Support system design Traditional steel sheet piles
cofferdam and support is wood or steel, the choice of what material is based on the load to determine. In the past 10 to 15 years, with the popularity of professional equipment and the reduction of wood, has little Use of wood support, in fact, all the support is now steel. The calculation conditions for the load on the purlin are the same as those for those steel sheet piles.
Most small and medium-sized steel sheet piles cofferdams are used for relatively short periods of time. If the owners themselves do not have support materials, it is more economical to use leasing support and preferably by the supplier. The hydraulic cylinders may be prestressed against The manual, the maximum load of up to 2500n, purlin span of 20m Note that, if the steel pile around the purlin span is too large , We must check the amount of deflection, because too much deflection will make the wall and wall Significant ground movement.
For large steel sheet piles cofferdams that exceed the support range, beams, columns, and round tubes are required as support systems, which require stiffening ribs to prevent local buckling. The strength information of the common steel sheet piles support and purlin is given. Data in the table are based on the ultimate load in B5950.
The traditional steel supports can be calculated by using the allowable stress method to calculate the limit state of normal use or the limit state of load carrying capacity in the calculation of sheet pile. In addition, there is an approximate limit design method.
The layout of the support will have a significant impact on the cofferdam installation and removal. The purlin should be set at a certain interval to support brackets on the sheet pile or directly from the nail pendants. Support should be provided with a spreader that can be Used to support the weight of the sheet pile when it is aligned and positioned. Design support must take into account material and mechanical accidental impact, table 54 and table 55 of the data has been considered in the middle to bear] on the impact force. Designers should be based on the scene to ensure that the value of the machine used for large enough to synthesize a variety of information, this value range of about 10 ~ 50m. When the purlin is not placed directly on the cold-formed Z-shaped Sheet pile, it is necessary to use a backing plate, which can be wood (hardwood or hardwood) or concrete-filled bag or steel sheet, depending on the load transmitted.