By: Vahe Hovsepian
Forty-five years ago, I started a new adventure with Parsons, and since then I’ve had the opportunity to work on iconic projects across five continents and the Arctic. Many have asked why I’ve stayed with one employer so long!
There are many reasons. One is the desire to be involved with projects from start to finish – to see the projects I’ve designed come to life! Another is the diverse and interesting opportunities. Different services, different types of projects, working overseas and getting to know different cultures.
Innovation In Focus
As a lifelong learner, I enjoy bringing innovative engineering solutions to technically challenging projects. There have been too many to mention, so I’ll share a few examples:
Salt Waste Processing Facility and Next Generation Solvent Deployment in Aiken, South Carolina, where I am Senior Engineering Manager, Technical Staff, and Construction Support Lead.
The SWPF project is a first-of-a-kind nuclear facility that is subject to the most exacting safety and quality requirements. It was recognized as Project of the Year by the American Society of Civil Engineers, South Carolina section (ASCE SC), and it was selected for a World Quality Month, Quality Excellence Spot.
Innovative thinking brings solutions to every element of a project.
At SWPF, that included integrity of the Central Processing Area building’s massive slab foundation. At 33,000 square feet in area and 8 feet thick (considered mass concrete), we needed to ensure the concrete didn’t crack as it cured. This can happen if the temperature differential between the internal core and the top surface isn’t controlled, and we integrated multiple techniques to achieve proper curing.
The first technique was controlling the temperature of the delivered concrete. We pre-cooled the concrete by adding liquid nitrogen at the batch plant. After the concrete placement, exposed surfaces were covered with insulating blankets to slow the escape of heat from the surface and reduce the temperature difference within the concrete.
Before the concrete placement, temperature sensors connected to a recording system were installed at the concrete core and at a couple of inches below the concrete surface. This enabled daily temperature monitoring to ensure that the core temperature and the temperature differences did not become excessive, and they provided the information to know when to stop thermal control activity.
Conventionally the insulation blankets are not removed until the end of the thermal control period. Based on the temperature readings, we were able to remove the insulation blankets during the day time and shorten the thermal control period. This also allowed us to perform work above the concrete placement and prepare for the next stage of construction.
We also innovated the structural support within the matslab by using light structural steel frames instead of conventional rebar chairs. These frames hold the rebar and support numerous pipes and conduits embedded in the foundation.
Finally, in lieu of conventional wood planks, welded wire reinforcement (WWR) was placed on top of the top layer of the matslab reinforcing steel. WWR has tighter spacing that allowed workers to safely walk on the mat before and during concrete placement. In addition, the WWR helps reduce concrete shrinkage cracks.
Los Angeles International Airport Second Level (Departure Level) Roadway, in Los Angeles, California, where I was Project Structural Engineer.
This project was completed prior to the 1984 Los Angeles Summer Olympics, yet it’s memorable because it involved unique solutions that were new at the time. The Second Level Roadway is a prestressed concrete bridge that is about 3.5 miles long, involving sharp horizontal curves with small radii, and it had to align with the second level (departing level) of the existing terminal buildings, as well as the upper level of existing parking structures.
We designed the superstructure in front of the terminal buildings using precast, pre-tensioned, trapezoidal box girders, each weighing 80 tons. After placing the girders, all construction activities, including the construction of the roadway deck, were performed at the top of the girders, so there was minimal impact on pedestrian and vehicular traffic.
At other locations, the superstructure was designed as cast-in-place post-tensioned single-box girders with internal webs. For the locations with sharp horizontal curves with small radii, the design was challenging in calculating loads, and we included special details such as thicker webs with reinforcing ties and hairpins at a closer spacing to ensure the concrete wouldn’t crack during tensioning of the tendons. At the time, design guidelines for curved bridges were mainly geared toward structural steel bridges, and we paved the way regarding structural design of concrete bridges with sharp horizontal curves.
Most of the Second Level Roadway piers/columns above the ground were short in length and therefore rigid. To increase flexibility and seismic resiliency, each pier was supported by a single cast-in-place caisson in lieu of conventional pile caps with multiple piles. This delivered benefits similar to increasing the column length to reduce seismic forces. The piers were also located within the existing ground-level roadway median or sidewalk; thus, during construction of the caissons, there was no need to close existing roadway lanes, which would have been required if pile caps with multiple piles were used.
The construction went smoothly as planned, with no design errors, and it was completed ahead of the schedule.
Twilight Zone Tower of Terror in Orlando, Florida, where I supervised and coordinated the engineering design. This project comprised a complex building for a 15-story ride/attraction with free-drop elevators. At 199 feet, it was the tallest attraction at the Walt Disney World Resort at the time. In order to achieve the weightless effect, cables attached to the bottom of the elevator car pull it down at a speed slightly faster than what a free fall would provide.
Like the other projects I highlighted, the Tower of Terror was an opportunity to bring engineering innovation to solve a challenge, and it required me to go on site for exacting construction quality control and quality assurance.
This was a first-of-its-type ride, and it was repeated in California, France, and Japan. Motors used for the elevators are 3 times bigger than the largest high-speed elevator motors, and they were specially created for the Tower of Terror.
Career Advice
I’ve enjoyed mentoring many colleagues over the years, helping them grow their professional and applied knowledge. What career advice would I share?
1. Don’t be afraid to take on challenges, and to come up with sound innovative ideas.
2. Keep learning and expand your knowledge and skills with every project.
3. Get out of the office and go on-site to learn from the expertise of other professionals, to learn the specifics of construction and construction methods which will help you improve your engineering and help you learn from any errors, as well as the solutions, and improve in implementing constructability in engineering design.
4. Accept foreign assignment when you can. In addition to growing your career on interesting/mega projects, it will improve your communication skills, build on confidence and independence, and expand your cultural awareness, professional network, and financial rewards.
A career in engineering has given me endless opportunities to make the world a better place. After 45 years with Parsons, I’m still innovating!