Performance of Prefabricated Cement Houses in Earthquakes

The performance of prefabricated cement houses in earthquakes depends on the degree of design standardization. Houses with standardized designs have strong seismic resistance, while those with non-standard designs pose significant risks.

Prefabricated cement houses with standardized designs exhibit excellent seismic performance:
Standardized prefabricated concrete structures utilize joint connection technologies, providing good ductility and energy dissipation capabilities. For example, they employ a dual-safety system of "full-frame shear walls + flexible connections", using C35 concrete for pouring, with built-in Φ12 - 18 threaded steel bars. Each column is reinforced with up to 8 steel bars, forming a load-bearing system akin to a "steel cage", with a lateral stiffness 6.8 times that of brick-and-concrete structures. Modules are welded together using E55 welding rods, with each connection point capable of withstanding 20 tons of tensile force. In simulated earthquake tests in Yunnan, the house experienced a maximum displacement of only 15 cm between modules during a rare 9-degree earthquake, with the overall structure remaining intact. The steel reinforcement mesh acts like a "building spring", absorbing energy through elastic deformation during earthquakes, withstanding up to 15 cm of deformation without breaking—7.5 times the safety threshold of 2 cm for brick-and-concrete structures. The prefabricated cement houses near the earthquake ruins in Ludian, Yunnan, remained stable after multiple aftershocks. In a case in Henan, cement houses in the same area only developed hairline cracks during a magnitude 5 earthquake, while more than twenty adjacent brick-and-concrete buildings collapsed, all confirming their seismic advantages.

Prefabricated cement houses with non-standard designs have weak seismic performance:
Early or non-standard prefabricated cement houses pose significant safety hazards. Hollow cement prefabricated panel houses have low seismic strength and were gradually phased out after the 1990s due to common ceiling cracks and inadequate seismic resistance, though they are still used in economically underdeveloped areas. These buildings use prefabricated panels placed directly on beams or load-bearing walls, with no connection between the panels and beams. In brick-and-concrete structures, except for structural columns and ring beams, other components are simply stacked. During earthquakes, buildings are prone to collapse layer by layer from the top, like building blocks. In the Wenchuan and Yushu earthquakes, a large number of such buildings collapsed, trapping people and making rescue difficult. Structures with interconnected steel bars further reduced survival chances.