Examples of services provided
Structural connection failure investigation
An emergency call was received from a contractor installing 25,000 pound concrete panels on a new building in San Jose, CA. The specialty bolts being used to attach the panels were stripping out of the nuts. I inspected the components onsite, collected samples of the nuts and bolts and load tested them that day. Based on these preliminary tests, I designed and implemented an extensive test program within a few days in order to quantify the variables related to the problem and provide detailed recommendations to remedy the deficiencies. This work involved statistical analysis and determination of appropriate safety factors.
Excavation shoring injury
While disassembling an Oakland Bay Bridge excavation shoring system, a 2400 pound steel trench shield tipped over and crushed a workman against a concrete foundation. I found that the design and procedures were inadequate and did not comply with the California “Construction Safety Orders” within Title 8.
I found that the engineering, structural tests and analysis of the structural test results were inadequate in determining the safe load capacity of an Oakland Bay Bridge mobile scaffolding system which collapsed and killed a worker.
Fire truck collision at an intersection
In this case I installed accelerometers, external “fifth wheel” speed pickup and brake pedal application switch for data acquisition during tests at the accident site. The data was recorded continuously by means of a laptop computer. The brake application time lag, braking distance and stopping time were determined for a fully loaded fire truck.
Film reconstruction time/position study
During a film reconstruction of the collision of two vehicles traveling at highway speeds I provided and operated a data acquisition system to record the speeds and positions of the exemplar vehicles in the film.
Tire blow out
I installed a system of valves in a tire rim in order to rapidly deflate a tire. Using an instrumented exemplar vehicle we were able to repeatedly simulate a tire blow out and study the potential for loss of control.
A project involved installing more than 100 strain gauges on steel and aluminum structural elements of a transit bus and recording dynamic data on actual transit routes. Strain gauges measure local deformations (strain) within structures and the measured strains can be used to determine the actual compression, tension and shear stresses in structural elements. Strain gauge rosettes were used to completely solve Mohr’s circle. Strain gauge measurements can be made statically or dynamically in either the laboratory or the field.
Slip and fall
A customer slipped and fell on a new floor in the entry of a restaurant on a rainy evening. I measured the slip resistance of the floor and found it to be slippery when wet. I reviewed construction documents from the contractor and the architect and found that the property owner had reason to believe that he had purchased a slip resistant flooring system.
Sidewalk tripping hazard
A sidewalk was repaired after a pedestrian tripped and fell on a vertical offset in the walkway surface. Since the defect no longer existed, I used snapshots taken at the time of the accident and photogrammetry techniques to determine the dimensions of the original offset.
Construction and design defects in buildings
Physical inspections of structural elements were performed and inadequate nailing of shear walls and other defects were found. Review of design documents found inadequate structural detailing and errors in structural calculations. Plaintiff and defense experts worked together to develop a consensus in regard to both the extent of the defects and the required repairs.
Shear wall tests
A series of full scale plywood and gypsum wallboard walls were constructed and tested to determine the energy absorbing and strength capacity of various shear wall assemblies during seismic events.
Light rail fastener fatigue load tests
I designed, built and operated a test system for elastomeric pads designed to attach rails to concrete. Loads of up to 24,000 pounds were applied for as many as 3 million cycles.
Tire mounted on oversize rim
15 inch tires were mounted on 15.5 inch rims resulting in failure of the steel bead and explosion of the tire. Tire pressure was documented and the explosion videotaped. During the tests, the tires are explosively launched at speeds on the order of 100 miles per hour with massive destructive force.
Tire exploded with flat repair product
This case involved a repair shop worker who attempted to repair a pinhole in a tire rim with a welder. In our tests, a tire was filled with a canned, pressurized flat repair product containing propane/butane. A spark was triggered inside the tire and the fuel and air mix inside the tire exploded destroying the tire and launching the rim at high energy.
A woman stepped outside onto a third floor balcony for a cigarette with a friend. She leaned on the railing which failed and she fell to her death. I inspected the accident site to determine code compliance and condition of the railing.
A research company had a wooden, non electromagnetic interference tower designed and constructed to support a satellite communication dish. The tower was found to vibrate excessively and I was brought in to assess the problem and design repairs.
Rocket propellant processing facility
I was asked to evaluate the structural condition of a concrete blast resistant structure which had been out of service for several years. The company wanted to reactivate the solid propellant grinders in the tower and wanted to know if the exposure to caustic chemicals, weather and time had rendered it unsafe.
Fire resistance of GFRC
I coordinated the construction, instrumentation and testing of a full scale GFRC (glass fiber reinforced concrete) architectural exterior wall assembly for fire resistance.
I provided the architectural cladding system structural design and details for a building located at Wilshire Boulevard and Palm Avenue in Los Angeles. The cladding system is lightweight GFRC with an unusual seismic resistant structural system.
A wheel chair went out of control inside a San Francisco airport jet way. There being no aircraft present at the time, the occupant of the wheel chair fell from the jet way to the concrete apron. A wheel chair was instrumented and tested at the site. I provided the instrumentation and drove the wheel chair during investigative testing.
Water tower fall
A workman climbing a water tower claimed he fell from the ladder when the hydraulic surge from a starting pump shook the tower. I climbed the tower with accelerometers and a computer in order to measure and record the intensity and frequency content of the vibrations.
Cable car collision
I investigated an accident involving an automobile making a left turn in front of a cable car. I studied the starting and stopping capabilities of a cable car, the control systems linking the cable cars to the traffic signal lights and the acceleration of an exemplar automobile. A film reconstruction was conducted. The film reconstruction was performed in real time since cable cars have only one speed.
Bicycle accident on Haleakala
A bicyclist lost control in a corner while descending the mountain on a rental bicycle and was run over by an ascending bus. Riding an exemplar bicycle from the rental company, I investigated the speed and cornering capabilities of the bicycle at the accident site. I later instrumented the bicycle to measure the braking capabilities considering variables such as wet roads, front brake application, rear brake application and body position. I also preformed tests to demonstrate the stability of the bicycle.
A customer was injured when a chair collapsed at a shopping mall food court. I tested exemplar chairs for stability, strength and compliance with applicable standards.
Low speed crash
After instrumenting the vehicle with accelerometers and speedometers, I sat in a Mercedes Benz and collected high speed data as it was rear ended by an SUV.
I developed a method to dynamically measure vehicle bumper height while braking in a collision/override case.
By failure analysis and testing I was able to reconstruct the catastrophic failure of a bicycle fork. The force require to fail the fork was higher than the friction force that the weight of the bicycle and rider could develop. I showed that when the front wheel locks, the rider and bicycle are accelerated upward generating a large downward vertical force. This dynamic vertical force combined with the weight of the bicycle and rider was great enough to develop a friction force sufficient to fail the fork.
falsework intended to support the construction of a concrete
overpass collapsed during assembly killing one worker and
several. By reviewing photographs of the failure, construction
documents and testimony of survivors, I was able to identify
instability that triggered the collapse.
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