Polystyrene Interjoist with Steel Z-Section Stiffeners

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Solution Overview

Problem

The existing interjoists made of polystyrene struggle to meet mechanical strength requirements while maintaining a reduced thickness, leading to increased beam height and weight penalties.

Innovation Solution

Incorporating Z-section angle iron stiffeners made of higher resistance materials, which are molded with the polystyrene body and feature transverse ribs and holes for enhanced anchoring, to increase cohesion and mechanical strength of the spouts without increasing thickness.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If the interjoist is made of polystyrene to provide thermal insulation, then the thermal insulation performance is improved, but the mechanical strength is insufficient requiring increased thickness

Engineering Contradiction:
Improvethermal insulationVSAvoidmechanical strength
Core Design Contradiction:
TemperatureVSStrength

Solution Approach 1:

The interjoist combines polystyrene body with steel stiffeners to create a composite structure. The polystyrene provides thermal insulation while the steel stiffeners provide mechanical strength, resolving the contradiction between thermal insulation performance and mechanical strength requirements.

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

The interjoist is divided into functional segments: the polystyrene body for thermal insulation and the steel stiffeners for mechanical reinforcement. This segmentation allows each material to perform its optimal function without compromise.

Inventive Principle:
Principle #1Segmentation

2Strength

If the thickness of the spout is increased to improve mechanical strength, then the load-bearing capacity is improved, but the beam height and weight increase

Engineering Contradiction:
Improveload-bearing capacityVSAvoidbeam weight
Core Design Contradiction:
StrengthVSWeight of stationary object

Solution Approach 1:

By incorporating steel stiffeners within the polystyrene spout, the structure achieves high load-bearing capacity without increasing overall thickness. The steel reinforcement provides strength while the thin polystyrene outer layer maintains lightweight characteristics, avoiding beam weight penalties.

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

The steel stiffeners are strategically positioned within the spout structure where mechanical strength is most needed. This localized reinforcement provides high strength-to-weight ratio, improving load-bearing capacity without uniformly increasing thickness throughout the entire spout.

Inventive Principle:
Principle #3Local quality

3Reliability

If the keying height is increased to meet minimum requirements for prestressed beams, then the connection function is improved, but the beam height increases

Engineering Contradiction:
Improveconnection functionVSAvoidbeam height
Core Design Contradiction:
ReliabilityVSLength of stationary object

Solution Approach 1:

The steel stiffeners extend into the keying region, providing mechanical reinforcement that enables the spout to achieve minimum keying height requirements without increasing overall beam height. The composite structure maintains connection reliability while minimizing beam height penalties.

Inventive Principle:
Principle #40Composite materials

Data Source

PatentEP2559821B1Formwork element made of low density material
Publication Date: 2019.03.27 KP1
  • EP2559821B1 patent drawingFigure 1~2
  • EP2559821B1 patent drawingFigure 3

AI summary

The floor unit (1) has a body (2) made of low density material and provided with two longitudinal edges (6, 7) with nozzles (13, 17) extending transversely. The nozzles are supported on inverted T-section-type beams. Stiffeners (19, 21) are made of material having strength higher than that of the body of the unit. The stiffeners are arranged to increase cohesion of the nozzles with the body of the unit, where the stiffeners are in a form of Z-section defining an upper portion. The stiffeners are made of plastic.