How to structure of a Ph.D. sandwich thesis?
This is the structure that worked for me and number of my friends throughout western European universities: 

Title: A title that reflects your contributions/publications. 

Table of contents

ACKNOWLEDGEMENTS 

ABBREVIATIONS 

Abstract 

INTRODUCTION 

Note on Introduction: Most important of all is to highlight what you want to answer in your research. Also the problem/motivation should be discussed here. 

Paper1 ... PaperN

Note On Paper-Based Chapters: The order of them are very important. Order them based on the content not the year of the publication. 

Evaluation: In this chapter put both the discussion and results. Try to figure out the benefits and shortcomings of your research.

CONCLUSIONS and Future Work: conclude based on your contribution and highlight the future work. 

REFERENCES

Note: Not so many students take time on organizing their references' style. Most of them just copy/paste the Bibtex code and don't look if all their references obey the same style rules. 

ANNEXES