In this paper, we describe an approach to analyze 2D truss/Frame/Beam structures under Flash-based environment. Stiffness Matrix Method (SMM) module was developed as part of ongoing projects on a broad topic "Students' Learning Improvements in Science, Technology, Engineering and Mathematics (STEM) Related Areas" at Old Dominion University (ODU), and funded by National Science Foundation (NSF). In this internet web based simulation, 2D Civil Engineering models for Truss, Frame and Beam structures can be created and analyzed with appropriately specified material properties, boundary conditions, and loads. The entire process for creating and analyzing structural models can be done online with user friendly web based tools. The module can be viewed at http://www.lions.odu.edu/~amoha006. Tutorials and demonstrated movies of the actual implementation of the models should make learners/users more comfortable. Theoretical description provides detail explanation of the theories behind the developed module. After the analysis is completed, the deflected shape of the structure and its' member stress intensities are also plotted. A self-assessment test module was developed which automatically grades the student's answers by comparing them with the computer generated solutions. The student's graded test score and the corresponding correct answers were automatically sent back to both the instructor and student through their email addresses. A survey was conducted between two classes in Spring '07 (without students being exposed to the developed SMM module) and Spring '08 (with SMM module) in Structural Analysis-I course at ODU. Preliminary results from the surveys have indicated that significant improvements in students' performance have been realized through the developed on-line SMM module. (Contains 2 tables and 9 figures.)