Abstract: Differences between virtual models and schedules with manufacture/construction reality deeply depend on modeling methods. In case of space frame modeling, models should not be only for visualization, architectural document but also be transferred to structural analysis software without remodeling… (that means BIM principle to be secured). Two approaches of using Adaptive families and Dynamo are suggested solutions.
Bim philosophy may lead to the complexity of modeling process and performance therefore, it is reasonable to mediate by looking for acceptable solution.
Hardware capability, performance and level of detail in construction site and/or factory should be considered in choosing modeling approach to meet management requirement.
-Space frame types: Flat, barrel vault, dome, free form. In fact, Flat and Barrel vaulted types are popular the most.
The objectives of modeling process:
(1) the equal length of members (bars);
(2) they can take the role of structural member (taking loads) in analysis modules
(3) their model is parametric and closest to real product.
While Revit has been a giant in BIM software market, Dynamo – a visual programming add-in for Revit, just appeared recently.
Modeling processes mentioned in this case use Revit 2015 and Dynamo 1.0.0.
The most of suggestion found using adaptive family for modeling the space frame unit and curtain wall grid technique. Massing by sweeping a profile along multiple segment path to make multiple bars has many issues that violate BIM principle:
-Revit model of bars differ from the real bars and
-Overestimating of material for bars
-Not enabling bar schedule
-Have to remodeling in structural analysis modules
In the course of Computational Logic at Revit Technology Conference (RTC), Håvard Vasshaug presented a brilliant solution of Dynamo using surface based method to generate the double grid for a free form space frame.
In fact, flat and barrel vaulted types (with double layer) have been implicated the most. This case shows modeling two types with two approaches: Adaptive family and Dynamo (Revit 2015)
Revit Adaptive based Space Frame
Barrel Vaulted surface based Dynamo
Flat type unit based Dynamo
Barrel Vaulted unit based Dynamo
Adaptive family approach
Fully parametric model
Nested and shared families can be easily scheduled
No need additional tool (such as Dynamo)
Visibility of bars can be controlled individually via shared families
Family integrated in the revit file
Adaptive Bar families are not structural members therefore they cannot sync with structural analysis modules (although they can be one way transferred using wire model of bars)
Deep levels of nested families can cause slow performance
Adaptive bar family
Use two adaptive points to control the endpoints of bar. The tube and heads can be formed directly in the family or nesting others into. In this case, to avoid too many levels of nested family (3), all of components of bar family are created within the family.
Sphere (node component) is another adaptive family ready to be nested. In fact, the node is chamfered and has some threaded holes for connections.
Adaptive family of brace unit
The adaptive bar family is nested in this brace unit family. The five adaptive points are to control the endpoints. Nodes of the grid to attach adaptive points need calculating to meet equal condition of bars.
In its turn, the brace unit family is also nested in the frame family. In order to make the braces and the other bars are equal, some calculations based on Pythagorean theorem and trigonometric functions to define parameters. Although all of bar could be equal, in fact, due to requirement of roof shape, supports or columns position… bars in one direction may be different from the rests.
Barrel Vaulted type
Panel-based and adaptive based families cannot be manipulated, scheduling their parameters. Based on the arc goes through bottom nodes and the number of bottom nodes on two directions of the barrel vault, the height of the frame unit can also be determined via Pythagorean equations and trigonometric functions.
Structural frame family: remove the default ref plans of setback to add two new ones labeled with Setback parameter
Similar with Vasshaug’s method using Nathan Miller’s Lunchbox Quad Grid by Face node to generate the grid. The following images are the captured workspace creating a barrel vaulted space frame using surface based method. Surface based Flat type (not included in data) can be made with a little modification of defining the height of the unit using to offset the bottom surface
Define the typical unit (pyramid) to meet the basic condition and array them along the two directions of the grid. Many of calculations from adaptive family approach could be reused with some a little modification to meet Dynamo language.
Use a line (in flat type) and an arc (in barrel vaulted type) as the basic curves.
Firstly, nodes of 'Curve.CoordinateSystemAtParameter' and 'Geometry.Transform' to array members (bars and nodes) along the basic curve. The next step is to array the set into the other direction using 'Geometry.Translate' nodes
Barrel Vaulted type
Citizen in Planning (Hanging Plans in HCMC - A fascinating insight into Citizen Rights - Binh Quoi Case study) - Planetary Urbanism Competition, ARCH+
Two-dimension model of Urban PlanningThe ultimate strategy in Vietnam is defined by the National Goals of Urban Development. After the National Goals of Urban Development approved by the Prime Minister, sector ministries and administrative levels develop and implement plans complied with the National Goals and follow the framework which can be depicted as a two-dimension model in the figure below.
The framework was legalized in Vietnam Law of Urban Planning 2009. In this model, which seems to be designed for centralizing power to the national government, each plan in system is driven by plans from the upper administrative level (top-down) and by more “strategic” sectors plans in the same administrative level (left-right). On the other hand, it manipulates plans in the lower administrative level and more “technical” sector plans.