FIELD OF INVENTION
The present invention relates to a structural arrangement for 2 legged trestle more than 25m for double conveyor gallery in coal handling plant adopted in thermal power plant. More particularly the present invention is about the design, optimization and standardization of the complete 2 legged trestle more than 25m for double conveyor gallery structure that will provide new and stable design than the existing structure.
BACKGROUND OF THE INVENTION
The 2 legged trestle more than 25m for double conveyor gallery structure is one of the components in coal handling plant. The 2 legged trestle more than 25m for double conveyor gallery helps in supporting the galleries which is used in transporting the material from the port to bunker or storage yard and then to the boiler. These trestles can be of various heights and width depending on the technical requirement.
The existing 2 legged trestle more than 25m for double conveyor has 2 frames and which per se consist of 4 columns made up of built up section. It consists of horizontal beams and front bracings for connections. Since it has built up flat members it will have more welding length and hence more fabrication and erection time. Because of the built-up section the wind load acting on the structure will be more due to more exposed surface area which can be avoided in pipe sections. There is no practice of optimization of the structure and hence it will be mostly over designed.
The present invention is regarding the complete design optimization of one such standard 2 legged trestle more than 25m for double conveyor gallery structure. It contains two frame structure held by lacings and consists of 4 columns and each column is made up of four individual legs which acts like built-up column. Each segment is divided by horizontal beams and vertical bracings.

OBJECTS OF THE INVENTION
Therefore it is an object of the invention to propose a structural arrangement for 2 legged trestle more than 25m for double conveyor gallery in coal handling plant which enables reduction of total weight of the structure due to optimization of structural components.
Another object of the invention is to propose a structural arrangement for 2 legged trestle more than 25m for double conveyor gallery in coal handling plant which is capable of reducing welding requirements of built up section by using standard pipe sections.
A further object of the invention is to propose a structural arrangement for 2 legged trestle more than 25m for double conveyor gallery in coal handling plant which can withstand heavy wind load condition.
A still another object of the invention is to propose a structural arrangement for 2 legged trestle more than 25m for double conveyor gallery in coal handling plant which is able to operate at high heights from ground.
A still further object of the invention is to propose a structural arrangement for 2 legged trestle more than 25m for double conveyor gallery in coal handling plant which enables to prevent excessive deflection of the structure and to limit the stresses up to acceptable safe limits under severe wind load conditions.
SUMMARY OF THE INVENTION
Accordingly the proposed 2 legged trestle for a double conveyor gallery structure to the particular coal handling plant adopted in thermal power plant comprises of two frames with two columns each and each column comprises of four legs. It is divided horizontally at appropriate intervals and connected by horizontal lacings. It is also connects through vertical lacings and vertical bracings for additional strength. Depending on the height of the structure the number of segments changes.
These frames per se constitute plurality of legs connected horizontally and vertically through lacing to form a single column of the structure. Two similar column constitute one frame and two similar frames makes a 2 legged trestle.

The present invention will give a new structural arrangement for the 2 legged trestle for double conveyor gallery structure. The system has advantages of improved load stability. This structure is fit to be used in high wind zone. Due to the design simplification it will be easy to fabricate and erect these structures in site. From the erection point of view it will reduce amount of inventory.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
Fig. 1 - Shows an isometric view of the 2 legged trestle for double conveyor gallery structure according to the invention.
Fig. 2 - Shows the expanded view of first segment (A) as mentioned in fig. 1 according to the invention.
Fig. 3 - Shows the side view of the 2 legged trestle for double conveyor gallery structure according to the invention.
Fig. 4 - Shows the front view of 2 legged trestle for double conveyor gallery structure according to the invention.
DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT OF THE INVENTION
Figure 1 shows the overall isometric view of the 2 legged trestle for double conveyor gallery structure in accordance with a preferred embodiment of the invention. In figure 1, the box A, shows the first segment of the 2 legged trestle. The segments are divided at particular interval and each segment is divided into four sub-segments at equal intervals for lacing connection. The 2 legged trestle for double conveyor gallery consist of two frames (P, R and Q, S) which are placed at certain interval side by side to form a built-up laced column structure.
The novel structural arrangement of 2 legged trestle of more than 25m for double conveyor gallery structure consist of two set of frames placed at appropriate intervals in both X and Z directions in order to form a laced column which will act as single unit.

A single frame will consist of two columns which per se consist of two legs connected horizontally with horizontal lacing and vertically with vertical lacings. The two columns are connected by horizontal beam at a particular interval as segments and each segment is divided equally by horizontal lacings. The two columns are also connected by inclined bracings.
The following are the parameters considered for the modeling the structure. It depends on the technical requirements.
1) Top width - Width of the double conveyor gallery which will be placed at the top.
2) Bottom width - Width at the bottom of the trestle.
3) Height of the structure
4) Height of the first segment
5) Trestle breadth - Width between two frames.
6) Front spacing - Width between two legs.
According to the invention, the legs in figure 2, (1, 2, 3, 4, 5, 6, 7, and 8) are made up of pipe section placed at equal distance considering the top width, bottom width, trestle breadth and front bracing dimensions. It is laced together horizontally in front by horizontal beam (10) and at the side with side horizontal lacing (13). It is connected as well as vertically at front (9, 12) and side (14, 15). It is also connected by inclined bracing (16, 17) at front and back. The total trestle is divided into different segments and each is sub divided into four by horizontal lacing (11). The number of segments depends on the height of the structure. The arrangement works for heights from 25m-70m from ground.
The A type bracing used in the front has the advantage of lesser solidity ratio due to reduction in length of bracing compared to X type bracing. The cumulative effect will be seen in the reduction of wind load along the conveyor direction.
All the members are made up of standard pipe sections, in order to avoid the built-up sections, which has the following advantages

1) The load carrying capacity increases because of increase in moment of inertia.
2) Circular section may have as much as 30 to 40% less surface area than that of an equivalent rolled shape and thus reduces the cost of maintenance, cost of painting.
3) There is no better section than the tubular one for torsional resistance.
4) Tubes are of special interest to architect from an aesthetics viewpoint.
5) The external surface of the tube does not permit the collection of moisture and dust thus reducing the possibility of corrosion.
6) Under dynamic loading the tube has a higher frequency of vibration than any other cross section including a solid round bar.
The major loads that will act on this structure will be self weight, dead load if any i.e., cables etc., live load, wind loads and loads from the conveyor. The pipe section will help in reduction of total wind load acting on the structure. The following table is a reference from IS 875 Part III code Table 28 for Force co-efficient for single frame.
Force coefficient is a value used in the calculation of wind load. Since force coefficient (Cf) for pipe is less than that for flat member, total wind load acting on the structure for the same dimension, the pipe section structure will have less wind load acting than the flat member structure. For example, for an average solidity ratio of 0.3 and given topographical condition, the percentage reduction in wind load acting on the structure is
approximately 29%

While the illustrative embodiments of the disclosure has been described above, it will be recognized and understood that various modifications can be made to the embodiments and the appended claims are intended to cover all such modifications which may fall within the spirit and the scope of the disclosure.

WE CLAIM
1. A structural arrangement of 2 legged trestle of more than 25m for double conveyor gallery structure comprising;
arranging two set of frames (P, R and Q, S) structure comprising four columns; placing the said frames at predetermined interval in both X and Z directions to form a laced column acting as single unit;
arranging each column made up of four individual legs acting as built-up column; wherein the legs (1, 2, 3, 4, 5, 6, 7 and 8) are laced together horizontally in front by horizontal beam (10) and at the side with horizontal lacing (13) and vertically at front (9, 12) and at side (14, 15) by vertical lacings when the two columns are connected by horizontal beam at a pre determined interval as segments wherein each segments is divided equally by horizontal lacings (11) where the two columns are also connected by inclined bracings (16, 17) to result a cumulative effect in the reduction of wind load along the conveyor direction.
2. A structural arrangement as claimed in claim 1, wherein all the members of the said arrangement are made up of standard pipe sections.
3. A structural arrangement as claimed in claim 1, wherein the arrangement works for heights from 25m-70m from ground.

ABSTRACT

A structural arrangement for 2 legged trestle of more than 25m for double conveyor gallery structure with two set of frames (P, R and Q, S) are placed at appropriate intervals at both X and Z direction in order to form a laced column which acts as a single unit. Two frames consist of four columns. Each column has four legs. The legs (1, 2, 3, 4, 5, 6, 7 and 8) are laced together horizontally in front by horizontal beam (10) and at the side with horizontal lacings (13) and vertically at front (9, 12) and at side (14, 15) by vertical lacings and the two columns are connected by inclined bracings (16, 17) to result a cumulative effect in the reduction of wind load along the conveyor direction.