 Asnur working as an assistant professor in civil department from Walton Institute of Technology, SolarPool. Today's class, we are going to discuss on arches and its types. These are the learning outcomes. At the end of this session, students will be able to identify the different types of the arches and their suitability. This is a arch, so there are technical terms. The intruders is the inner curve of the arch, whereas the extruders is the outer curve of the arch. This is the topmost portion which is called as the crown, that is the highest part of the extruders. The key, it is called as the portion below the crown, the rise, the vertical height of the crown, arch is called as the rise. So these are the abutements which are provided at the end of the arch, the supports given to the arch and the peers are also provided, which is intermediate support, which is provided in the series of the arches and the arched is known as the series of the arches in continuation. This is the haunch, which is the half portion from the springing line, this is called as the haunch, the springer, that is the wedge shaped unit which may be of a, which may be of a brick or the stone which is placed above the springing line is called as the springer. So an arch is generally a structural member, which is used in the building to build across the openings of the doors, windows or the cupboards, to withstand the load coming over the opening. So the support to the superimposed loads can be given by providing an arch or a lintel. So the arch supports the loads by the arch action, whereas the lintel supports the load by provide, it acts as the beam which transfers the load vertically to the supporting walls. So the arch is, it is a mechanical arrangement of the bricks or the stones, that is the wedge shaped units. These are placed around a curved line which mutually support each other. This is the classification of the arches which is based on the shape, shape of the arch. Second is the number of the centres of the arch and third we have the workmanship and the material used. So out of this we will be discussing on the shape. These are the arches based on the shape. So first we have the flat arch, second is the segmental arch, third is the semicircular arch, fourth is the horseshoe arch, next is the pointed arch, venitian arch, florentine arch and the reliving arch. This is the flat arch. So from the sketch itself we can know that this is the extruders, the outer part of the curve and this is the intruders. It is perfectly flat and horizontal. So a skew back is provided which is at an angle of 60 degrees. So it is an angle of 60 degrees. So the depth of the arch it is around 3 to 4 courses. A course is nothing but where the bricks are placed in a single course it is called as the course. So the depth will be around 3 to 4 courses and the angle is 60 degrees. So this is used for the light loads. It is not strong enough so for that the span is limited. It is around 1.5 meters and if at all you want to use it for the more span the steel reinforcement has to be provided. Next we have the segmental arch. Here you can see in the sketch that the extruders it is a the shape of the arch itself is a segmental shape and here you can see that the centre of the arch is below the springing line. This is the springing line which joins the springing points at the either ends. So this is the springing line. Here you can see that this is the voices. Voices is the wedge shaped units which may be of brick and the stone and the skew backs are provided. The pier it is a intermediate support given to the arch. So in this type of the arch the depth of the arch is around 20 centimeter 30 centimeter and so on. It is used for the various types of the openings which may be of different sizes. It is used in the buildings the semicircular arch. The from the name itself you can say that the shape of the arch is semicircular shape but here you can see that the centre of the arch lies on the springing line itself so that the centre of the arch so that we get a semicircular shape. Next we have the horseshoe arch. So the horseshoe arch it is the shape of the arch is horseshoe and it has a more deeper curve of a semicircular shape and it is used for the architectural purpose due to the shape of the arch. So this is the crown placed and this is the key. These are the abutments above the before the these are the springing line. It is a line imaginary line joining the curve of the arch. These are the springing above that we have the springer where we place the where we place the wedge shaped unit which may be stone or the brick. Next we have the pointed arch. In the sketch itself you can see that this is a pointed arch that means the two arcs two arcs are joined to each other where at the intersection you get a pointed shape that is called as the pointed arch so it is a two centred arch and due to the shape of due to the shape of this arch it is called as the gothic arch also and it is used for the architectural purpose. Next we have the venitian arch. So this is one form of the pointed arch also here you can see that the crown it is the depth of the crown is more it is more and also it is used for the architectural purpose due to its due to its look and here the here the arch is drawn using the four centre's arch that is the the inner the inner circle it can be drawn by using the two centres whereas the outer arch can be drawn by using two centres. So total you will be needing four centres for drawing this arch. Next we have the forentine arch. This particular arch you can see that it is similar to the venitian arch except that the inner curve of the arch is a perfect semicircle. So this semicircle is drawn by using a single centre. To draw this semicircle we need a single centre point and the outer line it is a curve. So total for this arch three centres are needed. This is used for the architectural purposes. Next we have the reliving arch. So this type of the arch is constructed here you can see that this is the flat arch and below that you have a wooden lentil also. So the reliving arch itself can be provided above the flat arch or the wooden lentil to support the load coming over that arch. So this wooden lentil it can be even replaced also without disturbing the stability of the structure and even the this type of arch is provided to withstand the load coming over this arch. So here you can select the correct answer for the below question. So identify the type of the arch given below. So here is a sketch given to this as here is an angle given as the skew back. You can see that the extruders and the intruders they are perfectly horizontal but a skew back angle is given as 60 degrees and the centre you can see that the centre is much below. So here are the options as which type of arch it is from the sketch itself you have to identify with. First we have the flat arch, second the venitian arch, the horse shoe arch and the reliving arch. So think for a while and answer it. So flat arch is the correct answer for that when we have this in the centre below and it is perfectly flat in shape. The one which we had discussed before the this sketch is similar to that. These are the references which I have. Thank you.