Wirtschaftliche Bemessung von Ankerplatten bei Litzenverpressankern

Economic assessment of anchor plates for grouting anchors

An economic anchor design includes the choice and the design of channel plates. If the anchor plates are directly placed on concrete (patched anchor plates) experiences in recent projects show that due to missing calculation models the design becomes uneconomic and leads to bulky anchor plates. This paper deals with the design of anchor plates directly placed on concrete. This includes diaphragm walls and bored pile walls, jet grouting underpinnings and gravity walls. Closely related to the design of steel anchor plates after DIN EN 1993-1 [1] is the analysis of concrete compressive strength after DIN EN 1992-1 [2]. In general, there are two possible ways for the design of the anchor plates. First, the common practice is to access the relevant general technical approvals (abZ) (see e. g. [3]), which, among others, include the anchor plate dimensions for appropriate minimum concrete strength classes. One part of the existing abZ refers to results of a separately conducted anchor plate design. Moreover, in the case of jet grouting due to the existing boundary conditions the received minimum compressive strength of the underpinning is lower as demanded in the abZ. In these cases it is necessary to perform a separate anchor plate design. Today, the design of anchor plates is done using classical static approaches or finite element simulations. Both approaches have significant weaknesses. Regarding the classical static approach the three-dimensional load carrying action is neglected whereas finite element simulations are rather complex and need extensive computing facilities. However, taking the "easy" way using classical static approaches in most cases results in to large anchor plate dimensions which often are too bulky for everyday construction business. This paper presents a simple static approach for the anchor plate design considering the three-dimensional load carrying mechanism of the anchor plates. This approach leads to a more economic design of the anchor plates resulting in much better manageable anchor plate dimensions.