Risk of structural adequacy due to renovations of old buildings without any inspection

According to experts, commercial renovations of old buildings that are carried out without prior structural adequacy checks (!) are like bombs waiting to explode. Those who are aware of the problem tend to describe it in seven words: “Our hearts tremble when we see such indifference…” However, the biblical destruction caused by the recent earthquake in Turkey and Syria, as well as the increase in seismic activity observed in recent months in Greece, has prompted many openly refer to the problem and the dangers posed by uncontrolled upgrades/renovations…

– Advertisement –
Civiltech
Dimitris Kapsimalis, president of the Union and Federation of Greek Building Contractors, speaking to “NEA,” says it clearly: “Stop renovations unless structural adequacy checks are first carried out on apartment buildings constructed before 1959, as well as on most buildings constructed before 1984.”

The question arises: How did this problem arise? “In recent years, entire buildings (apartment blocks), mainly by foreign investors, either built before 1959 or in the 1960s and 1970s, have been purchased, radically renovated, and then leased or sold,” points out Konstantinos Kanellopoulos, secretary general of the Federation of Greek Building Contractors and a civil engineer.

Unsupervised work
– Advertisement –
Fronius
As he says, “unfortunately, the work carried out on most of these buildings, although involving radical renovations, it is carried out without supervision and control of structural adequacy by an engineer, since the new owners, in order to achieve low costs, do not even proceed with the issuance of even the minimum required approvals for small-scale construction work.”

According to Konstantinos Kanellopoulos, “in all these buildings, a large number of internal walls are being removed, the layout is being changed, and the static loads of the floors are being modified.

In addition, interventions are often made to their building structure, with holes being drilled in their slabs and beams for modifications or additions of staircases, modifications to their entire stairwell, their balconies, and the passageways of their electrical and mechanical installations.

I am interested in window framesI am interested in window frames
Also, according to him, many rooftops are undergoing changes in use, with auxiliary spaces being converted into main spaces and entire terraces being planted and various structures added (pergolas, shelters, barbecues and ovens, built-in benches, and even hot tubs) are being added, adding uncontrolled static loads to these old buildings, thus jeopardizing their static and seismic resistance.

Attention to seismic safety
“For many years now, we have been pointing out that any intervention in old buildings must be carried out with great care, following a specific study and with particular diligence,” emphasizes, among other things, Panagiotis Karydis, academic, member of the European Academy of Sciences and Arts, and professor emeritus at the National Technical University of Athens.

” This is because, in the past, vertical expansion (by adding floors) and/or expansion of the floor plan in old buildings had begun, and the state subsequently granted the possibility of increasing the land use coefficients .”

As he points out, however, relatively recently there has been significant construction activity aimed at upgrading older, even multi-story buildings for commercial use, such as short-term rentals or conversion into office buildings, etc.

In this case, we distinguish between two categories of multi-story buildings in which such interventions are carried out:

A) The first and most numerous category is that of old apartment buildings, which are mainly located in the old traditional centers of residential areas. The period of construction we are referring to is before 1985, during which 78% of our country’s building stock was rebuilt. During this period, i.e. before the first Greek Anti-Seismic Regulation (which came into force in 1959), 30% of the country’s building stock was built, and between 1959 and 1985, 48% was built.

The period (1959–1985) coincided with the rapid development of the country and the consequent rapid construction of apartment buildings using the quid pro quo system. They were constructed using reinforced concrete frames with columns at relatively short distances from each other and brick partition walls.

According to Panagiotis Karydis, during the first 10-15 years of this period, as well as the previous period (before 1959), even more so, these brick structures were sturdy, fairly dense, well-built with strong bricks by skilled and experienced craftsmen.

The loads are multiplied
B) The second category refers to even older buildings made of masonry and with wooden floors. “In these buildings too, modern interventions for the same reasons mentioned above are often just as brutal and dangerous if they are not carried out after a special study and particularly careful execution,” he continues.

Why? Because, among other things, the loads on each floor are multiplied. Furthermore, with regard to wooden floors, the demolition of partition walls destroys the floor supports that have been in place for decades, as well as the positions where permanent loads are imposed by the walls of the floor itself. This disrupts the existing support and stability of the floor, creating mobility and significantly reducing the beneficial function it provided to the building in coping with seismic loads.

Seismic protection shield
“The masonry walls contributed significantly to the seismic behavior of the respective structures. They constituted the first seismic protection shield, as they were continuous up to the ground floor – foundations.

I believe that even though the frame was calculated using significantly reduced seismic coefficients (compared to those in force today), precisely because of the existence of these walls, the seismic behavior of apartment buildings from that period proved to be quite satisfactory,” he adds.

“Even a non-specialist can easily understand that if we remove these walls and do not replace them with suitable elements that provide the corresponding rigidity and strength (something I have reservations about whether it can be implemented everywhere), we will decimate the existing level of seismic protection,” continues the academic, member of the European Academy of Sciences and Arts and professor emeritus at the National Technical University of Athens.

He adds: “A similar problem exists, if not worse, when wall structures are demolished in the same way only on an intermediate floor. This creates a phenomenon of discontinuity in the vertical rigidity of the building. This discontinuity is harmful both to the building itself and to its neighbors, which were then built in full contact with each other.”

Covering buildings
According to Panagiotis Karydis, in addition to this, for aesthetic or even practical reasons, the load-bearing elements of the building, such as beams and columns, are covered with cladding without first being properly repaired or maintained, regardless of their structural condition (e.g., whether their reinforcement is corroded or whether there are cracks).

Where does the problem lie? “With these investments, which are generally flexible, it is not possible for any condition (cracking, corrosion, etc.) to appear on their visible surface,” he argues.

Higher costs in the event of an earthquake
“The costs of pre-earthquake reinforcement are lower for society than the total economic impact of an earthquake disaster that may occur many years later,” says Theodosis Tasios, professor emeritus at the National Technical University of Athens (NTUA), speaking to “NEA.”

As he says, there should be co-financing for these expenses. Why? Because, as he says, the state will in any case spend unbearable amounts in the future following a possible seismic disaster.

What needs to be done…
According to Panagiotis Karydis, two things need to be done: First, before any such intervention is carried out on a building constructed before 1985, a seismic adequacy study with a complete structural survey must be carried out, and second, the possibility of constructing appropriate stiffness and strength elements in the piles of apartment buildings should be provided where this is proven to be necessary following a special study. These elements should be designed and constructed in such a way that they are limited to the space of the pile and, where applicable, the corresponding basement, if there is one.

Prokopis Giogakas