Engineering Architecture Planning

 Auther I Prof. Dr. Jahangir Alam I [email protected]

What is sustainable development?

Development should be such that it meets the needs of the present generation while maintaining the ability to meet the needs of future generations. Then it can be called sustainable development. Sustainable development should be disaster-tolerant, sustainable, environmentally friendly, self-reliant technology. For example, if Bangladesh’s infrastructural development, building construction is not designed to be earthquake-tolerant, then it cannot be called disaster-resilient development. The role of architects, planners and civil engineers is very important in building a modern, sustainable and developed Bangladesh. Sustainable development in Bangladesh is a challenging task. We must build a sustainable development system considering our problems, socio-economic status, etc. Through sustainable development, disaster risk should be reduced, disaster survival capacity should be increased. Environmental damage must be reduced through sustainable development. Development is not possible without building new structures. Construction means environmental pollution. This is because the production, transportation and installation of construction materials emit large amounts of greenhouse gases, which contribute to the warming of our only planet, climate change and environmental pollution. If a structure survives for 20 years, it must be built 5 times in 100 years. Conversely, if the building has survived for 100 years, it will have to be built once. Construction 5 times means 5 times more environmental pollution. So, there is no alternative to sustainable construction to reduce the damage to the environment, to protect the earth from pollution. In Bangladesh, buildings tilt without an earthquake, heartbreaking accidents like Rana Plaza happen. With this in mind, we need engineers, architects and planners to work together to combat natural disasters and promote sustainable development. There is no alternative to communication, exchange of views and cooperation among engineers, architects and planners for the infrastructural development of the country.

What is risk mitigation? (risk reduction)

Risk mitigation is any temporary or permanent action that reduces or eliminates the risk of loss of people and property. If the risk is low, the damage is less and there is a quick recovery from the disaster. As natural disasters become more and more dangerous and regular, risk mitigation activities lead a nation towards disaster resilience. To mitigate the risk, it is very important to assess the possibility of a disaster before it occurs. One of the pre-preparation tasks is to do a detailed engineering assessment of the existing structures and retrofitting (repair and strengthening). Another task of pre-preparation is to ensure proper design and construction in accordance with the building code or other codes to build new structures. In this case, the role of planners, architects, engineers, local governments are very important. Besides, the involvement of law enforcement cannot be excluded.

Architect’s Role

The utility of any establishment is needed as well as artistry, environmentally friendly, tradition, aesthetics, exception and creativity. Architects are the architects of all this. The architecture became unique with the touch of the architect. The architecture became unique with the touch of the architect. In designing all types of disaster-tolerant structures including earthquakes, architects also need to have some knowledge of civil engineering, which can take their design to the next height.

 The role of the planner or planner

Planners take into consideration the physical form of the environment, economic functions, future needs, environmental protection, state principles, basic human needs and social impact. With the input of architects and civil engineers with the work of the planner, it is possible to do disaster tolerant, livable, environmentally friendly urban planning. In this case, one works as a complement to the other. It will be possible for everyone to play a role in sustainable development if they adopt a cooperative attitude by avoiding competitive approach. Since urban planning depends on engineering, architecture, and everything social and political, it is in many ways an effort of technical profession, political will, and participatory of the people. Urban planning deals with both the development of open land (“greenfield sites”) and the revitalization of existing parts of the city. For example, while revising the DAP (Detailed Area Plan) of the capital Dhaka and its surrounding areas, all the information needed to consider the structure of soil layers inside each area, flood trend, protection of natural balance, etc. is not possible without the cooperation of civil engineers.

Role of Civil Engineers

The role of civil engineers in designing earthquake-tolerant buildings as part of sustainable development is undeniable. Civil engineers should coordinate with architects to assist them in designing earthquake-tolerant buildings. In this case, architects should also move forward by making possible changes in the design by emphasizing aesthetics as well as disaster resilience.

Column Size

The nature of the soil layers of Bangladesh, land development method, distance from the origin of the earthquake, all must apply the highest level of seismic detailing D category. This makes the minimum size of the column 16″. As an alternative, designing with shear walls can increase the minimum column size to 12″, although the cost increases slightly. However, shear walls should be arranged in the middle or around the building in such a way that symmetry is maintained, rather than in one corner. There are 2 courses for architects at qlearn.com.bd which explain these topics in detail. The two courses are Quality control of RCC building construction and Structural Engineering for Architects. Joint Shear Check Most civil engineers are seen completing structural designs without joint shear checks, which is a hindrance to the construction of earthquake tolerant buildings. In the past, most earthquakes around the world have seen building collapse through the failure of beam-column joints. Therefore, if the structural design is done without joint shear check, the building built at such a cost will remain risky.

Torsional irregularity check

If the position, arrangement of columns, beams and shear walls is not done properly, the building is likely to twist during the earthquake, which can be checked by the structural analysis program. It should be done with checks, positioning and arranging of columns and shear walls in such a way that the building does not twist. In addition to making the building earthquake tolerant, the cost of rods is also reduced. Torsional irregularity is not done by preserving symmetry with respect to both letters. Image: Torsional Irregular Building Plan Rod Matam Bending the rod at a 90-degree angle at the end is called matam. All the beam rods must be tilted 8-12″ where the beam-column joint ends at the end of the beam. For 16 mm dia rod, 8 inches, 10 inches for 20 millimeters, and 12 inches for 25 millimeters. It is not done properly on most sites, which is a major obstacle to the construction of earthquake tolerant buildings. It’s hard to do, but it’s a must. As an alternative, anchor couplers can be used, which makes construction easy and earthquake tolerant.

Liquefaction

If the silt and sand soil are below the water level, during the earthquake, the soil and water become soft like a liquid substance in vibration. This is called liquefaction. It does not have the carrying capacity of the soil during an earthquake. Can’t hold the pile from the side. Piles of 12-20 inches diameter are not suitable in these soils. If you determine the diameter of the pile by analyzing the liquefaction, if you design the foundation with a smaller number of piles of large diameter, the foundation will be earthquake tolerant and cost-effective. Otherwise, money will be wasted but the building will not be earthquake tolerant. For example, Bashundhara Baridhara Project and Jalshiri Housing Project have problems. Precast Driven Pile Problems and Solutions If the pile is already made and pressed or hammered into the ground after hardening, it is called a precast driven pile. Now a type of round pile called PHC pile is available to buy readymade inside which is hollow. The big advantage of the precast pile is that the quality of the pile can be ensured 100%. If the quality is poor, it breaks down while driving. In this case, broken piles can be canceled, and new piles can be made. The major disadvantages of the precast pile are highlighted below. – If you need a long pile, you have to give a joint. This problem can be solved with the right joint. – If there is a long pile, the diameter or size of the pile has to be increased, which is not possible. In this case, as a slender pile, this pile can fail during an earthquake. – If there is a possibility of liquefaction of the sand soil during an earthquake, the precast pile fails like a slender column. So, in this case, large size situ piles should be done. Precast pile can be inserted at any depth with diesel hammer. However, if there are structures or buildings in or around the city area, the vibration or vibration created by the diesel hammer can cause those structures to collapse or crack. For this reason, diesel hammers cannot be used. Hydraulic push pile driving machine can be used to drive piles without any vibration, but it is not possible to take the depth as much as possible. However, the required load capacity is obtained by inserting piles at low depths. Although there seems to be no problem with this, due to the liquefaction of sand soil during the earthquake, the load capacity decreases, and the building can collapse. The pile cannot be inserted to a greater depth with a manual hammer, but there is a possibility of damage to the surrounding structures due to vibration. So, using a manual hammer is not possible in most cases. Pile base grouting (pilebasegrouting.com.bd) can be used to remove the limitations of the precast pile. Before making the precast pile, the pipe should be kept inside the pile. By grouting the pile base after driving the pile, the soil under the pile can be made harder, which will not be liquefaction during the earthquake.

Situ pile problems and solutions

Situ piles are made by making deep holes inside the ground with machines and inserting rod cages inside it and then casting concrete. This pile can be made of any diameter or size and depth. The biggest disadvantage of situ piles is that it is extremely difficult to make good quality piles with domestic wince machines and tripods. In the absence of good technicians and labor, the quality control of situ piles is not easy. Due to the accumulation of soft mud and sand under the pile before the concrete casting of the pile, the bearing capacity of the soil under the pile is very low. Bentonite slurry is a mixture of sticky mud and water. If you do not use bentonite slurry during situ, the shape of the pile hole or boring is not right, the soil of the side is broken. Many people do not use this slurry to reduce costs. The quality of the situ pile is bad. Good quality situ piles can be done with rotary drilling rig. Rotary drilling rigs are expensive. If there are small diameter piles and a small number of piles, instead of rotary drilling rig, Bangla method is cost-effective, but it is difficult to pile quality situ in Bangla method. The internal load capacity of the situ pile is much higher than the load capacity of the soil which cannot be utilized. These problems can be solved cost-effectively by doing pile base grouting (pilebasegrouting.com.bd). Due to the grouting of the pile base, the bearing capacity of the soil under the pile increases, the number of piles decreases, the cost is reduced, and the foundation is earthquake tolerant. Use of Rebar Coupler To build an earthquake-tolerant building or structure, the beam-column joint has to be arranged with rods and all the rods have to be done properly. Another important thing is that through lapping or welding, the rod has to be paired in certain places of the beam and column. It is forbidden to put this pair or lapping beam-column inside or near the joint. But, in reality, it is seen that masons put a pair of rods inside or near the beam-column joint to reduce rod wastage. This puts the building at risk of collapsing during an earthquake. Using a rebar coupler increases the freedom of the rod jointing space. In addition to making the building earthquake resilient, the cost of rods is also reduced by preventing wastage. During earthquakes, the concrete outside the rod often cracks or collapses. It cannot take the load of the rod assembled through lapping. The rod assembled through the rebar coupler can take the load in this case. Therefore, rebar coupler is a must in earthquake resistant building construction.

Figure: Avoiding lapping of rod through rebar coupler.

Conclusion Planners, architects and civil engineers can contribute significantly to the sustainable development of Bangladesh through knowledge sharing, exchange of views, cooperation, coordination and respect.