Dr. Mal Sacks, a pioneer in the development of tuned mass dampers, passed away on Nov. 19, 2018. He was 75 years old. Over the course of his 40-plus year career, Mal was responsible for designing damping systems for a host of high-profile projects, many of which were done in collaboration with Thornton Tomasetti.
A specialist in theoretical acoustics and vibration, Mal’s first TMD project was CN Tower in Toronto, Canada, in the late 1970s. Its pendulum damper system comprised two steel rings, each containing 9 metric tons of lead, that were supported by three steel beams connected to the building’s 555.3-meter-tall antenna. It is widely credited for helping to usher in the modern era of TMD design. His other interest was the measurement of sound of combustion systems. Mal developed special techniques and worked on many projects. His longtime associate in this area, Ramin Behboudi, joined Swallow Acoustic in 2014 when Mal retired and is now an associate principal in Thornton Tomasetti’s Mississauga office.
Mal Sacks, left, and John Swallow on site at Chicago’s Soldier Field. The two teamed up with Thornton Tomasetti on the renovation of the Chicago stadium, which was completed in 2003.
Mal first teamed up with Thornton Tomasetti in 1988 on Manhattan’s Fiorello H. LaGuardia High School of Music & Art and Performing Arts. This alliance continued for many years and involved many iconic structures, including the 46-story, 275-meter Chifley Tower in Sydney, Australia. Here, too, a passive, pendulum-style damper was selected. A 400-metric-ton steel block was suspended from the top of the building and connected to a hydraulically damped gravity system to help reduce building sway.
When Chicago’s historic Soldier Field stadium was renovated in the early 2000s, we worked with Mal and the acoustical engineering team to perform a finite element analysis of the upper west grandstand, which showed vibration levels that exceeded normal limits as a result of dynamic crowd loads. The team devised a system consisting of 21 TMDs along the grandstand’s perimeter, covering an area of nearly 1,000 linear feet, with 840,000 pounds of sprung weight. It also developed a 64-channel permanent vibration monitoring system (PVMS) to monitor the motion of the rakers and TMDs.
Some of Mal’s other collaborations with Thornton Tomasetti include the Qatar National Convention Center in Doha and two potential TMD’s for skyscrapers and the New 42nd Street dance studios, all of which are in Manhattan.
Mal Sacks, left, John Swallow and Ramin Behboudi testing a tuned mass damper in San Angelo, Texas.
Most of Mal’s signature projects were done in partnership with longtime colleague and friend, John Swallow. The two met at the University of Toronto and worked together at Vibron. Mal eventually went on to form Tacet Engineering, while John founded Swallow Acoustics, which in 2017 merged with Thornton Tomasetti. The two, however, continued to collaborate, working on more than 20 TMD projects.
Here, John shares his remembrances, as well as those of some of Mal’s other project partners and friends, of a skilled and innovative professional and caring, thoughtful man.
Mal and I first met as students of Professor Don Allen at the University of Toronto in September 1972. Originally from New York City, Mal and his wife, Diane, moved to Canada in 1969, and he pursued his master’s degree and Ph.D. at U of T. I remember meeting them at a faculty party. He and Diane shared the same honesty, sincerity and genuine love of the people in their lives. We’ve been friends and colleagues ever since, and Diane was pediatrician to my children and those of many friends.
A bit of history: at the time Mal was studying acoustics and reactive mufflers, while I had started looking at vibration and damping. Don, meanwhile, had an interest in floors and reducing vibration. He had already installed two TMDs on a floor at his daughter’s school. Don was an inventive engineer. He saw every problem, be it some tiny mechanism or noise issue throughout a skyscraper, as an interesting challenge.
In early October 1973, Don came to me and said he had been approached to provide two TMDs for the CN Tower, which was under construction in Toronto. It was the most exciting engineering and construction project at the time in Canada and possibly the world. He asked if I would be interested in designing the TMDs for it, since I had been studying damper systems. Although I was totally intimidated, I agreed to give it a try. Don also spoke to Mal, his other student, about the project. Once I recovered, I met them a few hours later and Mal already had a proposal and calculations for two TMDs, one regular and one inverted pendulum. Mal’s designs were built by Don’s company, Vibron. I learned such lessons from those great engineers that day.
Mal Sacks’ design for Toronto’s CN Tower called for two tuned mass dampers, one at 1700 feet and another at 1750 feet.
Mal and Don were both very comfortable in any academic, engineering or construction environment and we all learned from them. Ron Lake, a fellow student and friend who joined Vibron, said: “I had the pleasure of working for Mal. He taught me how to technically manage a project and how to conduct oneself on a job site. He was a true leader.”
Hans Jensen of Flack + Kurtz Australia collaborated with Thornton Tomasetti legacy firm Lev Zetlin on the design of Chifley Tower. Mal’s Tacet Engineering was the specialist damping consultant, I was overseeing dynamics, hydraulics and electrics, and Hans was charged with designing the structure to accommodate gravity and dynamic loads from the TMD during installation and operation. “Mal’s TMD design for Chifley is simple, yet elegant, innovative and efficient,” Hans said. “While it took Mal some time to teach the local TMD contractor how energy dissipation cylinders work, his quiet professional and persuasive manner soon won the day. Other obstacles to overcome included the reluctant building owner and his recalcitrant project manager. But again, Mal’s convincing and winning style helped push the project along, so, at long last, the TMD was successfully tested, commissioned and handed over to the client in early 1994.”
Mal Sacks, left, with wife Diane, Hans Jensen and Susan Foy at the Deerhurst Resort in Ontario, Canada in late 1994. Photo courtesy Hans Jensen.
Mal could be very inventive. Manny Velivasakis, a former Thornton Tomasetti managing principal, approached Mal about a floor vibration issue at a project in New York. The floor had already been measured extensively. When asked if he would come and measure it again, Mal said he’d rather not. Instead, he’d bring in a TMD and demonstrate that we could resolve the problem.
“When others proposed nothing more than academic theories and impractical solutions, Mal came up with practical approaches to what were often sticky situations,” Manny said. “Mal’s genius with tuned mass dampers enabled him to tame forced vibrations in many long span floors and wind induced vibrations in many of our tall buildings.”
Despite his self-reliance and resourcefulness, Mal had the remarkable ability to recognize skill in others and to marshal those skills around a project. He respected other people’s opinions, truly listened to their ideas and carefully considered the information and insight they offered. We were working on the Chifley TMD and had been in Australia for several weeks. One morning over breakfast, we were talking about the TMD and its characteristics. We began to gain an entirely new understanding of how TMDs work, so, I told Mal I would meet him on the site and that I had to go buy a metronome. “Hmm,” Mal said. “I’ll meet you there and I’m sure at that time you’ll explain to me just exactly why we need a metronome.”
Mal in the North Sydney office of Flack+Kurtz Australia in early 1994 while working on the Chifley Tower TMD. Photo courtesy Hans Jensen.
I got to know Mal quite well during those often long TMD project trips. He was always so knowledgeable on any subject, always interested to discuss and learn, and always ready to lend a helping hand. “I will never forget the time when we had a shortage of flu vaccines in the US, and my wife, being in a high-risk category, needed to find one urgently,” Manny Velivasakis said. “I had asked Mal if he could send me one from Toronto. Without any hesitation, he sent me the flu vaccine in a cooler with one of his sons, who was studying then at Columbia. He had even volunteered to have his medical doctor wife administer it, if necessary.”
For Soldier Field in Chicago, Mal worked with Thornton Tomasetti on a system of 21 TMDs that were placed at the raker ends.
Mal was always totally behind his team. Once during a meeting discussing TMD construction, a contractor made reference to how our submission would be viewed by the design team. But his words were architectural terms used in the context of the contract documents, which had serious implications for our work. I thought the contractor was slyly trying to make us responsible for a large portion of his work and I said “no.” I saw Mal look at me quizzically. I just had to glance back, and Mal knew that there was something going on here, what exactly he wasn’t sure of, but he still backed me up. Mal always had your back.
With Mal, you knew exactly what he meant and where you stood. He would explain his thoughts and calculations with sincerity and confidence in what he was saying. And yet, Mal allowed that he could be wrong. What a wonderful person to work with.
It seemed that the source of Mal’s confidence was his remarkable ability to reason and deduce his way to the correct answer to a problem. He would work through it slowly and carefully, considering every possibility. It often took him longer to come to the same conclusion as others, but many times, he found something else that was important and it changed the way the rest of us saw the problem.
Mal was extremely determined to find the right answer to any question, engineering or otherwise. He was extremely skeptical of other methods of problem solving, particularly computers, and preferred to rely on own reasoning and mathematics skills. Flying to Australia once, I saw Mal study our itinerary for 45 minutes, then announced the flight duration was 12 hours 10 min. He’d taken the departure and arrival times, corrected for time zones, international dateline and daylight savings, all in his head. We checked the airline’s flight information, which showed the same flight duration. Mal seemed pleased the airline agreed with him.
A model of the Chifley Tower tuned mass damper. Mal’s design consisted of a 400-metric-ton steel block suspended from the top of the building and connected to a hydraulically damped gravity system.
“My lasting memory of Mal is of a focused, calm, innovative, talented and highly intelligent engineer, who doubled up as a loving family man,” Hans Jensen said. “I am very privileged to be able to say that I was a friend of Mal Sacks.”
Mal leaves behind his wife, Diane, and three children, their spouses and families.
“If you knew Mal, you knew that there was a kind of tacit genuineness and consideration in his quiet presence,” said his daughter, Robin, at Mal’s memorial service. “Nothing at all about dad was superficial. Everything he did – from windsurfing and eating healthy, playing piano and to packing the car for a trip – was done with great sincerity, measured action, and based on principle. Dad did not use extra words. I remember knowing, even as a young girl, that if my dad was speaking it was either going to be funny or intelligent, usually both.”
Anyone who knew Mal, myself very much included, would absolutely agree.
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