Ductility of Prefabricated Panel Houses
Prefabricated panel houses have poor ductility and weak seismic performance, primarily limited by construction techniques and design standards. Specific characteristics are as follows:
1. Weak seismic performance and insufficient integrity
Prefabricated panel houses are constructed using a splicing method, with a lack of steel bar connections between floor slabs and walls, relying solely on mortar jointing. This structure is prone to cracking and misalignment at the joints under seismic action, and in severe cases, the floor slabs may detach, leading to a loss of building integrity and significantly reducing escape time. For example, early prefabricated panel houses often experienced collapse of floor slabs and walls during earthquakes, directly threatening life safety.
2. Inherent process shortcomings, limited by materials and connection methods
The prefabricated panels themselves are hollow cement slabs, with only mortar used for jointing between panels. Compared to cast-in-place structures, their integrity, seismic resistance, and post-repair capabilities are significantly weaker. Cast-in-place structures form a continuous load-bearing system through integral pouring of reinforced concrete, whereas the joints in prefabricated panel structures easily become stress concentration points, prone to brittle failure under seismic or external forces. Additionally, the durability of mortar jointing is poor, and long-term use may lead to a further reduction in connection strength due to aging.
3. Limited renovation potential, requiring professional reinforcement
Although seismic capacity can be improved through reinforcement (such as adding steel bars to walls, reinforcing beams and columns, and applying carbon fiber sheets), professional assessment and targeted treatment are required. Ordinary renovations (such as painting walls or replacing pipes) cannot address the fundamental issue of insufficient structural ductility. For example, simply painting the wall surfaces or replacing pipelines cannot enhance the connection strength between floor slabs and walls, and structural failure may still occur during earthquakes, posing risks.
4. Differences in design standards, prominent historical legacy issues
The seismic fortification standards for early prefabricated panel houses were mostly set at 6 degrees, whereas current new residential buildings generally require 7-8 degrees. With the upgrading of seismic design codes, the issue of insufficient ductility in prefabricated panel houses has become more pronounced. For example, after the 2008 Wenchuan earthquake, a large number of prefabricated panel structures were damaged due to insufficient seismic capacity, prompting subsequent codes to impose higher requirements on structural integrity and ductility.
Summary: The ductility of prefabricated panel houses is limited by construction techniques, material properties, and design standards, necessitating professional reinforcement or renovation to enhance safety, rather than relying solely on the age of the building. For prefabricated panel houses with potential safety hazards, it is recommended to commission a professional institution for structural inspection and take targeted reinforcement measures based on the inspection results.
