Expertise · PT Arah Rancang Mulia
Benjamin Sarengat is President Director at PT Arah Rancang Mulia in Indonesia, and treats quality and cost as one decision rather than two. Precision matters to him when it serves a purpose, and fluency with software never replaces the engineer's own judgment. That principle runs through the story below.
In Benjamin Sarengat's own words.
"The tool gives us the number, but the engineer chooses the basis."
I learned this on my experience when designing an SRC (Steel-Reinforced Concrete Composite) building. Midas Gen designs an SRC column on an allowable-stress basis, while Design+ checks the same column to AISC 360-22 LRFD. Two different answers for one column, and both of them correct inside their own framework. No software can tell you which one is suitable for your project. It needs an engineering decision.
For years I lived with a tension I could not resolve: how thoroughly I wanted to check a design, against the deadline the owner had already fixed. Safety was never the variable, but the number of load cases, member groups and what-if scenarios I could open by hand in the time available certainly was, and I was never comfortable with that.
What changed it was automation. By driving Midas Gen NX through its API, the checks that used to compete with the schedule now run as a batch. Coverage stopped being something I had to ration. So the question I ask before an analysis is no longer "what can I afford to check?" but "which result will actually change the drawing?" The first question was a compromise; the second one is engineering. That is what turns a calculation into a recommendation the owner can act on.
It happened while I was designing a column in a special moment frame to ACI 318M-25. When we ran the automated ductile design routine, the required longitudinal reinforcement came out at 3.00 per cent, the reinforcement ceiling for the section. The bar congestion that implied was what made me look again.
I rechecked the column in a web application our office built for these calculations, and two things came out. First, the moment governing the column was not the moment from the load combinations. It was a capacity-design moment derived from the beams. Second, that moment was then compared against a reduced column strength using phi = 0.65, even though the code clause it comes from compares nominal strengths on both sides.
Sized from the load combinations, and with that clause applied as written, 2.11 per cent satisfies the PMM demand and the ductile design requirement together. So we kept the engineer's arrangement instead of the imposed one. We have written the full derivation up and sent it to the software's engineering team, and their representative has been open to the question from the start. I am glad to be checked on it.
Q. At the HAKI 2026 seminar, the slide you remember was the plainest one you had written. Why that one?
The slide said: engineers are never satisfied, and that is not a weakness. It is simply how our profession works.
No matter how good a graphical interface is, engineers will eventually look for a workflow that fits their own office better. Every firm has its own habits, templates, and sequence of checks, and no vendor can anticipate all of them. That is why the API mattered to me, and why I wanted our community to hear about it. Opening the API was a decision to trust the engineer. It said: here is the engine, now build the workflow you actually need.
For our office, that changed the work itself. Checks that used to compete with deadlines can now run in batches, and the verification tools we built on top of it are truly ours. In the days that followed, we reached out to several HAKI participants, and many said the API design features were compelling to them. That was the day the software stopped being something I simply used and became something I could build with.
We are grateful to Benjamin Sarengat for sending the full derivation to the software's engineering team and inviting the check. Software extends an engineer's reach, and an engineer who goes back to the clause behind a number helps make that software better for everyone who uses it.