Second-Order Effects in Lightweight Aggregate Concrete Slender Columns

Area of Science:

• Civil Engineering
• Materials Science

Background:

• Lightweight Aggregate Concrete (LWAC) offers a potential substitute for normal-density concrete in structural applications.
• Slender structural elements are susceptible to second-order effects, influencing their load-bearing capacity.

Purpose of the Study:

• To analyze the behavior of slender columns made from LWAC and normal-density concrete under eccentric loading.
• To investigate the influence of varying longitudinal reinforcement ratios on column performance.
• To evaluate the accuracy of existing models in predicting LWAC column behavior.

Main Methods:

• Experimental testing of slender columns (slenderness ratio λ = 74) made of LWAC and normal-density concrete under eccentric load.
• Inclusion of elements with two longitudinal reinforcement ratios (0.9% and 2.3%).
• Simulation of experimental results using established literature models.

Main Results:

• LWAC columns displayed greater displacements and reduced load-bearing capacity compared to normal-density concrete columns, despite similar compressive strengths.
• The difference in performance was attributed to the significantly lower modulus of elasticity of LWAC.
• This performance disparity was more pronounced in columns with lower longitudinal reinforcement ratios.
• Literature models demonstrated inaccuracies in predicting the elastic modulus and limit strain for LWAC.

Conclusions:

• The lower elastic modulus of LWAC is a critical factor affecting the performance of slender columns.
• Existing predictive models may not adequately capture the behavior of LWAC elements.
• Experimental determination of LWAC's elastic modulus and limit strain is crucial for accurate structural analysis and design.