Available online at www.CivileJournal.org Civil Engineering Journal (E-ISSN: 2476-3055; ISSN: 2676-6957) Vol. 10, No. 06, June, 2024 1863 The Effectiveness of Inclined Pile Breakwater on the Transmission Coefficient Lukman Nurzaman 1* , Pitojo Tri Juwono 2* , Very Dermawan 2 , Indradi Wijatmiko 1 1 Department of Civil Engineering, Faculty of Engineering, University of Brawijaya, Malang, Indonesia. 2 Department of Water Resources Engineering, Faculty of Engineering, University of Brawijaya, Malang, Indonesia. Received 06 February 2024; Revised 09 May 2024; Accepted 17 May 2024; Published 01 June 2024 Abstract A breakwater is a structure designed to protect coastal areas by breaking and reducing the force of incoming waves. Waves that propagate through a wave dampening building will have some of their energy reflected (reflection), some of their energy transmitted (transmission), and some of their energy destroyed (dissipation). The effectiveness of wave-breaking structures in protecting coastal and harbor waters can be seen from how much wave energy the building can reduce. In this research, the performance of the wave breaker will be seen from the values of wave transmission (Kt) and wave reflection (Kr) with an inclined pile building structure. Reflection and transmission analysis of the results of 2D physical model testing of wave breakers with inclined pile structures are needed to optimize their use. Laboratory test results prove that this Inclined Pile Structure breakwater is quite effective in scenarios that have smaller Kt values and larger Kr values. In this experiment, testing was carried out with several parameters, namely the slope of the pile, the distance between the piles in one row (or distance between pillars), the distance between the tops of the piles (or distance between rows of piles), and the depth of the water. The Kt value in the model α=45°; D=1.69 cm; b=5 cm is 0.603 compared to the model α=60°; D=1.69cm; b=5 cm, Kt value is 0.652. This shows that the inclined pile structure of breakwater is more effective with a pile slope of 45° than with a pile slope of 60°. Keywords: Inclined Pile Breakwater; Reflection; Transmission; Wave. 1. Introduction Coastal areas are an important part of and have a significant influence on a country's economy, including developing and revitalizing coastal tourism and building the environment and stability of the urban environment [1, 2]. Natural phenomena such as waves, winds, tides, and currents near the shore have an impact on the beaches and the stability of the coastal zone [3]. The basic purpose of breakwater is to protect a part of a shoreline, a structure, a harbor, or moored vessels from excessive incident wave energy when the waves hit the breakwater and they lose a lot of energy [4, 5]. Coastal protection has been developed with conventional breakwaters, which have high reliability and efficiency in wave dissipation. The requirement of a breakwater is to allow the least number of waves to be transmitted to its side of the coastal zone. However, the environmental sustainability of coastal structures depends on the need for raw materials and their significant impact on the surrounding environment, which results in permanent changes in the coastline to the surrounding environment [6]. * Corresponding author: lucky_pisces81@yahoo.com; pitojo_tj@ub.ac.id http://dx.doi.org/10.28991/CEJ-2024-010-06-09 © 2024 by the authors. Licensee C.E.J, Tehran, Iran. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC-BY) license (http://creativecommons.org/licenses/by/4.0/).