STRENGHTENING OF LOAD-BEARING ELEMENTS

The "Renovate" team offers a wide range of activities covering the inspection, strengthening, restoration and reconstruction of existing buildings.

In the following lines you will learn the most basic information about the problems of various structural elements: column, wall, slab, foundations, wooden beams and roof.

Reinforcement of vertical load-bearing elements - columns, walls and washers

The main function of the supporting columns, walls and washers is to take vertical and horizontal loads from the structure. These loads are collected in height and taken to the foundations of the building. The main requirement for the vertical elements is that they do not lose load-bearing capacity under extreme (maximum) loads such as strong winds, heavy snow cover and earthquakes. Loss of load-bearing capacity could lead to partial or complete destruction of the structure! The formation of "soft" areas / joints / in "pressed" columns is completely unacceptable and would lead to severe accidents.

A visual sign of weak areas and the need for reinforcement in columns or load-bearing walls is the presence of hair (sloping) or vertical cracks. When finding such, consultation with an expert is mandatory! In some cases, a more detailed inspection of the element or the whole structure is required before the reinforcement works. Bare and corroded reinforcement in columns or washers also threatens the security of any building and special attention should be paid to time. Their cosmetic concealment, especially with gypsum solutions, is unacceptable and dangerous!

A special case in practice are the frame structures, the vertical elements of which are extended outside the structure. Such elements do not take serious vertical effort. Owners often neglect the condition of these elements, omitting the fact that the behavior of the building in the event of an earthquake depends on them.
There are many proven methods for strengthening load-bearing vertical elements depending on the desired end effect - increasing vertical or horizontal load-bearing capacity, ductility and others.


The classic methods of reinforcement can be defined as the framing of columns with a steel skeleton or a reinforced concrete casing.

More modern and cost-effective reinforcement systems are based on composite systems. They have a number of advantages over conventional ones. Choosing the right system to increase the reliability of buildings is a complex task depending on a number of factors specific to each site.

The choice of a reliable and cost-effective amplification system requires sufficient information about the construction of the building. For this purpose, we at "Renovate" offer the service "Investigation and Diagnosis“ for all types of constructions.

Additional reinforcement of reinforced concrete horizontal elements

The most common case of cracks forming in the slabs is occures immediately after their deformation due to unacceptable slack. The reason for cracking in this case may be the lack of necessary formwork support to carry the minimumamount of required strength of the concrete.Could as well be its lower strength performance or perhaps incorrectly placed or wrongly constructed steel reinforcement. All of these scenarios are common in old house built dating back to the middle of the last century. Typically, these types of cracks do not increase their size during the lifetime of the structure. If the floor slack is greater than the allowable, measures should be taken to bring it into a design state that guarantees safety exploitation in the future.

There are innovative, elegant reinforcing systems that allow straightening corrections in already built reinforced concrete slabs within 24 ÷ 48 hours without the presence of „wet“ processes. Cracking of the slab can also occur as a result of the concrete curing after application. These cracks must be closed by a cement plaster to protect reinforcement and concrete from external influences. This is especially true for rooms with high humidity or aggressive agents in their environment, where dense filling of the cracks is absolutely necessary as soon as they occur.

Inaccessible slacks are also observed in beam elements. In addition to the above-mentioned causes, the corrosion at the lower section of the beam significantly reduces its vertical load bending and shears capacity.

Reinforcement of wooden and metal elements

Wooden beams, columns, capitals and others can be seen both in the oldest houses and in modern architectural solutions in new buildings. Their aesthetic value is high and their preservation in the original during restoration is becoming a challenge. A classic method of repairing wooden load-bearing elements in our construction practice is to combine them with metallic elements that take up all or part of the load. A major disadvantage of this solution is the addition of visible metal elements that do not always fit into the overall appearance.

Foreign scientific research show the possibilities for symbiosis between one of the oldest building materials - wood and modern composite materials - fiberglass, carbon and others. Unlike classical approaches, the use of composite systems allows minimal interventions on the original wooden elements. Their extremely high mechanical properties reduce their size, which makes it possible their unnoticed addition  to the original construction.

Repair of roof construction

According to Bulgarian National Statistical Institute there are 973 652 semi-solid buildings with brick walls and floor slabs built on beamwork. Most of them need major overhaul of the wooden beams and their connections to the brick walls of the building. The main objectives of such a repair are to observe the aesthetic appearance of the beamwork, to replace or reinforce the affected beams and, above all, to increase the seismic resistance of the building. Wooden floor is the weakest place in taking seismic impacts. In their original form, they do not have enough stiffness to properly redistribute horizontal loads on the vertical load-bearing elements. This leads to overloading the columns and is a prerequisite for serious consequences for the building and its occupants. Luckily, there are a number of foreign norms that address this problem and offer tried and tested solutions that are applicable to our building practice.

The observation is separated on the wall in the direction of the street or the courtyards. There is a real danger of destruction with potential material damage and endangering the life and health of lives and accidental passing. Namely roofing and under-roof spaces with the most dangerous even in moderate earthquakes

You can read more about the dangers of an earthquake here. "Renovate" offers inspections by a construction engineer and design solutions for strengthening wooden roofs.

Strengthening of beamwork

According to NSI statistics, there are 973,652 semi-massive buildings in the country with brick walls and floor slabs built on wooden beams. Many of them need major repairs to the load-bearing wooden beams and their connections to the brick load-bearing walls of the building. The main goals of such a repair are to preserve the aesthetic appearance of the joists, replacement or strengthening of the affected beams and most importantly ̶ increase the seismic resistance of the building. Wooden floor structures are the weakest point in absorbing seismic impacts.In their original form, they do not have sufficient rigidity to properly redistribute horizontal loads on vertical load-bearing elements. This leads to overloading of the columns and is a prerequisite for serious consequences for the building and its occupants.

Fortunately, there are a number of foreign norms that treat this problem and offer proven constructive solutions for strengthening of beamwork. They are reliably applicable for the Bulgarian construction practice. Our team offers design and implementation of various types of reinforcement systems for joists, depending on the specifics of the building, its condition and the budget for repairs.

In addition to such structural repairs can be provided and increase the heat and sound insulation properties of the beamwork.

Foundations strengthening

The foundations are the lowest positioned building elements in a building. Their function is the transmission of loads from the top of the structure onto the soil – the earth’s foundation. Nowadays most of them are made of reinforced concrete, but in older buildings there are concrete, rubble concrete, masonry with natural stones or clay bricks, wood, metal and others. Depending on the depth of foundation, they are shallow or deeply laid. Shallow foundations can be made in depths of as little as 1m, while deep foundations can be made at depths of 20 – 65m. Shallow foundations are used for small, light buildings, while deep ones are for large, heavy buildings. According to their geometrical features, the shallow piles are individual footings, strip footings, raft foundations or combination. The deep foundations are in the form of piles, diaphragm walls and borehole foundations. The most common reason for cracks appearing on the walls of buildings is the uneven sinking of the foundations. The reasons for it can be varied in relation to the natural and manmade processes in the soil around and under the building. In addition to cosmetic defects, the sinking of the foundations leads to increasing the stresses in the elements of the building which reduces bearing capacity.

Determining the agents and expedience on their removal is subject to a thorough techno-economic analysis. In any case the first step is consultation with an expert in the field and postponing this step can lead to more expensive repairs and extremely unwanted consequences.

Reinforcement of masonry structures

A common occurrence in old houses is the complete renovation – inside and out. The main goal of the owner is to use the already constructed supporting structure of the building. In a number of cases, even at initial inspection, defects in buildings were observed, such as highly developed cracks in bearing brick walls, uneven sinking of foundations and others. These defects are a clear sign of partial or total depletion of earthquake resistance, which actually threatens the lives of the inhabitants. Reconstructions should be carefully considered with regards to the age of the masonry, the planned changes that would involve new openings in the walls, the obsolete ways of construction and the calculation of the buildings at past times. Regarding to the state of the existing construction, measures may be necessary to strengthen it, in particular, to increase the seismic stability.

An entire reconstruction and repair is an expensive and complex task to conduct from scratch ,which would be meaningless if not carried out in a proper way If done negligently i na few years it would have to be repaired due to later defects and shortcomings in the old structure of the house. Consultation with an expert at the preparation of the project stage is a necessary part of the repair in order to guaranteeing the safety, long life and profitability of the entire construction project.

Injection of joints and cracks in buildings and swimming pools

Resins and mortar injection are applied as an alternative to well-known foils, membrane plasters and other waterproofing. The injected waterproofing solutions are particularly effective in the local appearance of moisture or leakage in wall or floor elements and especially in the connection between them. Its main advantages are the water tightness created throughout the section, the corrosion protection of the reinforcement, the rapid execution without the need for chiseling, the deformability after bonding, the long service life of the injected polyurethane resins (as the life of the building), while the polyurethane does not damage the environment and the individual. More about solving the problem of moisture in the underground parts of the building can be found Here.

 

In addition to such structural repairs can be provided and increase the heat and sound insulation properties of the beamwork.

 

New door and window openings

In recent years, people's lives are changing at an extraordinary pace. New appliances, various furniture schemes, modern architectural solutions are entering en masse. All this must successfully fit into our old houses or condominiums built in a bygone era. The small windows in the old houses, the lack of direct connection between the rooms or to the yard, severely limit the ergonomics of our home.

Fortunately, reconstruction involving the slaughter and opening of bright spaces for a door or window is entirely possible. At least in most cases. Even when the opening is located in a load-bearing brick or reinforced concrete wall. This, of course, can only be done with an approved project prepared by a design engineer with experience in the field of redevelopment repairs. It is a mandatory condition that he is well acquainted with the work of different types of reinforced concrete and masonry / brick structures. Our team has extensive experience and offers both design and execution of repair work.