弧门主框架及启闭机系统结构布置的多工况多目标优化

摘要

针对弧门主框架结构布置(主梁悬臂长度、主框架单位刚度比、弧门半径)及启闭机布置时,考虑工况单一、优化目标单一及以经验为主而无法实现全局最优的问题,依据现行水工闸门规范,采用多工况多目标整体优化的方法对闸门和启闭机系统结构布置进行整体优化,优化目标为:1)主横梁跨中正弯矩与支座处负弯矩的绝对值相等,并且在正常蓄水位闸门全闭工况、校核水位瞬间开启工况和闸门全部开启3种工况下的最大值达到最小;2)弧门半径达到最小,且不同工况下支臂端处负弯矩绝对值的最大值达到最小;3)液压启闭机的容量最小.根据规范确定以下约束条件:1)主横梁的悬臂长度;2)主框架单位刚度比;3)液压启闭机在弧门启闭全过程中的正常运行条件;4)弧门半径与门高比;5)液压启闭机启门力的允许范围;6)液压启闭机布置构造要求.据此建立求解弧门主框架和启闭机系统结构布置的多工况多目标整体优化模型.工程实例求得弧门主框架及启闭机系统结构布置最优时的优化变量为:无量纲主梁悬臂长度为0.160,主框架单位刚度比为8.69,弧门半径与门高比为1.3,启闭机吊点位置距闸墩侧墙无量纲距离为0.13,全闭时启闭机的拉杆与支臂的夹角为34.6°.研究结果表明:采用多工况多目标整体优化的方法对弧门和启闭机系统结构布置进行整体优化,不仅方法简洁实用,而且使弧门结构控制内力及启闭机容量均大幅减小,实现了该系统安全性与经济性统一的全局最优布置,同时弥补了中美两国现行规范及现有研究成果中不能考虑不同工况且主梁悬臂长度、主框架单位刚度比、弧门半径以及液压启闭机布置均凭经验选取的不足,又为中美规范的进一步修订完善提供了简明方法.%The single working condition and objective optimizationis often based on experience and thus global optimal solution cannot be reached for the structure layout of main frame of tainter gate (cantilever length of main girder,unit stiffness ratio of main frame,and radius of tainter gate) and hydraulic hoist.Global layout optimization of tainter gate and hoist system under multi-conditions and objectives is carried out based on the current design code for steel gate in water resources and hydropower projects of China and the design of hydraulic steel structures and the design of spillway tainter gates of America.The optimization objectives are:1) The positive bending moment in the middle of the girder is equal to the absolute value of negative moment of the support,and the maximum value reaches the minimum in the conditions of normal water level of the full closeure,check flood water level of instant open and full open;2) The radius of the tainter gate reached is the minimum,and the maximum value of absolute value of negative moment of the strut tends to minimum in the conditions;3) The capacity of hydraulic hoist tends to minimum in the conditions.The constraints are determined to be:1) Range of cantilever length of main girder;2) Range of unit stiffness ratio of main frame;3) Operation conditions of hydraulic hoist in the opening and closing processes of tainter gate;4) Range of the ratio between the radius and height;5) Allowable range of opening force of hydraulic hoist;6) Layout requirements of hydraulic hoist.Global layout optimization of tainter gate and hoist system under multi-conditions and objectives is built based on the above conditions.The optimal structures of the main frame and hoist are obtained by solving the engineering example:the non-dimensional cantilever length was 0.160,and the non-dimensional unit stiffness ratio of girder and strut was 8.69,the non-dimensional ratio between the radius and height was 1.3,and the non-dimensional lifting point position between the side wall of pier was 0.13,and the angle between the pull rod and the strut was 34.6° when the gate was full closed.The results showed that the method of global layout optimization of tainter gate and hoist system under multi-conditions and objectives was simple and practical.Moreover,the internal force of the tainter gate and the capacity of the hoist were greatly reduced and achieves the unity of security and economy of the global optimization layout of tainter gate and hoist.It also makes up for the deficiencies that cannot consider different working conditions,and the randomarrangement of the cantilever length of main girder,unit stiffness ratio of main frame,radius and hydraulic hoist by experience,and also provides the simple method of the global optimal arrangement for the revision of the codes of China and America.