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ABSTRACT: Recently the development of coastal zone has been advancing, and the chance of human activity has increased near the sea." The human body and buildings are harmfully influence by the ultraviolet ray. Especially, reflection on the sand and sea surface by the sunlight is given as a factor which is different from the land. This report shows the relation among ultraviolet reflectance, sand components, kinds of sand and sand's lightness. Consequently, these things were cleared. The ultraviolet reflectance on sand can be classified by sand's lightness. As sand's lightness becomes higher, the ultraviolet reflectance increases. 1. PREFACE In recent years, activities around coastal area have extended to ocean development and various life styles of humanity. Here we must take account for peculiar environmental condition of the ocean. When lighted environment, the effect of ultraviolet radiation in coastal zone is higher than that in terrestrial zone due to the reflection on the sea surface and sand or due to atmosphere of ultraviolet radiation transmittance. On buildings discoloration and decay of coating are accelerated. In order to have a safe and comfortable ocean environment, it is needed to clarify the condition of ultraviolet radiation and its reflection on the coast. 2. Purpose It is considered that the ultraviolet reflectance differs in kinds of sand. This research aims to propose an index for the future development of artificial beach through the measurement of ultraviolet reflection intensity. Therefore it is needed to clarify the ultraviolet reflectance of sands in several beaches. This report shows measurements of ultraviolet reflectance of sands in order to investigate the relation among reflectance, sand components and kinds of sand. And the relation between the reflectance and sand's lightness was clarified. Figure 1 shows the ultraviolet reflection model on beach.
ABSTRACT: Tension Leg Platform (TLP) is recognized to be an aseismatic structure and earthquake has never been considered as an external force in its design. However, the vertical component of seismic force is an important item to take into consideration, because it is directly superposed to pretension of tendons1,2). The purpose of this report is to set up an analytical model for determining response of a TLP under unbalanced initial tension when the TLP is subject to vertical seismic excitation. INTRODUCTION Hull of a TLP is moored to the seabed by four tendons. Tendon tension acts equally to the four tendons. As TLP receives various environment forces such as wind force, wave force and current force, it moves to the horizontal direction. The horizontal displacement is called "offset". When hull is under offset condition, the tendon tensions become unbalance. Earthquake response of TLP under unbalanced tensions is different from that of balanced tensions. Researches on snap load and tendon failure of TLP are already reported3,4). However, they do not have dealt with response of TLP under unbalanced initial tensions. In this research, we have constructed a 3-dimensional analytical model which is able to simulate the unbalance state of a prototype of the TLP. By using it, we have carried out numerical calculation in order to st.udy basic response of the TLP due to seismic excitation under unbalanced initial tensions. CALCULATION AND RESULTS Analytical model and condition A prototype TLP is shown in Fig.4. The particulars of the TLP are shown in Table 16). The earthquake introduced at bottom of tendons is vertical motion of EI-Centro wave. The initial length of tendons is 469.5 m. Due to initial tension(=29.4 MN), tendon length becomes 470.0 m. Unbalanced state of initial tension occurs due to the change of the tendon length.