River Railway Arch Bridge with stiffened skeleton of Concrete-filled Steel Tubes

<p>The Lancang River railway arch bridge, a key project, is located on Dali~Ruili Railway with a design speed of 140 km/h. The bridge spans over the Lancang River, with the max slope angle of the mountain body on both sides of the river being more than 80 degrees. The distance between the bridge deck and the river surface exceeds 270 m. The whole bridge is 528.1 m long and the main span is 342 m. The x-style arch rib is a deck-type concrete-filled steel tube stiffened skeleton, which becomes the main arch structure of single-box single-cell box section after swing erection, by means of filling the inner space and covering the outer face with concrete.</p>

Construction Simulation Analysis of 60m-span Concrete Filled Steel Tube arch bridge

The construction process of the CFST arch bridge is complicated. The construction process not only affects the structural stress in the installation, but also determines the form a bridge and internal force of the bridge. In this paper, a 60m span concrete filled steel tube tied arch bridge is taken as the background, and a three-dimensional finite element simulation model is established by using the MIDAS/Civil bridge structure analysis software. The elevation of the main arch ring, the beam stress, the forces in hanger rods and the modal frequency of the main arch during the construction stage are calculated, and the construction process is simulated and analyzed. Effectively and reasonably guide the construction and ensure that the line and force conditions of the completed bridge meet the design requirements and provides a reliable technical guarantee for the safe construction of the bridge.

A custom made grid to guide placement of temporary anchorage devices

The use of implant anchorage has simplified orthodontic treatment by sparing us the need for patient compliance and the complexity of treatment. One of the most important factors affecting the success of interdental implants is preventing the damage to adjacent roots and periodontal ligament. The most common causes of root damage from mini-implant insertion are improper site selection and an inaccurate angle of drill penetration. We thereby present a custom made modified grid help in more accurate placement of temporary anchorage devices and guide the angle of drill penetration. The grid can be placed anywhere in the oral cavity (buccally, palatally, anteriorly or posteriorly) and it can be attached to the main arch wire, bracket or even on unbounded teeth. The measuring reference grid with two vertical guide arms is connected with a horizontal arm that will later be secured to the adjacent bracket at both ends. The grid includes small squares, which effectively upgrade the efficiency during the orthodontic implant placement. The two vertical guide arms help in maintaining the desired angulation while drilling indicating the mesial and distal root surface of the adjacent teeth.