Bridging load

This is an old trick of perturbation theory equivalent to saying that the shape of a bridge loaded with a car is the shape of the bridge without the car, plus the deformation proportional to the mass of the car, plus the deformation proportional to the square of the mass of the car, etc. This works if the bridge is solid and the car is light (the perturbation is small). 

Highway Bridge Loading. British Standard B.S. 5400 Pt. 2 1978 specifies loads on buried rigid pipes due to vehicles, on the basis of their wheel spacing, axle spacing and tyre contact areas. 

Recently a new term spar has been introduced to describe vertical or near-vertical members that are not self-supporting and must depend on cables for its support however, the spar does function as a tower carrying some bridge loads and forces to the ground. In this chapter, the word spar is used to describe a member that cannot support itself but functions as a tower. 

The towers are subject to many different load cases. The towers, as well as the entire structure, must be analyzed, designed, and checked for the controlhng load case. Chapter 6 of Bridge Engineering Handbook, Second Edition Fundamentals presents a detailed discussion of highway bridge loading. 

The concept of using stainless steel rebars is relatively new. At the present time no design standards or specifications are available however, the Canadian Standards Association expects to have a stainless steel design specification available by the end of 1998 for use in Canada. Since working codes and allowable bridge loadings vary in different political subdivisions, design specifications will have to be developed by each individual political subdivision. 

The final bridging load, Fbrdg, can be calculated by summing all the effects considered above ... 

Figure 3.28 Effect of fibre modulus on bridging load and fibre stresses in oriented fibre (45°) in a 30 GPa modulus matrix (after Katz and Li [61,62]).

A funnel flow bin typically exhibits a first-in/last-out type of flow sequence. If the material has sufficient cohesive strength, it may bridge over the outlet. Also, if the narrow flow channel empties out, a stable rathole may form. This stable rathole decreases the bin s five or usable capacity, causes materials to cake or spoil, and/or enhances segregation problems. Collapsing ratholes may impose loads on the stmcture that it was not designed to withstand. 

Because of the steep pitch required, slides are limited in application. They are most commonly used to bridge the gap between roller-conveyor systems on two floors, because the roller conveyor can take the container off the slide rapidly and ehminate or reduce the chance for collisions. Slides may also be used when containers can be chuted from an upper floor to a manually loaded carrier. The use of several rollers at the feed point is recommended for easy dehveiy to the sloping section. If the drop is short and containers light, a roller cleanout will prevent backup of containers on the slide. The slope of gravity slides is a function of container weight, size, and friction characteristics and should be selected with care to be sure that containers do not move either too swiftly or not at all. Slides usually use flat steel sheet. 

Heat build up Design discharge to avoid bridging, provide reli-due to plugged able instrumentation to detect full receiver (load discharge line. cells or level probe) Check lines to ensure they are clear before startup Monitor and alarm temperature CCPS G-f2 CCPS G-23 CCPS G-29 CCPS G-39... 

Fig. 1.4. Magdalene Bridge built in 1 823 an the site of the ancient Saxon bridge over the Cam. The present cast-iron arches carried, until recently, loads far in excess of those envisaged by the designers. Fortunately, the bridge has now undergone a well-earned restoration.

Reducing the residual ripple from single-phase rectifiers for currents up to about 20 A and voltages of up to about 20 V can be achieved by filter circuits of choke coils and condensers. For greater output and constant residual ripple independent of load, the only possibility is the three-phase bridge circuit. It is always more satisfactory than a filter circuit. 

Fig. 16-8 Impressed current anodes for protecting tube supports of a loading bridge.

Today loading piers are mostly cathodically protected with impressed current. At moorings for tankers, cathodic protection rectifiers are installed on extinguisher bridges as far as possible from the hazardous area. Otherwise, they must be of an explosion-proof type. 

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