Structural Optimization of Uniform Strength Noise Barrier

Abstract

Traditional approaches to noise barrier design often rely on outdated techniques and resource-intensive materials like concrete and steel. However, with sustainability gaining prominence, aligning noise barrier design with green construction principles becomes crucial. Structural optimization, aimed at minimizing material usage, emerges as a promising strategy to mitigate environmental impact. This study focuses on determining the optimal geometry of a noise barrier composed of low-tensile strength material, under the influence of self-weight and uniformly distributed lateral load.

The methodology employed addresses this question through a series of key steps. Beginning with a two-dimensional analytical form-finding process, optimal cross-sections are derived for the noise barrier. The application of uniform strength theory, known for its efficiency in generating material-effective structures, results in constant stress shapes. These solutions are validated using Finite Element Analysis (FEA) to ensure conformity with predefined stress criteria. Subsequently, numerical structural optimization is conducted to achieve minimum weight geometries that adhere to stress constraints, utilizing a penalty function. The validation process involves comparing numerically optimized geometries with analytical solutions, confirming their reliability and mutual consistency. This validated optimization approach is then extended to three dimensions, exploring the optimal combination of longitudinal profiles and varying cross-sections along the barrier.

Analytical solutions for 2D uniform strength cross-sections of the noise barrier differ based on load conditions. For self-weight, an exponential function describes constant stress, ensuring uniform compressive stress across the structure. Conversely, under uniformly distributed lateral load, a linear function depicts constant maximum bending stress along the height. The interaction between self-weight and lateral load results in symmetric geometries defined by specified constant tensile stress. A square root geometry guarantees constant zero tensile stress, offering advantages like reduced need for additional structural elements and practicality in real-world scenarios.

A significant distinction arises between 2D cross-section and 3D structural optimization regarding bending capacity. In three dimensions, the entire structure contributes to bending resistance by shaping itself. Releasing the rotational degree of freedom at the bottom support enables the generation of a corrugated longitudinal profile, enhancing bending stiffness. This corrugation distributes bending moments over longer spans, reducing stress and material requirements. Notably, the optimized corrugated profile exhibits enhanced bending stiffness, minimizing the impact of practical constraints.

In summary, this research provides insights into optimal geometries for free-standing structures, highlighting the efficiency of analytical and numerical approaches. The numerical optimization framework proves highly effective and efficient, contributing valuable insights to noise barrier design within a sustainable framework.