 |
Pavement Design and Performance Modeling
Manager: Vacant
Overview
The Pavement Design and Performance Modeling Program performs experimental/analytical research to better understand relationships between heavy trucks and the infrastructure on which they travel.
Controlled load tests are conducted to establish how a pavement responds to dynamic loading.
Accelerated pavement testing (APT) is conducted as well to determine the relationships between repeated loading and pavement damage. Mathematical models are created to simulate these experimental results for performance prediction of pavements subjected to heavy-vehicle loading.
Demonstration projects and technology transfer activities are supported by the experimental and analytical aspects of the laboratory to encourage the transition of current state-of-the-art research results to practice.
This laboratory performs much of its research in conjunction with partnering agencies (State departments of transportation, other FHWA teams and offices, other Federal administrations, and academia) using:
- In-Service Test Roads. Test sections are instrumented with gauges to collect strain, displacement, pressure, and temperature data. These data are collected while controlled loading is applied by a heavy vehicle exhibiting various characteristics, including payload, tire type, tire inflation pressure, axle configurations, speed, and suspension type. Experiments are performed seasonally to identify the environmental effects on pavement response. Test sections include pavements at TFHRC; at WesTrack in Nevada; in Louisiana, Ohio, and Texas; and on test roads used in the DIVINE (Dynamic Interaction Vehicle-INfrastructure Experiment) and
Long Term Pavement Performance (LTPP) programs. Data from these facilities are used for calibration and validation of pavement-response models.
- Accelerated Pavement Testing Facilities (APT). APT's apply a repeated load to select pavement sections using a machine fitted with a wheel to simulate heavy-vehicle traffic. Several different versions of these machines are in service across the globe, each having unique features. The work of this laboratory is supported by the TFHRC Accelerated Loading Facility (ALF); the Texas Mobile Load Simulator (MLS); and an indoor facility in Ohio, which features environmental control. Depending on the facility, variables such as loading frequency, speed, load, environment, wheel wander, and tire type can be introduced. These tests are typically run until pavement failure occurs, while collecting data such as pavement strain, deflection, temperature, and loading cycles. Results from these experiments are used for calibrating and validating pavement-damage models.
- Dynamic Wheel Load and Pavement Profiler Test Vehicle. The test vehicle at TFHRC is a single-axle flatbed with a gross vehicle weight (force) of 33 kips. The vehicle is equipped with strain gauges and accelerometers on the axles to measure shear strain and acceleration, respectively. Accelerometers are also located at the front and rear of the chassis to measure relative accelerations between the vehicle suspension and body. Triangulation laser profilometers are mounted on the driver and passenger sides of the vehicle for simultaneous road profile and dynamic load measurements. This vehicle is also capable of being equipped with either steel- or air-spring suspensions. All data are collected by onboard data acquisition systems consisting of signal conditioners, amplifiers and portable computers, and analog-to-digital converter cards. Data are analyzed to determine relationships between the road profile and the dynamic response of the vehicle for validation and calibration of a vertical vehicle dynamics model.
- DYNamic TRuck ACtuator (DYNTRAC). DYNTRAC is a shaker table consisting of hydraulic actuators that support a truck and apply a forcing frequency through the tires/ wheels and to the suspension. A range of forcing frequencies is applied while modes of vibration are identified and wheel forces are measured. The shaker table was used in conjunction with instrumentation on the TFHRC test truck to determine unknown parameters such as the mass outboard, the suspension instrumentation, spring stiffness, and shock absorber damping coefficient. These parameters are included in the truck vertical dynamics model.
- MODULUS Tire-Pavement Interface Pressure Pattern (TPIPP) Transducer. This device allows measurement of the vertical contact pressure magnitude and distribution occurring at the interface between the tire and the sensor surface. The device can measure TPIPP's under various tire types, inflation pressures, loads, and speeds. TPIPP's are used as an accurate input to mechanistic pavement-performance prediction models.
.....................
Back to Laboratory List
|
|
