{"id":24664,"date":"2026-02-01T20:46:36","date_gmt":"2026-02-01T20:46:36","guid":{"rendered":"http:\/\/141.23.68.248\/wp\/?page_id=24664"},"modified":"2026-02-09T19:16:34","modified_gmt":"2026-02-09T19:16:34","slug":"parametricmodeling","status":"publish","type":"page","link":"http:\/\/141.23.68.248\/wp\/?page_id=24664","title":{"rendered":"Parametric Modeling"},"content":{"rendered":"\n

This project developed a parametric truss bridge model by Dynamo to study how key geometric choices influence the overall design (see Figure 1). The modelling process began by defining a central alignment for the bridge and generating two offset lines to represent the longitudinal boundaries of the truss. These lines were divided into evenly spaced points according to the selected panel number, which provided the basis for constructing the lower chord, upper chord, diagonals and vertical members. Each element was first represented as a line and was later converted into a simplified three dimensional member by sweeping an assigned cross section along its path. The shapes and areas of the structural members follow the specifications reported by Gogou (2012), which are listed in Table 1.<\/p>\n\n\n\n

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Figure 1:<\/strong> Parametric truss bridge model developed in Dynamo<\/p>\n\n\n\n

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Table1: <\/strong>Cross-Section Dimensions and Areas of Members<\/p>\n\n\n\n

Throughout this process, several adjustable parameters were implemented as sliders so that the form of the bridge could be changed at any moment. The most important parameters include the bridge length, the bridge width, the elevation of the deck, the number of panels and the truss height(see Table2). By linking these parameters to the geometry, the model allows rapid generation of alternative configurations and provides a clear view of how each parameter affects the bridge.<\/p>\n\n\n\n

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The design space of the parametric bridge model is defined by the adjustable ranges of the key geometric parameters. Short spans down to 10 m allow the exploration of compact truss forms, while the upper limit of 150 m represents the practical boundary for a single-span truss bridge before multi-span solutions become more efficient. The number of panels ranges from 3 to 12, which creates a wide variety of member lengths and internal force distributions. The truss height can vary from 3 m to 12 m, representing very shallow to relatively deep truss geometries, each with different implications for stiffness and clearance. Finally, the elevation and width parameters ensure that the deck position and the transverse spacing remain within typical values for road bridges.<\/p>\n\n\n\n

Selected Performance Criteria:<\/h2>\n\n\n\n

The evaluation of the parametric bridge model relies on three performance criteria. The first criterion is the total steel weight. This value is calculated by multiplying the length of each structural member with its corresponding cross sectional area and the density of steel. It provides an approximate measure of the material consumption of the design and therefore reflects both the economic cost and the environmental impact. A lower total steel weight indicates a more economical and sustainable solution.<\/p>\n\n\n\n

The second criterion concerns the structural layout efficiency of the truss, which is expressed by the ratio between the panel length and the truss height. When the ratio is small, the truss is relatively deep, the diagonals are steeper and the overall structural behaviour is more favourable. When the ratio becomes large, the truss becomes shallow and the diagonals are<\/p>\n\n\n\n

longer and flatter, which generally leads to reduced stiffness and higher deformation.<\/p>\n\n\n\n

The third criterion addresses the functional clearance above the deck, which is obtained by subtracting the deck depth from the truss height. This measure ensures that the design can accommodate the required vertical space for passing vehicles and equipment, and it also has implications for visual appearance and structural height.<\/p>\n\n\n\n

Design Alternatives and Comparison:<\/h2>\n\n\n\n

The comparison of the three design options is summarised in Table 3. In order to focus on the influence of the main structural parameters, the bridge width was fixed at 10 m and the bridge elevation at 5 m for all cases.<\/p>\n\n\n\n

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<\/p>\n\n\n\n

Option 1:<\/strong> represents a medium to long span truss bridge that is suitable for open sites or crossings where a single, uninterrupted span is preferred. Its span length of 120 m, together with twelve panels and a truss height of 12 m, gives the structure a balanced and stable form. However, if the span were to increase significantly beyond this length, a single span truss bridge might become less efficient, and a multi span arrangement or an alternative structural system would be more appropriate.<\/p>\n\n\n\n

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<\/p>\n\n\n\n

Option2 :<\/strong> Option 2 and Option 3 both represent short span solutions with a span of 40 m and a L_panel\/H of 1,0. Option 2 uses a small number of panels combined with a relatively deep truss. In this case, the stiffness is achieved mainly through the large truss height, which reduces deformation and keeps the diagonals at reasonable angles. The limited number of members also simplifies fabrication and assembly, and the total steel weight remains comparatively low.<\/p>\n\n\n\n

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Figure 3: <\/strong>Option2(L=40m, N=4, H=10m)<\/p>\n\n\n\n

<\/p>\n\n\n\n

Option3:<\/strong> Option 3, in contrast, uses a larger number of panels together with a shallower truss. The geometry relies on the closer spacing of members to obtain sufficient stiffness. The diagonals are shorter and their internal forces are generally more favourable, but the higher number of joints increases structural complexity and may lead to more demanding construction work. The total steel weight is slightly higher than in Option 2. For this reason, Option 3 is more suitable for local roads or secondary routes where clearance demands are lower.

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Figure 4:<\/strong> Option 3(L=40m, N=8, H=5m)<\/p>\n\n\n\n

Reference:<\/h2>\n\n\n\n

Gogou, E. (2012). Use of high strength steel grades for economical bridge design.<\/p>\n\n\n\n

Steel Truss Bridge<\/a> ><\/p>\n","protected":false},"excerpt":{"rendered":"

This project developed a parametric truss bridge model by Dynamo to study how key geometric choices influence the overall design (see Figure 1). The modelling process began by defining a central alignment for the bridgeContinue reading<\/a><\/p>\n","protected":false},"author":300,"featured_media":0,"parent":24657,"menu_order":0,"comment_status":"closed","ping_status":"closed","template":"","meta":{"footnotes":""},"class_list":["post-24664","page","type-page","status-publish","hentry"],"_links":{"self":[{"href":"http:\/\/141.23.68.248\/wp\/index.php?rest_route=\/wp\/v2\/pages\/24664","targetHints":{"allow":["GET"]}}],"collection":[{"href":"http:\/\/141.23.68.248\/wp\/index.php?rest_route=\/wp\/v2\/pages"}],"about":[{"href":"http:\/\/141.23.68.248\/wp\/index.php?rest_route=\/wp\/v2\/types\/page"}],"author":[{"embeddable":true,"href":"http:\/\/141.23.68.248\/wp\/index.php?rest_route=\/wp\/v2\/users\/300"}],"replies":[{"embeddable":true,"href":"http:\/\/141.23.68.248\/wp\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=24664"}],"version-history":[{"count":7,"href":"http:\/\/141.23.68.248\/wp\/index.php?rest_route=\/wp\/v2\/pages\/24664\/revisions"}],"predecessor-version":[{"id":28785,"href":"http:\/\/141.23.68.248\/wp\/index.php?rest_route=\/wp\/v2\/pages\/24664\/revisions\/28785"}],"up":[{"embeddable":true,"href":"http:\/\/141.23.68.248\/wp\/index.php?rest_route=\/wp\/v2\/pages\/24657"}],"wp:attachment":[{"href":"http:\/\/141.23.68.248\/wp\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=24664"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}