AWARD WINNING SEISMIC ENGINEERS

How Long Does Soft Story Retrofit Take?

 

Retrofitting is a process of modifying or renovating and other various construction work combinations of buildings, structures that had been manufactured before. So, how long does soft story retrofit take? - As long as retrofitting of buildings can include different types of construction works, the duration can not be determined, without preparation consultancy. You can learn more about retrofitting and soft - story retrofit in our previous article. However, on average a project can last from 4 to 12 weeks, after receiving a client's permits and plans, depending on the scope of work.


Retrofitting Process

A retrofitting process includes changing or improving the structure and system of a building, that may be employed with different categories and technologies. 
There are several common categories of building retrofit technologies, which provide three different types:

  • Demand-side management
  • Energy consumption pattern
  • Supply-side management

And the seismic retrofitting approaches to five building types:

  • Soft-story
  • Non-ductile concrete
  • Tilt-up
  • Steel moment frame
  • Unreinforced masonry

Almost no building can exactly be like another one. Technically, some buildings, at a first sight, may seem to be alike they must have their distinctive differences based on various factors, which may include structural materials and compositions, the tear and wear on the building, and often even the composition of the soil between the tear and wear.
It is impossible and non-professional to give a specification to a retrofit project without doing engineering studies that can examine both the builds and properties itself. 


Soft-story

Soft story structures are common among apartment buildings, which are characterized by open parking on the floor and dwellings above. There are some examples, the ground floor is used as a retail area and enclosed with windows, which does not have other structural supports.
In major seismic activities, those structures framed with wood are considered extremely vulnerable to collapse.

Retrofit construction for this kind of buildings usually entails the installation of steel moment frames or other frames that are set in sturdy foundations, to absorb seismic ground motion and prevent sway.

Non-Ductile Concrete

Non-ductile concrete structures that are built before 1978 are buildings that have concrete roofs and floors supported with concrete walls, frames, and columns. Because of the limited capacity to absorb the energy of strong ground shaking and stiff construction, these structures can easily collapse during an earthquake.
Non-ductile buildings are frequently used for retail or office, which is the reason for having a larger amount of death and injury during an earthquake, for these structures are drawing large numbers of people.

The guards against collapse from seismic activity, the construction of a non-ductile concrete building retrofit, in general, requires the use of column fortification and shear walls to provide stronger frameworks, that will be able to prevent a collapse of the heavy floors above.

Tilt-Up

Tilt-up constructions have begun in the early 1900s, yet they were not been caught on by in-time construction boom during the post-World War II period.
Tilt-up constructions have cost-effective techniques to pour the buildings' walls directly at the Jobsite, afterwords, tilting (raising) the panels has been started to be a common way to meet the demands of California's new commercial buildings.
The tilt-up concrete walls can weigh, on average 100.000 to 300.000 pounds.
Traditionally, tilt-up structures were a priority during the late 1970s, which were built with weak and limited connections, having been proven to fail in an earthquake. Due to the severe damages and collapses could be caused - so this kind of construction defects are easily fixed with tilt-up building seismic retrofitting. 

Steel Moment Frame

Another ancient building construction type is the steel moment frame, which dates past in the 1880s in Chicago, with the very first skyscraper, however, the buildings constructing strategy and the technique was more popularly used during the 1960-1990s.
Steel moment frame is unique with its use of fixed steel frames of beams, connected to columns, that are supporting a couple of floors on the structure.
Many of the steel moment frame buildings in Southern California uncover fissures and cracks in their frames and can likely be collapsed in a major earthquake.
Several retrofit approaches are considering in these cases, depending on the buildings. Some of them included beam-column connections which are boosted, and also chevron bracings in the structures different sections.

Unreinforced Masonry

Unreinforced masonry buildings create many of the older structures typical in the communities of downtown. They are characterized by many structures, such as cinder-blocks,  chimneys made of brick, and other masonry materials that are not braced with any reinforcing materials or masonry material. 
Unreinforced masonry structures are at a risk to collapse in an earthquake, because of a general failure of the mortar or when an allocated amount of the masonry, such as low retaining walls from the from of the building and fall on the sidewalk.


soft story retrofit 1990s

As we already mentioned, a soft story retrofit lasts depending on the types of retrofit, that was spoken about in the previous paragraphs.
If you do not have cripple walls, it may be done in one day, if you have standard cripple walls retrofit, the service should be delivered the first day, normally doing all the bolting works, shear and framing transfer tie installation, in general, are employed the next day, and the third day - the plywood.
When there is a need to work in the living area where there might be a lot of sheetrock and plaster, that require to be removed by the service, you can expect 4-5 days. 
In a word, soft-story retrofits literally can take 5 working days, without the other days between, unless building inspectors and ordered custom steel are ready, which sizes can be determined only once the labor gets stared. Besides all the concrete and he digging jobs need to be done before and hillside houses may take a few days, sometimes even weeks.
If you have Army Of builders take a look, we can give you a better idea at the time, and for more questions, you maybe have about retrofitting, feel free to check our FAQ article about earthquake retrofitting.