Structural Design for External Lift for Ministry of Mass media

 This is a steel lift structure designed for the main building at the entrance of Ministry of Mass Media. Still under construction. Lift pit was made out of concrete with 4 350mmx350mm L cross sectioned columns at the four ends. A brick wall was used as the permanent shuttering for the lift pit construction and the brick surface was water proofed. Above ground level 200x200 I section steel columns was used as this is separated from the building and considerably a slender structure. 

Two Storey House in Bolawalana Road, Negombo.

The architect of this project is Amila Ruwan Liyanapathirana and the structural design was done by Isuru S. Amarasena.

The site is located in Negombo area and the common soil nature in that area is a sandy soil with a high water table. The soil is inspected using two test pits. Since this sandy soil was very much good enough for bearing the loads, the only thing proposed was to stabilize the soil using a poker vibrator before placing the screed concrete. As the water table was so high a continuous water pumping method was used before placing the screed and the structural concrete. 

The site before the constructions was seen as below.

 

Below you can see the structural model prepared for the proposed housing unit. 

Below you can see the different floor elements with three different colors. 

In the below image you can see the Reinforced concrete members in the red color and the steel sections in the green color.

Beams are to be designed for flexure and shear mainly. Below you can see the bending moment diagrams of Beams. Inorder to withstand for the flexure we have to provide adequate reinforcements and member sizes for the beam elements at appropriate places. You can see some larger values in some places. So when you don't have load bearing brick walls under the beams and when you have a moment larger than 22kNm, only you or your masons can't decide the required reinforcement amount and the required size. So you have to go for a real analysis and a real calculation with a help of a structural engineer. Then you can have the most optimized but stable solution for your structural elements. If you don't go for a structural engineer, what mason or the contractor do is, he will provide a large number of reinforcement bars with a huge sized beams. That will end up with wasting your money as well as the structure will be sometimes unsafe. Because if you provide more than the required maximum reinforcement amount, it will lead to a fail of the structure without eve giving you sign of failure. So this is critical and alsways try to go for a structural engineer.

A Pad foundations with 9x9 tie beams and  rubble walls was proposed for the substructure. Shown below are some of images taken during the foundation constriction stage. 

 Below you can see a few of our structural drawings provided for the constructions of the house.

The structural drawings are given with all the required and essential details in a state that very easy to read and understand the contents. Even the client or an ordinary worker can understand the things in it. Because the simplicity should be there as the drawings to be read by simple workers or masons most of the time. When you follow the structural engineers guidelines and the instructions you can finally end up with a solid, stable and also an economical construction. It will be a very relief to you and your mind as you are going to live under that roof for your entire lifetime. 

 

Generator Building for Provincial General Hospital, Badulla (4 Story)

The ground floor is designed for generator rooms. And the above floors are designed to be used as male staff accommodations. The building is being building in the premises of Provincial General Hospital, Badulla. Some beams had 12m larger spans and it was designed without having any disturbing columns inside the building in order to use the entire space at once. All the columns were placed along the perimeter line. The column beam fixity also was considered to the calculations. This project is under constructions. 

The gunny bags shown here are used to cure the column concretes by wetting them during the 

 

Structural design of a Massive housing unit in Colombo

 We did  the structural design of this massive housing unit to be built in Colombo. Structural modal was done using the csi etabs software. Below you can see the analyzed stresses on the slab elements of the building.

Below is the column layout drawing provided by us for the construction.

Below you can see the reinforcement drawing of the columns. It shows the reinforcement steel bar diameter and the diameter of the stirrups and spacing's as well. It also shows the the levels and the existence of the column at each level.

Below you can see the structural modal with the proposed element sizes at the initial design stage.

Structural Design for twin houses in Boralesgamuwa

This elegant twin luxury houses near Katuwawala, Boralesgamuwa was designed by MC&C Architects and the client was MG Homes.  The structural design was done by Chartered Structural Engineer, Isuru S. Amarasena.  Initially the the soil investigation was carried out and came to know that a little silty sandy soil was available under 3 feet of the existing ground level. According to the soil condition a little soil improvement was proposed and and carried out. 

These photos were taken during the construction stage. 

Below you can see the deformed shape of the building when the preferable loads applied on the structure. It clearly shows the deflected shapes and the structural engineer ensured maintaining the deflections in the allowable range in-order to provide a better serviceability requirements.

Below images shows the service loads acted on the foundation coming from through the columns from the superstructure above. By considering the existed soil condition and the provided soil improvements, structural engineer designed pad foundation sizes, reinforcements and the rubble foundation and tie beam system. These analysis for calculating the footing loads is essential for providing the economical footing sizes. It ensures the required additional strength for the heavily loaded footings and also it saves the clients money by choosing the small sizes and reinforcements for the slightly loaded footings.

Below image shows the axial forces acting on the columns of the house. The reinforcement requirement of the columns is governing by two factors, Axial forces and the bending moments. Structural engineer does the analysis for finding the governing factor for each column and selecting the required reinforcement by avoiding providing much larger reinforcements for all the columns.

Below diagram shows the bending moments induced in the beams. It is required to provide adequate reinforcement to withstand the acting larger moments in those relevant places in-order to avoid the cracks and deflections. and also in the column beam junctions the beams are required additional reinforcements for the top layer as they have more hogging moments. These things were well managed and the structural drawings were prepared by the structural engineer. It saved clients money and time and also ensured the required stability and strength of the structure.

Below you can see the stresses induced on the slabs.

When you have a house or building, in-order to avoid the settlements, cracks and to save your money and also in-order to ensure the stability of the structure please consult a professional chartered engineer and get done a structural analysis and have some structural drawings prior to the construction stage. Otherwise lot of problems may occur during and after the construction stage which will lead to huge money losses. Be wise and be happy. Thank You!

 

Elegant House Design at Pannipitiya

 This elegant house's architectural design is done by the architect, Chathura Perera. His designs have unique features but arranged in a simple grid system which leads for economical beam designs. If the house or building has simple square based continuous grid system it will be able to used parallel continuous equal span beams and they usually have smaller beam depths and minimum reinforcement areas which leads to lower the material and construction costs. Actually architecture is not a word for unique building elements which used a very difficult construction methods with a higher cost. It is a science of having the required utilities with a minimum cost and contains an elegant appearance. This thing is nicely handled by Architect Chathura Perera and Hats off for him and his designs. 
The house is constructed near pannipitiya and very close to Devram Viharaya. The Structural design is done by Chartered Structural Engineer, Isuru S. Amarasena. He is working as a Senior Design Engineer (Structural) in the Structural design section of Central Engineering Consultancy Bureau. 

The substructure is having some pad foundations with 3ftx3ft and 3.5ftx3.5ft sizes. All the foundations are connected with tie beams. The loose soil part was found during the excavation of foundations and it was filled and compacted with quarry dust for a better bearing capacity and to avoid the differential settlements. 
This unique project is now almost completed and very few small small things are remaining. See It has an elegant look at night for lights. Thanks to the experienced contractor who didn't ruin the design and gave the nice finish and same sight as in the 3d modal. 

House of an Electrical Engineer in Hokandara

This two story housing unit was proposed to build in Hokandara area near Colombo. The Architectural Design was done by Mr:Chathura Perera. The total land area is 9.8 Perches and the total floor area of the house is 3060 square feet. The ground floor is consisted with a single car parking slot and the side road with the dead end could be used for additional ceremonial parking. 
In the ground floor 1 bed room with attached bathroom, living room,  kitchen, servant's room and toilet are placed. The Architect has taken successful effort to have a more spacious look inside the house. So in the first floor he has designed like two reinforced concrete slab parts connected to each other by a small narrow timber deck which is supported on two Steel "I" beams. In the either sides of that small bridge type arrangement double height spaces were placed. In the first floor master bed room is placed with the nice look of the paddy fields through the side road. another two bed rooms are placed in the rear side of the house with a common bathroom.
    the top slab of the parking area has used as the first floor open terrace to the sky with a flower trough. The second floor terrace is used as the larger ceremonial open terrace area. Another third slab is placed to cover the stairs and it is proposed to utilize as the water tank slab.
        
    The structural design is done by Chartered Structural Engineer, Isuru S. Amarasena. He has visited the site initially and looked at the side conditions and the soil conditions. As a hard type kabok soil strata was identified through out the land under 2 feet from the existing soil 3x3, 3.5x3.5  sized pad footings could be used for the substructure. In order to compliance with the Robustness Criteria, 9x9 tie beams were prosed with T12 Diameter reinforcement bars with R6 stirrups at 125mm interval spacing. Rubble foundation with different sizes were proposed for different areas of the house according to the considerable level differences. One blind wall (Blind end) is faced to a existing boundary wall with a longer height of the neighboring land and special attention was given for that side. Separation of two structures and water tightness were taken in to account when designing them. In order to avoid the strap footings which needed a high attention and a high cost, the columns at the blind end are shifted towards the house inside the walls. So no, eccentric footings were used for the constructions. Below are few images taken during the foundation construction stage. 

Here you can see the pad foundation base pits with their reinforcement nets. The soil excavation is done in an effective way considering the required depths for the rubble wall foundation depths and tie beams. 

This image is taken after placing the rubble foundations. The column reinforcement has come out of the pad bases.