CONSTRUCTING JOURNAL WEEK 7 This week’s focus was on spanning and enclosing space which covered over the main topic of roofs and all the structural elements involved in constructing a roof. This was indeed a great help in having a better understanding of visualizing and planning the design of my roof basically giving a clearer idea of what I should expect with the roof I have chosen to make which is called a combination roof. I also went to Rebecca for help this week partly because I couldn’t get my account and I had a few doubts of how I should work the software with the roof type I have chosen such as the numeric values that we have to put in the software to obtain the specified distances of the structural elements supporting the roof. One of the terms I did not quite understand on the software was the difference between “double span rafter” and “single span rafter”- why these terms didn’t occur familiar to me was because in the modules learnt, we were taught of continuous span which was why a double span rafter is considered much stiffer because it experiences lesser deflection than that is what is experienced by a single span rafter. These were very helpful notes to help me further write the report for the spanman project. The three main concepts that required to be fully studied when planning out the roof structure are ridge beams, rafters, roof beams and overhang. I was also confused on how to make the roof I’ve chosen because it consists of three different inclinations which is the base of it and then an inclination being the second structure and another inclined structure behaving as a triangle at the tier of the whole structure so I was explained that I had to do detailed planning by drawing out my structure and having a clear idea of what structures I wanted to include and that my roof followed the model of a gambrel and hip roof. This discussion with Rebecca put forth a clear picture of what needs to be done at least as the first step in using and going about the software. This week’s readings were quite interesting because I learnt new terms such as ribs or corrugation which is cladding/sheeting and I had one doubt if purlins are the same as batons as they both run perpendicular to rafters. This chapter really helped to understand the difference in spanning, spacing and overhang as well as other technical terms involved with a roof structure. In this week’s tutorial, we had gone on a site visit to tip top by a construction company.
The original facades are maintained from the existing construction which was horse stables. On the other side of this building is an office building of the 1920s facade. This project consists of 6 buildings, 411 apartments and various other buildings for different purposes. Feature panels on site are made to look as leaves of a corn cob- this is a bio inspiration. The site is totally 11000 square meters with a two level basement. 4000 loads of soil were removed. Two tower cranes and 15 different contractors on site.The structure is a light weight structure which is post tension. Precast and the next deck is formed and before doing so exist the ground slabs and then the hedge frames and then the tables on and lastly insert the bondex.
The above images are the structural supports of the ceilings which are held up by piers with bracing among one another to span over a larger area to support the ceiling.
The structure above, in the first level, it uses light weight timber floor which proceeds to level two and then the roof of the building. Level three is yet to be poured. Formwork is placed along with I-beams. All the buildings being constructed have in-situ which is concrete placed on site and since concrete is generally a very heavy material, many in-situ columns and pads. This material presented on the left is used in formwork. It interlocks and behaves as a roof sheet.
The material displayed on the left is a ‘rib’ which is used in reinforced concrete.
The image on the right displays the formation of the floor/ceiling level prior to the ground floor.
Bar caps are used to make a box over the bars and prevents it from falling onto the bars. A lot of tension is present at the top of the support and then loads are taken in mid-span to reduce the shear force present in the structural members supporting the larger structures.
The silver line that is stretching in the photo present on the left is post-tensioning where a large infinite dead end is present and at the end, ‘onions’ are placed which is presented in the image below. The strands present inside the silver lining material that extends has specific sizes and compress the strand and have lacing called onions with bars. The beams tension the strand as it becomes tight. Concrete is then placed one the framework is complete. The bondex present behaves as rib which is steel and is lighter and less costly.
This is the formwork of the deck which are the stairs made of concrete and steel based outline. The framework is clearly visiblethe structural supports of the layering of the stairs.
Props are used to support the masonry brick structure which is the main constituent of the building aside of it.
Piling rig is present which is the concrete section behind the pipes that carry the rain water falling on the site to prevent flooding of the basement or the surrounding areas of the site. It has circular casting which is grounded and pulled apart. It is high in tension.
The experience on site was indeed very informative and I was able to spot a few of the structural members come across in the theory learnt so far. I am looking forward to more site visits!