The Powell Family Structures and Materials Laboratory is located on the East Campus of the University of Florida and is part of the Department of Civil and Coastal Engineering. The facility consists of a 6000 square foot lab space with a 30-foot high ceiling and 4-foot thick concrete strong floor, a 2000 square foot machine shop with a 12-foot ceiling, a 5000 square foot general lab space with a 16-foot high ceiling, a 120 linear foot wind tunnel, a 220 square foot instrumentation room, and several offices & storage rooms. Research in this facility is primarily directed at earthquakes, hurricanes, tornados, and blast/impact in the context of structural damage mitigation and human intervention.
Accelerated Aging Chamber
Most accelerated weathering chambers (e.g., the QUV manufactured by Q-Lab) are significantly smaller in capacity. Therefore, the Department of Civil and Coastal Engineering built a large accelerated weathering chamber to conform to the requirements for accelerated weathering of bituminous materials set forth in ASTM D4799-08, ASTM G151-10, and ASTM G154-06. The chamber has plan dimensions of 1.4 m by 4.9 m (4 ft 6 in by 16 ft) and a water spray retention basin with a chamber height that slopes from 0.30 m to 0.48 m (1 ft to 1 ft 6 in).
Environmental conditions are controlled and monitored using National Instruments Labview software and a National Instruments CompactDAQ data acquisition system. The UV light system consisted of 1.2 m (4 ft) long UVA 340 lamps, manufactured by Q-Lab, located 102 mm (4 in) above the specimens at an on center spacing of 102 mm (4 in) to ensure irradiance uniformity. The lamps produced peak irradiance at a wavelength of 340 nm, and were powered by fluorescent light ballasts using an overdriving technique to produce a maximum irradiance at the specimen level of 0.72 W/m2 at 340 nm. The irradiance output is 0.04 W/m2 (at 340 nm) greater than the irradiance of the sun at noon on a clear day (Fedor and Brennan, 1996).
ASTM G151-00 Section 5.1.2 specifies that the irradiance at any point in the specimen area must be within 70% of the maximum irradiance measured in the same area. The irradiance is inversely correlated to the ambient air temperature near the light and, over time, the irradiance output can decrease. Therefore, the irradiance of the UV light system is periodically recorded at 25 mm (1 in) increments using an Apogee SU-100 attached to a single-stage gantry affixed to the centerline of the chamber.
Variable weight Drop Hammer with 12’-6” drop height and variable weights between 100lbs and 900lbs. 7,000lb Drop Hammer with 15’-6” Drop Height.
High Airflow Pressure Loading Actuator (HAPLA)
This apparatus is based on the pressure loading actuator system (PLA) developed by the University of Western Ontario (UWO). This system pictured below to the left is used to apply time-varying pressure to surfaces of buildings and other structures demonstrated below to the right. The HAPLA consists of two 75hp centrifugal blowers connected to a valve with a rotating central disk actuated by a servo motor. The servo controls the disk’s position, which in turn regulates the system pressure. The valve can be set anywhere from full pressure to full suction. A test specimen duct can then be connected to the outlet side of the duct, making it possible to test windows, doors, soffit, etc.
The lab is equipped with several load cells including flat (or pancake) load cells, S-type load cells, and cantilever load cells. The load cells range from 25lbs to 200kips.
The lab houses an indoor impact pendulum consisting of a 14-foot-high steel frame capable of swinging weights up to 1,600 pounds through an arc with a vertical drop height of up to 3.3 feet.
Pneumatic Actuated Uplift Gantry System
In order to replicate wind uplift conditions, a pneumatic actuator was developed on an overhead gantry system to test various connections. With this system accompanied with multiple load cells influence functions can be developed on various load paths. The picture below is testing the correlation between roof uplift and resulting loads at the foundation of the model.
Six Degree of Freedom Shake Table
Recently installed in the lab is a 4ft x 4ft six degree-of-freedom shake table with a one-ton payload and ±6 inches of stroke in each of the x-, y-, and z-directions. The shake table is powered by a 125HP Hydraulic Power Unit capable of pressures up to 3000 psi. The complex motion generation capabilities of the shake table will enable testing and monitoring of the structural response of scale models and components in a controlled environment.
The lab has an 80’ x 32’ strong floor that is 4’ thick and has mounting plates 4’ on center. This allows large loads to be anchored into place using the anchor points with a 200kip capacity.
Universal Testing Machines
A Universal Testing Machine, or UTM, is a machine that allows samples to be tested in pure tension or pure compression. Currently we have two tension machines capable of testing various building products. As seen below you can see the two testing machines available at the lab.
The Instron 3367 has a load capacity of 6,750lbf and maximum speed of 20 in/min.
The Uplift Testing Apparatus capable can apply fluctuating loads on asphalt shingle tab seals (following ASTM D6381 test setup). This portable system performs mechanical uplift testing on existing homes.
Under development is a 120’ x 20’ Boundary Layer Wind Tunnel. It is powered by 2.09 MW (2800 HP) composed of four 0.52 MW (700 hp) marine Detroit Diesel engines that spin eight hydraulically actuated vaneaxial fans. To recreate the boundary layer profile an active computer control system modulates wind speed by varying fan RPM that pass through several screens and honeycombs before it reaches the test specimen. The control system utilizes a PID-control system operated in the LabVIEW environment.
Windborne Debris Simulators
We custom-built two windborne debris simulators, which simulate typical impact scenarios observed in the field.
The first system is a launching apparatus designed to propel flat projectiles (e.g., asphalt shingles).
The second system is a capable of launching compact missiles, such as 2x4s and roof tiles. The apparatus is comprised of four major components; the pneumatic ram that propels the projectile along a guided track toward the target, the air reservoir tank and barrel that supply propulsion force to the ram, the electronic butterfly valve that releases the pressure from the tank to the barrel, and the integrated electronic system which monitors projectile speed and maintains the desired tank pressure.
The lab is equipped with a 2000-square-foot machine shop with metal and wood working capabilities. This shop is outfitted with sufficient 110/220V electrical outlets and a centralized pneumatic air system. The lab also contains a central tool rack to store all portable tools.
The machine shop has the capability to fabricate and machine steel and aluminum parts of various sizes. The shop contains the following machines listed below.
- Bridgeport Series II Mill
- Craftsman 20 in 2HP Drill Press
- Clausin Drill Press
- Wilton 14″ Vertical Band Saw
- MSC Vertical Band Saw
- Delta Model 9 Horizontal Band Saw
- Dual-Wheel Grinder
- Multiple Bench top Grinders
- Millermatic 252 Mig Welder
- Miller Syncrowave 180SD Tig Welder
- Campbell Hausfield WS2800 Stick Welder
- South Bend Large Lathe
- Jet 1240P 2Hp Lathe
- Acetylene Torch (Small and Large)
The machine shop is equipped with multiple tools to construct wood test specimens listed below.
Howard Electronics Soldering Stations (988D and 850D).
- Data Acquisition Systems
- High Speed & Motion Tracking Cameras
- NEC High speed video camera capable of recording 100,000 frames per second.
- Phantom High Speed Camera V5.2 capable of recording 148,000 frames per second
- 3 Natural Point OptiTrack Motion Tracking Cameras
- Water Measurement Devices
- Multiple OTT Parsivel Distrometers
- One Droplet Measurement Precipitation Imaging Probe (PIP)
- Wind and Pressure Measurement Devices
Bench Top Ovens and Moisture Analyzers
Ovens and moisture analyzers are used for a variety of research projects in order to preheat and measure moisture content of specimens. In order to accommodate this there is a variety of heating equipment available for use in the lab. Currently there is an Imperial V Laboratory Oven, Excalibur Food Dehydrator, and a Denver Instrument IR35 available for a variety of research projects.
Various research projects require transporting heavy objects from storage to the testing platform. In order to accommodate the lab is equipped with the following equipment:
Several research projects require the collecting of field data to accurately replicate experiments in the lab. Below are several field experiments that are based out of Powell Lab.
Florida Coastal Monitoring Program (FCMP)
The Florida Coastal Monitoring Program (FCMP) is a unique joint venture focusing on full-scale experimental methods to quantify near-surface hurricane wind behavior and the resultant loads on residential structures.
There are several houses that are demolished every year due to flood, wind, and water damage. Before these houses are destroyed we send a team of engineering students to collect and test various building components. Some of these components are tested in the field while others are collected and brought back to the lab for future testing. These include but are not limited to roof to wall connections, nail pullout strength, sheathing to truss connections, and window & door installations.
Post Damage Assessments
After a hurricane makes landfall leaving a destructive path in its wake, engineering students survey the damage to residential and commercial areas. With this data we can analyze failures in the building product installations and create recommendations to prevent future damage.