I have developed a bridge model, form which I need to extract the strain value at certain locations. 

The model was created using shell elements (shown in the figure), I need to compare the strain values at the locations at which sensors are installed in real world. 

Initially, I extracted the strain data from the nodes which are closest to the sensor locations. But from the the nodal strain datasheet, I don't know why there are two sets of data at each node (shown in the figure).

However, I realised soon that strains are meant to be obtained from elements, but how to extract the strain values of the elements at which the sensor is located? It there a way to locate those elements knowing the coordinate of the nodes? (The sensor locations are shown in figure, represented by nodes)

Thanks.