INTERNATIONAL JOURNAL OF CIVIL AND STRUCTURAL ENGINEERING Volume 1, No 4, 2011

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1 Evaluating the effect of penetration depth of a previous sheet pile quay wall on the seismic behavior of newly installed open type wharf Reza Dezvareh 1, Khosrow Bargi 2 1 Student of Master of Science, Department of Civil Engineering, College of Engineering, University of Tehran, 2 Professor, Department of Civil Engineering, College of Engineering, University of Tehran rdezvareh@alumni.ut.ac.ir ABSTRACT Regarding the great important role of marine transportation and existence of hundreds of kilometers of marine boundary in Iran, it must simultaneously develop world maritime transportation and ports, plus constructing new ports and berths, also present ports and berths to develop and enhance the present capacities is necessary. Construction of a new Open Type Wharf in front of available Sheet Pile pier is an offered method in this paper to development and retrofitting the Sheet Pile pier. This research based on numerical modeling is performed. Two Jetties by one of the finite element software such as ABAQUS will be modeled. This can significantly increase capacity of open type wharf and certainly, the new pier cost will be reduced severely. Keywords: Coastal Engineering; Sheet Pile Quay wall; Open Type Wharf; Finite Element Method. 1. Introduction Docks are among the most frequently constructed on shore marine structures with significant importance. The stochastic nature of the loads imposed on the docks (i.e. earthquake, vessel impact), beside the geotechnical sediment dredging concerns, make these structures different from the ordinary civil engineering issues. The common types of docks are Open Type Wharfs, caissons and Sheet Pile Quay walls. Increase of ship capacities demands for berthing structures with more strength and larger widths and draughts. Therefore, beside construction of new ports and docks, it is necessary to improve and progress the present docks. This research studies a different method of retrofitting for the docks, in such a way that the old Sheet Pile Quay wall that has lost its initial strength because of an earthquake or other reasons is stabilized and strengthened using an Open Type Wharf constructed in front of it. This paper will study the effect of the present dock on the lateral bearing capacity of the new Open Type Wharf and as well, it will verify the importance degree of reducing the construction expenses of the new Open Type Wharf regardless of the old dock. To due the diversity of the presented theory s aspects and as the author has found no such a matter in the technical literature, it has been decided to investigate Port of Nowshahr 1014

2 Sheet Pile Quay wall as a case study concerning the earthquake effect as the lateral load. 2. Case Descriptions and Modelling 2.1 Sheet Pile Quay wall Presented in the following table, are the properties of Port of Nowshahr Sheet Pile Quay wall with a Z section used as the case study. Figure 1: The properties of Port of Nowshahr Sheet Pile Quay wall Since the draught depth is about 6 meters, the Z section has been modelled as cantilever (with no lateral support). Regarding the soil properties presented in the following table, the sheet pile length was assumed 14 m with penetration depth of 8m. Table 1: Soil properties As explained in case description, the sheet piles have lost their initial strength. This matter needed the model stages to firstly count for penetration depth reduction, followed by the reduction of Z section thickness while the effects of the each on the new Open 1015

3 Type Wharf were studied and compared. The importance of site visit and field investigations for obtaining most logical results must be hereby mentioned. 2.2 Open Type Wharf (Pile Supported Wharf) The Open Type Wharf comprises three rows of steel piles with the diameters of 70 cm and the thickness of 12mm installed in 5 meter spans. Being driven in front of the Sheet Pile Quay wall, the height of each pile is 20 m, while the penetration depths are about 14m. The concrete deck of the pier is 70cm thick and it has been designed regardless of the present Sheet Pile Quay wall. 2.3 Connection of the Two Docks The two docks of this research have been given complete restrains and hinge, whereas the effects of all have been compared. 2.4 The Used Software The finite element package used in this research is ABAQUS and it has been chosen due to its soil and structure modelling, soil structure interaction and dynamic analysis capabilities. (Dynamic load: Earthquake Record of Oakland 0.2g) 3. Result Analyses and Discussion As previously mentioned, the effect of the following parameters on the pier and deck tip deflection have been studied and presented here: 1. Penetration Depth of Sheet Pile 2. Connection between Sheet Pile Quay wall and the front Open Type Wharf The discussions will end in a comparison between the mode in which the Sheet Pile Quay wall is present and when there is no connection between Open Type Wharf and Sheet Pile Quay wall. 3.1 Penetration Depth of Sheet Pile As the design penetration depth of sheet pile is 8m but it is assumed to been reduced to 6m during the time or by earthquake, a comparison between the design and real penetration depths are presented here. The deflection of the Open Type Wharf tip for two different penetration depths were studied using the numeral model in hinge and fully constrained modes during dynamic analysis. 1016

4 Figure 2: Open Type Wharf tip deflection for hinge connection Figure 3: Open Type Wharf tip deflection for constrained connection As can be seen in here, the Open Type Wharf tip deflection shows a dramatic increase with the reduction of sheet pile penetration depth. Especially, this increase in the constrained mode is 2 to 3 times that of hinge connection. 3.2 Connection between Sheet Pile Quay wall and the front Open Type Wharf Due to the lack technical literature on this type of connection between the two decks, the results of study and comparison between fully constrained and hinge connections between the present Sheet Pile Quay wall and Open Type Wharf deck are hereby presented. The deflection of the Open Type Wharf tip for two different z section thicknesses and penetration depths were studied using the numeral model during dynamic analysis. 1017

5 Figure 4: Open Type Wharf tip deflection for penetration depth of 8m Figure 5: Open Type Wharf tip deflection for penetration depth of 6m It can be noticed that tip deflection for hing connection is more that that of constrained ones. The connection type effect is also seen to undergo reduction with the reduction of sheet pile penetration depth. It can be illustrated through the fact that the tip deflection corresponding to the penetration depth of 6m in both hinged and constrained modes are much less than those corresponding to the penetration depth of 8m. 3.3 The Effect of present Sheet Pile Quay wall on the new Open Type Wharf This section discusses the effect of the present Sheet Pile Quaywall on the new Open Type Wharf. For this purpose, the Wharf is analyzed both in connection with the Sheet Pile and without of it. 1018

6 The results of the numerical model for the deflection of Open Type Wharf corresponding to two different penetration depths during dynamic analysis is presented in the following curve which shows the Wharf tip deflection in the absence of Sheet Pile Quaywall. Figure 6: Open Type Wharf tip deflection with and without the Sheet Pile Quay wall It can be seen that the connection of the present Wharf to the Sheet Pile Quay wall can dramatically reduce the deflections of the Wharf tip. With the reduction of the penetration depth, the deflections will approach those of Open Type Wharf in the absence of the Sheet Pile. Nevertheless, the minimum difference of 10 to 12 centimetres between the two still exists. 4. Summary and Suggestions This paper aims to study the seismic behaviour of an Open Type Wharf connected to an old Sheet Pile Quay wall through a logic procedure. For that, the two Quays and their connection have been modelled and exposed to a realistic earthquake record. Afterwards, and due to the importance of Quay tip deflection on its behaviour, this important parameter was studied in different modes and the results were presented in the previous sections. In the end and in order to prove the importance of this method in the reduction of Open Type Wharf dimensions (section) and increase of its lateral bearing capacity when connected to the old Sheet Pile Quay wall. The results of this research can be divided into two main categories: 1. parametric studies results 2. design applicable results 1019

7 4.1 Parametric Studies Results The parameters studied in this study include the Sheet Pile thickness and type of connection between Sheet Pile Quay wall and the Open Type Wharf. 1. Sheet Pile Penetration Depth: The Open Type Wharf tip deflection shows a dramatic increase with the reduction of sheet pile penetration depth. Especially, this increase in the constrained mode is 2 to 3 times that of hinge connection. 2. Connection Type: The Quay tip deflection corresponding to hinge connection is more than that of constrained connection. It s also seen that the reduction in penetration depth reduces the connection type effect. 4.2 Design Applicable Results The results of this research suggest that: 1. In order to reach an optimal design for a Open Type Wharf, the use of an old Sheet Pile Quay Wall in the and connecting the new Open Type Wharf to the front of it can be a help to the economy of the project. 2. The proposed design method can be used as a way of retrofitting for the Sheet Piles that have lost their stability during the time or because of earthquakes. 4.3 Suggestions for Further Researches 1. The importance of soil behavior and different soil types in the structural behavior is highly suggested for further investigations. 2. This research is consummated on cantilevered Sheet Pile Wharf. So evaluation of Sheet Pile Wharf with tie rod is suggested for further investigations. 5. References 1. The Overseas Coastal Area Development Institute of Japan (OCDI) (2002), Technical Standards and Commentaries for Port and Harbor Facilities in Japan 2. PIANC (2001), Seismic Design Guidelines for Port Structures 3. Takahashi A (2003). Seismic performance evaluation of pile supported wharf by finite element analysis In: Proceedings of the 12th Asian regional conference on soil mechanics and geotechnical engineering. 1, 2003 pp Design of sheet pile walls (1996).Technical Engineering and Design Guides as Adapted from US Army Corps of Engineering, No