The structural calculation document of bridge is the important information set to be maintained because it contains core information which can be reused for the diagnosis of structural safety and the damage assessment during the lifetime of bridges. In general, most of the structural calculation documents are managed through the paper-based documents or the electronic files generated by software such as word processor, spreadsheet program, etc. Such management way, especially in development of a decision support system, has a limitation in reusing the structural calculation information. Therefore, in the digitalization of structural calculation documents, a scheme which assures the flexible use of the document in the heterogeneous computing environment should be established. In the recent studies, the extensible markup language (XML) is widely used for the interoperability of document information. For example, Zhu et al. (2001) proposed a framework for the construction process based on XML-based technology; Tserng & Lin (2003) developed XML schema for scheduling based on the aecXML framework; Zhilian et al. (2004) provided an in-formation exchange method in the construction project based on XML technology and they use it to develop a decision support system for the construction phase (Zhilian et al. 2005); and Lee et al. (2004) developed an XML-based framework for bridge design documents. In general, the document schema is used to operate the XML document and the data schema can be seen as a semantic model for the document. Therefore, as Song et al. (2002) pointed out, it is generally true that the standardization of the document data requires a large degree of agreement upon format, contents and responsibilities. However there are few researches that are reported in the literatures for the efficient standardization of the document model. This study provides a new formal standardization methodology of the structural calculation document for bridge maintenance and a standardized semantic model of the structural calculation document for general types of the steel bridges by using the developed methodology. Application modules capable of checking document data and storing them into a standardized database are also developed. The standardization process of the structural calculation document is composed of three stages. In the first stage, sample documents are collected, and specific document contents in the collected documents are indexed with templates defined in this study to make the document contents and their structures recognizable in the application program. In this study, the text file format is used as a neutral file format of the collected document contents because it can be exported easily from the most of the commercial programs. The second stage that deals with construction of temporary document schema can be divided into three steps. In the first step, the indexed document is read by the application program, and a document tree is made on the computer memory. Thereafter, the document tree which is a new collected document schema can be compared with the temporary document schema by using the schema matching techniques presented by Yi et al. (2005), and then the new content object is added to temporary document schema. This second part is repeated until all of the collected documents are compared. As a final stage, the common elements and unbounded elements are extracted by determining the occurrence of the temporary document elements, and the standardized document schema is exported in the XSD format. (Figure Presented) For a case study, the 41 kinds of structural calculation documents subjected to steel plate girder bridges and steel box girder bridges are collected, and all of the bridges are in the first and second classes determined by "Special Act on Safety Control for Infrastructure" in Korea. The standardized semantic model was composed of 5 major parts: design conditions, design of bridge deck, design of structural members, design of utilities, and usability check. Figure 1 illustrates web-based application examples of the standardized semantic model developed. The XML generator shown in Figure 1(a) is capable of translating the original document into XML document. After the translation is complete, the structural calculation document can be stored in the XML database and it can be retrieved on the web browser as shown in Figure 1(b). The Relay Module supports the integrated operation of the STEP-based bridge information (Lee & Jeong, in press) and the XML-based document information. Figure 1(c) shows an example of the integrated document viewer displaying the section information of a girder in segment 'NM1' of the Hannam bridge. The lower section of Figure 1(c) represents a result of data consistency check. Considering the fact that different users prepare the document information and the CAD information in general situations, this is a useful function to guarantee the data consistency during the long-term lifetime of bridges.