Analysis of Use of Welded Angle and Drop Hollow as Reusable Temporary Supporting in Metal deck Slabs Viewed from Performance of Costs and Time

Like the project in general, slab work on Project Indonesia 1 uses one material, namely metal deck. The upper structure slab consists of 64 floors with a majority of 90% using a metal deck system. Where these components require support that can carry the workload, rebar, and fresh concrete. Starting with Metaldeck's non-reusable / fixed supporting (angle & anchor) design which is quite difficult to apply in the field, it has an impact on increasing time and increasing the cost of work. So the engineering team has the innovation of replacing non-reusable / fixed supporting material (angle & anchor) with reusable material (angle & drop hollow). Cost analysis is sought by calculating the RAB (Cost Budget Plan) using the unit price analysis used by the DKI Jakarta Government and how efficient the time gained. Based on the results of calculations and interviews with relevant experts on the project, the implementation of temporary supporting work costs was carried out using a non-reusable method of Rp.3,211,000,000.00. As for the implementation of the reusable method of Rp.649,916,800. There is a difference in cost between the non-reusable and reusable methods of Rp. 2,561,083,200.00. Where to implement the temporary supporting reusable method is cheaper than using the non-reusable initial method. Then in terms of installation time, the temporary supporting using the non-reusable method was 520 days while for the reusable method it was 260 days. There is a difference between the non-reusable and 260-day reusable methods. The results obtained that the use of Welded Angle & Drop Hollow as Temporary Supporting is more effective and efficient than using the initial Non-reusable


BACKGROUND
From year to year building construction in Indonesia is growing, especially in the world of construction. The increasing number of construction service providers lately should be offset by cost savings, quality in accordance with the standards and also the efficiency of the project work time. In Indonesia currently competing in the construction of high-rise buildings. And one of them is the Indonesia 1 Jakarta building. Acting as the main contractor of PT Acset Indnusa, tbk conducted a Joint Operation with CCEED (China State Construction Engrg. Corp. Ltd).
The construction of the Indonesia 1 Jakarta building is one of the high-rise building projects that will become one of the tallest buildings in Indonesia. This building has two towers. Covering 58 floors, lower roof, roof top with helipad, (Tower North) & 59 floors, lower roof, roof top (Tower South), 7 basements and will also have bridges connecting the two towers. Because the main material used in the construction of Indonesia building 1 uses composite materials, it must really take into account the earthquake forces that occur. Regulated in the calculation of reinforced concrete structures which are in SNI 1726, ASTM A615, and ACI 318-14.
Like most projects in the slab Project Indonesia 1 uses one material, namely metaldeck. The upper structure slab consists of 58 floors with a majority of 90% using a metaldeck system. Where these components require a support that is able to carry the workload, rebar and fresh concrete. Starting from the Metaldeck non-reusable / fixed supporting design (angle & anchor) which is quite difficult to apply in the field, it gives an impact on increasing time and increasing the cost of work. So the engineering team has the VOLUME 2 │ NUMBER 3 │ MAY 2020 Available online at http://proceedings.worldconference.id. ISSN: 2656ISSN: -1174

IDENTIFICATION OF PROBLEMS
Based on the background that the author has described, identification of problems based on observations in the field, namely: The time needed for the installation of temporary support exceeds the specified schedule. The process of implementing non-reusable / fixed suppoting metaldeck (angle & anchor) is difficult to apply so reusable temporary support is needed to shorten the processing time. The need for saving post in Temporary Supporting work.

FORMULATION OF THE PROBLEM
Based on the identification of the problem and so that the discussion is more directed according to its purpose, the problem is formulated as follows: a) Can reusable temporary support improve time performance on Project Indonesia 1? b) What are the benefits and costs if reusable temporary support is applied to Project Indonesia 1?

PURPOSE AND OBJECTIVES
The aims and objectives of this research are: a. Knowing that using reusable temporary support can improve the time and cost performance of Project Indonesia 1. b. Knowing how much profit is generated by the reusable temporary support method through detailed calculations.

Methodology
The preparation of the research water diagram is: 1) The author begins the research. At this stage the authors conducted research in the Indonesia 1 Jakarta building construction project. 2) The activity of identifying problems (evaluation) is carried out after a literature study and problem analysis. By identifying the problem, it is expected that the final task examiner will clarify what problems will be addressed in this final task, as well as the boundaries of the problem so that it can assess the problem efficiently. 3) In the process of carrying out this final task requires theoretical foundations that support the problem to be tested. Through library research in the form of scientific journals, papers, books and articles related to research topics. It is hoped that it can add to knowledge and learn basic theories that will be used as a reference. 4) Furthermore, the authors conducted primary data collection and secondary data needed to make this final project include: Field observations and interviews Related Photos Daily record sheet Project data Books and journals 5) Data analysis is the process of calculating and planning comparative costs and duration of work using non-reusable fixed supporting material (100x100mm steel) with welded angle & drop hollow material (50x50mm): Method of Implementation Analysis of the method here is in the form of a calculation of the installation method of metaldeck along with a temporary suppoting reference to the analysis of the implementation of the full system VOLUME 2 │ NUMBER 3 │ MAY 2020 Available online at http://proceedings.worldconference.id. ISSN: 2656ISSN: -1174 Implementation cost In this stage, it will take into account the volume of each temporary support installation work of each non-reusable and re-usable material, then analyze the unit price of goods, work wages, and costs Execution time In the re-usable time of temporary supporting using welded angle & drop hollow will be calculated what work is needed and analysis of the completion time in the project area so that the length of work planned.
The analytical method I reviewed from the time of implementation of each temporary supporting system was obtained from direct observation in the field. 6) After analyzing the data obtained, conclusions can be drawn from the results of the analysis. This stage provides synchronization between the purpose of writing and the boundary of the problem with the analysis conducted, which is expected to be used as input for the readers. 7) Provide information about the study of the cost and time of the implementation of temporary supporting before using the reusable system and after reusable use in the Indonesian building project 1. Research is completed

GENERAL REVIEW
This chapter will discuss the process of analyzing the time difference and the cost of installing temporary supports using the non-reusable method (angle & anchor) with the re-usable method (welded angle & drop hollow). So that later it will be known which temporary supporting installation method is more efficient in terms of cost and time.
In this project the initial design is in accordance with the Indonesian building construction contract 1 using the initial method which is non-reusable. Where temporary supporting for metaldeck uses angle & anchor while the initial material used is hollow 100mm x 100mm besides the cost is quite expensive and heavy when carried out in the field. In the installation of temporary supporting non-reusable methods, it requires more than 2 people so that time efficiency is reduced.
From the field implementation, the contractor has re-evaluated, so that the installation of temporary support can be more effective and efficient. The contractor made an innovation where the non-reusable method (anchor & angle) would be replaced using the reusable method (hollow 50x50mm & angle) where. The re-usable method replaced the hollow material that had been 100x100mm with a hollow size of 50x50mm. The re-usable system itself aims to make the installed hollow material reusable for the next floor. This reusable method is easier to apply in the field and saves enough money. In this chapter, we will explain further about the cost and time analysis of the two temporary supporting installation methods.  In Table 3.2 it can be explained that not all flooring uses metaldeck, on floors 3,4,5,20,20 mezzanine, 21 uses conventional conventional slabs. The use of conventional slabs is caused by bridges and joint connections on the related floor. While on the 59-62 (north tower) and 59-64 (south tower) floors are used as roofs. So from Table 4.5 the temporary supporting installation work using non-reusable methods is 520 days.

Analysis of the Reusable Method of Ordering Time
Analysis of the productivity of each job is needed to determine the duration of time needed for each job. Productivity is the ability of tools and workers can complete a job within the work unit's time. Productivity data obtained from interviews with discussion, and data collection. The duration of implementation time is obtained by calculating the duration of installation time on each work item. VOLUME 2 │ NUMBER 3 │ MAY 2020 Available online at http://proceedings.worldconference.id.
ISSN: 2656-1174 (online) it can be explained that not all flooring uses metaldeck, on floors 3,4,5,20,20 mezzanine, 21 uses conventional conventional slabs. The use of conventional slabs is caused by bridges and joint connections on the related floor. While on the 59-62 (north tower) and 59-64 (south tower) floors are used as roofs. from Table  4.7 the temporary supporting installation work using the reusable method is 260 days.

Unit Price Analysis for Material and Non-Reusable Method Work
The unit price analysis used as a reference is the standardization of unit price of materials, DKI Jakarta's wages contained in the attachment sheet. After observing the field test the types of material used in the installation work are 100x100x8mm elbows and M12-300 mechanical anchors. To analyze the cost of installing temporary supports using a non-reusable method, see the following From field observations to install non-reusable temporary support this method still uses a 100x100mm hollow and the elbows to be anchored. In the installation there are 2 work items. The first item is mounting elbows.
For the elbow installation work, it must be noted that in one work floor there are 40 span metaldecks, with each 2.2d span metaldeck. In each floor there are 4 elbowmakers and 8 people for each elbow. The second item is the installation of mechanical anchor with type (Anchor M12-300) there are 7 ankle points that must be installed on each floor. The installation requires 5 anchor workers. So that the total material costs and total wages will be calculated as the following table: 22nd-58th Floor 36 floor VOLUME 2 │ NUMBER 3 │ MAY 2020 Available online at http://proceedings.worldconference.id.

Total Lantai 52 floor
In Indonesia 1 project there are 2 towers namely South & North tower. From the above floor data we can calculate the total material price and total wage price as follows:   From the table above calculation, the total material price is Rp. 3,078,400,000.00 and the total price of the workers is Rp.132,600,000.00 so that in the process of installing temporary support using the initial method (non-reusable) a total budget of Rp.3,211,000,000.00 is obtained. VOLUME 2 │ NUMBER 3 │ MAY 2020 Available online at http://proceedings.worldconference.id. ISSN: 2656ISSN: -1174

Unit Material Analysis and Reusable Method Work
For the analysis of the cost of installing temporary supports using the reusable method. There are 3 jobs in installing this temporary support. From the writer's observation in the field. The first work of mounting the elbow size of 100x100x8mm volume that can be cured is shown in the following table:

DISCUSSION OF WORK TIME RESULTS
From the results of the analysis of the work time above shows clearly that the temporary supporting installation work using the reusable method (angle & drop hollow) is more efficient and effective than the nonreusable system (anchor & hollow). This is because the work of temporary supporting installation using nonreusable methods (anchor & hollow) requires some quite expensive materials and also installation that is quite difficult if done only with 1 worker. So the time used in the installation process is inefficient compared to the VOLUME 2 │ NUMBER 3 │ MAY 2020 Available online at http://proceedings.worldconference.id. ISSN: 2656ISSN: -1174 reusable method. The reusable method itself only requires 1 worker for the 50x50mm hollow installation process so that work can be completed faster. The time difference of the temporary supporting installation work uses the non-reusable method with the reusable as follows: Tabel 3.14 The time difference between installing temporary supporting methods is non-reusable and reusable

DISCUSSION OF WORK COST RESULTS
From the calculation results, obtained the cost of temporary support installation work using a nonreusable method of Rp.3,211,000,000.00. As for the cost of implementing temporary support installation using the reusable method Rp.649,916,800.00. There is a difference in the cost between the temporary supporting installation work with the non-reusable and reusable methods of Rp. 2,561,083,200. Where for the cost of implementing a temporary supporting installation with a reusable method is cheaper than the non-reusable method. Comparison of the prices of the two temporary supporting systems in the installation of the metaldeck slab is due to the high price of material and wages of workers. So that the reusable system is very effective in the Indonesian project 1.