Lightweight Utility Cover Structure for Traffic Load Strength
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Solution Overview
Problem
Underground utility enclosure lids made of polymer concrete are too heavy, making them difficult to remove due to their increased weight, which is necessary for structural integrity to withstand traffic loads.
Innovation Solution
A lightweight cover design for underground enclosures featuring a pattern of bosses on the upper surface, slots for lifting, and a support structure on the lower surface, made from glass fiber reinforced polyester sheet molding compound (SMC) with reinforcement members and ribs, allowing for easier handling and removal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If polymer concrete is used to make the lid, then the structural integrity to withstand traffic loads is improved, but the weight of the lid increases significantly
Solution Approach 1:
The lid is constructed using a composite material system consisting of a polymer concrete base layer providing structural strength, combined with a lighter polymer cap layer. This composite structure allows the lid to withstand traffic loads while reducing overall weight compared to solid polymer concrete construction.
Solution Approach 2:
The lid is divided into multiple functional layers: a polymer concrete base layer for structural support and a separate polymer cap layer for the lifting surface. This segmentation allows each layer to be optimized for its specific function, with the cap layer being lighter and easier to handle.
2Strength
If polymer concrete is used to make the lid, then the structural integrity to withstand traffic loads is improved, but the ease of operation for removal and installation deteriorates
Solution Approach 1:
The lid is segmented into a heavy polymer concrete base layer that remains stationary during operation, and a lighter polymer cap layer that can be easily removed. The slots are formed in the cap layer, allowing lifting equipment to engage with the lighter portion for easy removal while the base layer provides anchoring stability.
Solution Approach 2:
The polymer cap layer acts as an intermediary between the heavy polymer concrete base and the lifting equipment. It provides the slots for lifting attachment while being light enough to be easily manipulated, serving as a mediator that enables easy operation without compromising the structural function of the base layer.
3Ease of operation
If the lid is made lighter, then the ease of operation for removal is improved, but the structural integrity to withstand traffic loads deteriorates
Solution Approach 1:
The lid structure is segmented so that the structural support function is separated from the handling function. The polymer concrete base layer provides the necessary structural integrity for withstanding traffic loads, while the lighter polymer cap layer provides the slots for easy removal and installation operations.
Solution Approach 2:
A composite construction combining polymer concrete and lighter polymer materials allows the lid to achieve both lightweight handling characteristics and sufficient structural strength. The polymer concrete base provides load-bearing capacity while the polymer cap enables easy operation.
Data Source
AI summary
A cover for an underground enclosure may include an upper surface comprising a pattern of bosses, a first slot and a second slot disposed on the upper surface, a lower surface opposite the upper surface. A first reinforcement member may be coupled to the lower surface. The first slot may extend into the first reinforcement member, and a second reinforcement member may be coupled to the lower surface and aligned with the first reinforcement member. The second slot may extend into the second reinforcement member. The cover may be configured to be lifted by the first slot and the second slot.