Study On Roof Rainwater Drainage System

With the development of the national economy and society in recent years, building′s roofs differ in thousands of ways and become rich and colorful, there are various big area roof exhibition hall and modern industrial workshop being constructed in each place, these constructions are grandiose and artistic practical generally, but has also brought the problems in design of big area roof rainwater drainage system along with it. Design of roof rainwater drainage system in our country according to gravitational fluid formerly, but gravitational rainwater drainage system is limited by its hydraulic characteristic, already could not meet the demands of these projects. Newly emerging siphonic roof rainwater drainage system has been developed in Europe. This paper demonstrates advantages of siphonic roof rainwater drainage system for dium- and large-scale roofs by comparison on gravitational rainwater drainage system and siphonic rainwater drainage system in technical and economical aspects.As a new-style rainwater drainage system, siphonic roof rainwater drainage system has some disputable issues such as hydraulic operating mode, recurrence period of design and suitable calculation formulae, so this paper will discuss these issues. One of the keys of siphonic rainwater drainage system is hydraulics calculation′s accuracy, the goal of hydraulics calculation is taking full advantage of hydraulic head that system offers, minishing pipe′s diameter, reducing costs and ensuring system working safely, reliably and normally. This paper exposits the work principle and hydraulics calculation method of siphonic roof rainwater drainage system, and uses the C++ language to establish the calculator procedure, which makes hydraulics calculation of siphonic rainwater drainage system realize automation, allays the workload greatly, improves hydraulics calculation′s accuracy and makes the system work more stablely.Siphonic rainwater drainage system is a new-style rainwater drainage system, it is very significant to design rainwater pipes economically and rationally, which makes the system have optimal capability of drainage, drain furthest in time but not cause the construction scale to surpass the actual demand. When carries on optimal calculation of the rainwater pipeline, the final optimization computed result is resolved through seeking the costs to be lowest, namely final decision-making and expense function are closely related. This paper studies the curve-fitting of the unit length of pipe cost Cg, i, and extracts objective function accordingly that optimizes the rainwater pipeline. But, in optimal design, we must according to the actual demand and give some restrictions on design parameter, which is expressed as inequality constraint function or equality constraint function of design variable. In order to adapt non-linear characteristic of objective function and the constraint condition, this paper has established the nonlinear programming model. Then, this paper establish accessorial function by penalty function method to turn constraint problem into nonrestraint problem, obtain optimal pipe′s diameter combination accordingly.