Durban - What fell first? This is the question engineers are grappling with as they determine the trigger that caused the partial collapse of the Tongaat mall in November, in which two people died.
A commission of inquiry led by the Labour Department has been set up to determine if negligence led to the collapse.
A beam, referred to as beam 7, and two columns, called 243 and 319, have been identified as being the three possible causes, but engineers are at odds over what fell first.
Engineer Ed Weakley, who was contracted by mall engineer Andre Ballack’s law firm to investigate the collapse and is also acting for Ballack’s insurance firm, testified on Thursday that he believed beam 7 failed first.
Identifying the trigger of the collapse will be crucial as it could lead to the conclusion that either Ballack or construction company Gralio Precast was at fault.
The R208-million mall was being developed by Rectangle Property Investments, whose sole director is businessman Jay Singh’s son Ravi Jagada-san. Gralio Precast lists Jagadasan and his stepmother Shireen Annamalay as directors.
The commission heard earlier that the project had no approved plans and there were high court orders granted to stop the construction before the collapse.
Weakley said the beam was the “weakest link” because it was designed to be a continuous structure, but it was constructed with a cold joint - something created when concrete is poured in two batches.
“The beam cannot behave as it was designed to and would have split apart at the point of weakness, which is the joint,” Weakley said.
He also said the beam had inadequate steel reinforcing, with seven, not 19, bars.
Weakley said columns “319” and “243” both had structural and design concerns.
Weakley said there was a foundational weakness in 319 and low concrete strength in 243.
Under cross-examination by commissioner Phumudzo Maphaha, he said column 243 was not designed to carry the required load, or weight, unless adequately “braced”. Bracing refers to propping or support given to prevent sideways movement.
There was a dispute between the engineers over whether the columns were braced on the mall.
Asked what he would have done differently, Weakley said he would have increased the size of column 243 if it was unbraced.
Maphaha also said Weakley’s conclusion that beam 7 was the trigger appeared to be supported by site foreman Ronnie Pillay’s statement.
“Pillay said the collapse was coming towards him, which would suggest that it was coming from beam 7.”
Advocate Ian Topping, acting for the eThekwini Municipality, said engineer Gons Poonan, who investigated the collapse for the city, concluded the cave-in had started with column 243.
Weakley said he did not know where the collapse started, but in his view it was the beam and not the column.
Gralio’s advocate, Saleem Khan, asked Weakley if Ballack had been negligent in his structural design.
Weakley replied that Ballack did not have the “correct design load” for column 243.
During re-examination by Ballack’s attorney Richard Hoal, Weakley clarified that column 243 might have supported the load if it was braced, but was more likely to fall if unbraced.
Meanwhile, the Labour Department is expected to send out a more stringent prohibition notice to prevent security guards on the site from walking near the building after an inspection on Tuesday revealed it appeared to be unstable and could collapse further.
The commission continues on Friday.