By Jie Zhang
Species in a natural forest thrive at multiple strata, with shrubs at one's foot & 100-meter-tall trees soaring into the sky, their interconnections promising an ecological symbiosis. Low-rise urban communities can co-exist with, and even support densification by analogy.
Urban villages prevalent in Chinese coastal cities epitomize the negotiation between an urgency in increasing land use intensity, and the long-term goal of even social upgrade and preservation of community fabric. Especially in Shenzhen, China’s first portal of modern economic reform, farmlands evolved in a period of 20 years into communities of 7-9 story walk-ups, built incrementally by local labor and housing the city’s sustained influx of migrant labor force. They boast a vibrant cultural identity and are situated as enclaves among newly-developed central business districts and residential high-rises. Under extreme pressure to meet housing needs, the city has been taking the conventional development process to build up by first flattening these villages, and has planned to transform Baishizhou, one of the largest and oldest urban villages, into a complex of multiple supertall buildings.
Inspired by the technique of grafting, UpGraft proposes to upgrade existing urban areas in place. By unlocking the latent real estate on roofs and in airspace, UpGraft proposes an alternative that selectively densifies a community using lightweight laminated veneer lumber (thereafter LVL) structures to allow symbiotic growth.
Prototyped in Baishizhou as a design system, these insertions and additions rise at 10-30 floors high, and feature added floor area with a small or no footprint. Lower levels are anchored to narrow plots or to existing buildings, serving as an infrastructural core. On the upper floor, micro residential units radiate around the building core, their sizes varying between 35 and 70 square meters. Skybridges connect towers at mid levels, establishing a new datum above the city. Given the sharing economy and a density of existing amenities in the community, only essential living needs are accommodated for an individual unit to keep them compact, affordable and efficient.
The rib cage-like structure for the towers is comprised of intersecting LVL panels, achieving a structural integrity through three-directional reinforcement. This method adapts the flat grid, or waffle grid structure common in slab or roof construction for the building skin, and in doing so, creates a structural lattice at the building periphery and thus liberating the floor plan.
The use of LVL panels is advantageous. Compared to concrete, which is the most prevalent structural material in China, LVL is just one small portion of the weight, and can be installed in less time. Vertical and horizontal ribs can be cut out of LVL panels en masse into custom shapes, liberating the form of the towers. The large size of LVL panels produces ribs that span floors and reduces the number of connections between elements. Finally, segments of a tower as an interlocked unit may be pre-fabricated, pre-assembled, and connected on site, continuing the tradition of incremental building native to urban villages towards the super-tall.