A new modular building system for temporary structures consisting of reusable metal or plastic joints, bars, and plates.

In various social and economic sectors an increasing demand for temporary infrastructure emerges, such as pop-up co-working initiatives, festival pavilions, and exhibition stands. Modular and reusable building systems provide a solution to deal with this phenomenon in a sustainable way, so supporting the transition to a more circular economy. Modular structures start from a system of components that allows users to design a diversity of constructions. These structures are ideal for temporary applications if they are designed so that construction and dismantling go fast. In this work, the focus is on two types of modular building systems: (1) medium-scale systems, constructed by trained workers and, (2) small-scale systems, positioned in a STEM context, for children and their parents to build and experiment with. Both types of systems have opportunities for improvement, which are addressed in the thesis as two separate problems. 

Development of a small-scale modular building system

For small-scale temporary structures, few systems exist for human-scale structures (like Quadro) in a STEM context (like K’NEX). This gap is an opportunity to develop a new small-scale modular building system. In this thesis, a prototype for a new small-scale modular building system is developed. Bearing the intended users (children and their parents) in mind, the ease of use and the safety of the system are of great importance. First, a literature review of existing modular building systems is performed. Next, a set of practical, structural, and educational requirements is listed. In addition, in an iterative and incremental design process, and using mechanical tests to validate the loading capacity of the components, a final design for the system is found, consisting of a newly developed boltless diaphragm connection mechanism and its associated joint that allows for 18 bar connections. The kit of parts is manufactured, several structures are demonstrated, and a scenario for a STEM workshop is proposed. 

Optimization of a medium-scale modular building system

In this work, the existing medium-scale modular building system Vakwerk is chosen as a base. The system consists of standard scaffolding bars and a custom designed joint that allows the connection of up to 12 bars. A large share of the weight of the kit of parts of this building system is represented by the joints. Therefore, the focus should be on the reduction of redundant material, thus improving the structural efficiency and the ease of handling of the joints. Continuum topology optimization is a proven methodology to cope with suchlike problem. An optimization strategy is proposed that aims to minimize the weight of a joint, including constraints on the stresses in the joint. The principal scientific challenge imposed by the inclusion of stress constraints is twofold: (1) the analytical expression for the stresses becomes discontinuous if material is removed, which is especially problematic with respect to gradient-based continuum topology optimization, and (2) numerical solvers have difficulty handling problems with (that) many constraints. These problems can be alleviated by commonly used techniques such as constraint relaxation and constraint aggregation, but this results in highly over-conservative designs. To tackle this problem, three new strategies are proposed: (1) a continuation scheme on the P-norm exponent, used for aggregating the constraints, (2) a scaling operation to compensate any overestimation of the P-norm aggregation, and (3) the combination of both the continuation scheme and the scaling operation. The results show that up to 72% of the weight of the original Vakwerk joint can be saved using the proposed strategies. Finally, the optimized design is manufactured and demonstrated.