Revisiting the Drainage Coefficient of the AASHTO93: A Method for Improving Local Flexible Pavements Design

Erdrick Leandro Pérez-González, José Vicente Heredia, Jean-Pascal Bilodeau — Mon, 30 Sep 2024 00:00:00 +0000

The AASHTO93 guide is widely used in pavement design and is considered the primary reference in road construction and management for many countries worldwide. One important parameter used in the AASHTO93 design method is the drainage coefficient, which considers the impact of saturation on the stiffness of granular materials. However, selecting this parameter can be associated with high uncertainty in practice. With the knowledge gained from applying this methodology and advancements in current research on granular materials, it is possible to revise this parameter to achieve optimal results. This work aims to review the basics of the drainage coefficient and introduce a more logical approach to define the proper parameter for local conditions. The goal is to enhance pavement design practices in administrations that utilize the AASHTO93 method, particularly those with no intention of transitioning to advanced techniques like the mechanistic-empirical approach or where alternative approaches are still minimal.

Effect of Time Delay on Semi-Active Seismic Control of a Nonlinear 11-Story Building Using Floating and Predictive Fuzzy Logic Algorithm

Akbar Bathaei, Seyed Mehdi Zahrai — Mon, 30 Sep 2024 00:00:00 +0000

In control systems where sensors and receivers of sensor recorded data are used, there is a possibility of time delay in transferring recorded data of structural motion, which is a factor to reduce the efficiency of control system and even destabilization of structure. In this paper, the effect of time delay on performance of semi-active seismic control of an 11-story building with Magnetorheological (MR) damper is studied using predictive and floating fuzzy logic algorithm. Fuzzy decision-making system and linear and nonlinear model of structure are implemented in MATLAB and OpenSEES, respectively using TCP/IP connection. According to the results of incremental dynamic analysis for seven earthquakes with maximum acceleration of 0.1 to 1.0g and incremental step of 0.1g, floating fuzzy control system has improved roof displacement response of the structure by 38.75% compared to the uncontrolled system, despite time delay of 0.1s in control process and improvement roof response of the structure with linear behavior by no time delay in fuzzy control system based on velocity. In the case of time delay in control system and application of fuzzy decision making system based on roof velocity of the structure and predictive control, the average improvement of structure displacement response is 24.91% compared to uncontrolled system and it is 27.51% in the case of using floating fuzzy system. The same values in nonlinear structure are 30.81, 20.19, and 22.84%, respectively.

Journal of Civil Engineering and Construction

Revisiting the Drainage Coefficient of the AASHTO93: A Method for Improving Local Flexible Pavements Design

Effect of Time Delay on Semi-Active Seismic Control of a Nonlinear 11-Story Building Using Floating and Predictive Fuzzy Logic Algorithm